Polymer Physicochemical Characterization of

Chapter 16

Polymer Physicochemical Characterization of Oligosaccharides Harry Levine and Louise Slade Fundamental Science Group, Nabisco Brands, Inc., P.O. Box 1944, East Hanover, NJ 07936-1944

' Thi s paper reviews the development and technological appli­ cation s of a polymer charac terization method, bas ed on low temperature differential s canning calorimetry (DSC), to analyze the structure-physicochemical property relation­ s hips of linear, branched, and cyclic oligos ac charides . The DSC method, bas ed on analog derivative thermograms , is u s ed to mea s u re Tg' , the characteri s tic s ubzero gla s s tran s ition temperatu re of a maximally freeze - concentrated aqueous s o­ lution . Solute-s pe cific Tg' value s have been mea s ured in order to evaluate the behavior of 9 1 commercial s ta r c h hy­ d roly s i s products (SHPs ) (i . e. dextrin s , maltodext rin s , corn s y rup s olid s , and corn s yrups , of dext ro s e equivalent (DE) 0 . 3 - 1 0 0 and polydis pers e molecular weight (MW» and 8 4 other polyhydroxy compound s (PHC s ) (i . e . s uga r s , polyhyd ric alcohols , and derivatized glyco s ide s , of monodi s pe r s e MW 6 2 - 1 1 5 3 ) (�). For the commer c ial SHP s , an inve r s e linear correlation exis t s between Tg' and DE. A plot of Tg' v s . number-average MW (Mn) demon s trated the clas s ical behavior of polydisper s e SHP s as a homologous family of amorphou s glucos e oligomers and polyme r s , and revealed an "entangle­ ment coupling" capability for polyme ric SHP s of Tg' � -8°C and DE $ 6 (i . e . Mn � 3000 and number-average degree of pol�nerization, DPn � 1 8 ) . In c ontrast to the higher Mn SHP s , the qua s i-homologous s e rie s of lower MW , monodis ­ per s e, monomeric and oligomeric PHC s , which included a ho­ mologous family of linear malto - oligo s a c charides of DP 1 - 7 and MW 1 8 0 - 1 1 53 , exhibited an invers e linear correlation between Tg' and l/MW, and thu s evidenced no capability for intermolec ula r entanglement in the maximally freeze - concen­ trated aqueou s glas s at Tg' . The s tructure - property rela­ tionShip between intermolecular entanglement (leading to three - dimen s ional network formation) and the functional behavior of polymeric SHP s as food ingredient s in applica­ tions involving gelation, encaps ulation, f rozen- s to rage s tabilization, thermomechanical s tabilization, or fac ilita-

0097-6l56/91/0458---{)219$11.50/O © 1991 American Chemical Society

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t i o n o f d ry i ng p r o c e s s e s has b e en d emon s t ra t e d a n d i s d i s ­ c us s e d . Th i s und e r l ying physico chemi c a l b a s i s f o r t h e em ­ pi r i c a l l y d emon s t ra t e d t echno l o gic a l uti lity o f low DE SHP s i n inh i b iting va r i ous " c o l lapse " phenomena , whic h a f f e c t t h e p r o c e s sing/ s t o r a g e s t ability o f many f o o d s , i s d e­ s c rib e d and exp l a in e d , a s is the c o n t ra s t ing r o l e t yp i c a l ly p l ay e d by sma l l s ug a r s and po lyo l s in p r omo ting t he s e us ua l ly d e t r iment a l phenomena .

I n t h e d e c a d e of the 198 0 s , the va lue o f a p o l yme r s ci e n c e a p p r o a c h t o t h e s tudy o f s t ru c t u r e - p ro p e r t y r e l a t i o n s h i p s i n f o o d ma t e ria l s, p ro d uc t s , and p ro c e s s e s ha s b e e n inc r e as i ng l y r e c og ni z e d by a g rowi� numb e r o f f o o d s c i ent i s t s ( 3 - 7 a n d r e f s . t h e r e i n ) . I n this r e s p e c t , f o o d s c i en c e ha s f o l l owe d the c omp e l l i ng l e a d o f the s yn t h e ti c p o l y ­ me r s fie l d . A s revi ewe d r e c e n t l y in d e t a i l e l s ewhe r e ( 3 - 7 ) , t h e eme rging r e s e a r c h dis c i pl i n e o f " f o o d p o lyme r s c i e nc e " emph a s i z e s t h, f undame nt a l and g e ne ric simi l a r i t i e s b e twe e n s ynthe tic p o l ym e r s and f o o d mo l e cu l e s , and p rovi d e s a new the o r e t i c a l and exp e r iment a l f rame wo r k f o r the s t udy of f o o d s y s t ems wh i ch a r e k i ne t i c a l l y c o n s t rain e d On a t h e o r e tic a l b a s i s o f e s t a b l i s h e d st ruc t ur e - p ro p e r t y r e l a t i o n­ s hip s f rom t h e fie l d o f s ynthe t i c po l yme r s ci e n c e (8-13), t hi s inno ­ va tive d i s cip l i ne ha s d eve l o p e d t o uni fy s t ru c t u r a l a s p e c t s o f f o o d s conc e p tua l i z e d a s k i n e t ica l l y - me t a s t a b l e , c omp l e t e ly amo rphou s or p a rt i a l l y c rys t a l l i ne , homo l o gous p o l yme r s y s t em s , wit h f un c t i ona l a s p e c t s , d e p endent up on mo b i l i t y and c o n c e p t ua l i z e d in t e rms o f " wa t e r dynami c s " and " g l a s s dynamic s " ( 3 - 7 ) . The s e uni f i e d c o n c e p t s have b e en u s e d t o exp l a i n and p r e d i c t the f un c tiona l p r o p e r t i e s o f f o o d ma t e r i a l s du ring p ro c e s sing and p roduc t s t o ra g e ( 1-7. 14-29 ) . Key e l ement s o f this theo r e ti c a l app r o a c h t o inv e s tig a tions o f f o o d s y s t ems , w i t h r e l evance t o mo i s tu r e mana gement a n d wa t e r r e l a tion­ s h i p s , i n c l ud e r e c o g n i tion o f : 1) the b ehav i o r o f f o o d s a n d f o o d ma t e ri a l s a s c l a s si c a l p o l yme r s y s t ems , and that t h e b ehavi o r i s gove rned by dynami c s r a t h e r t h a n ene r g e t i c s ; 2) t h e imp o r t a n c e o f t h e c h a r a c t e r i s tic t emp e ra t u r e Tg , a t wh i ch t h e g l a s s - rub b e r t rans i t ion o c curs , a s a phys i c o chemi c a l parame· t e r wh i ch can d e t e rmin e p ro c e s s i b i l i t y , p ro du c t p r o p e r t ie s , qua l i t y , s t a b i l i ty , and s a f e ty of f o o d s y s t ems ; 3) t h e c en t ra l ro l e o f wa t e r a s a ub iquitous p l a s tic i z e r o f n a t u r al and f a b r i c a t e d amo rphous f o o d i ng r e dient s and p ro duc t s ; 4) t h e e f f e c t o f wa t e r a s a p l as t i c i z e r on Tg and t h e r e s u l t i n g non-Ar rhenius , di f f u s i o n - l imited b ehav i o r o f amo rpho u s p o l ym e r ­ i c , o lig ome ric , and monome r i c f o o d ma t e ria l s in t h e rub b e ry liq· u i d s t a t e a t T > Tg ; t h e s i gnifi c a n c e o f non - e qui l i b r iwn g l a s s y s o l i d and rub b e ry 5) l iqui d s t a t e s ( a s eppo s e d t o e q ui l i b r i um t h e rmo dynami c p ha s e s ) i n a l l " r e a l wo r l d " f o o d p ro duc t s and p ro c e s s e s , and t h e i r e f­ f e c t s on t ime - d ep en de n t s t ructura l and me chan i c a l p ro p e r t i e s r e l a t e d t o qua l i ty and s t o ra g e s t a b i lity . I n p r evious re p o r t s and revi ews ( 1 - 7 . 1 4 - 2 9 and r e f s . t h e r e i n ) , we have d es c rib e d how the r e c ognit i on o f these key e l emen t s o f t h e f o o d p o l yme r s c i en c e app r o a c h a n d the i r re l evan c e t o t h e b ehavio r o f a b ro a d range o f d i f f erent types o f f o o d s ( e.g . i nt e rme d i a t e - mois t u re f o o d s ( IMF s) , l ow-mois t ur e f o o ds, fro z en f o o d s , s t a r ch-b a s e d f o o d s ,

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g e l a tin - , g l ut e n - , and o t h e r p ro t e i n - b a s e d f o o d s ) and c o r r e s p onding a q u e o u s mo d e l s y s t ems ha s i nc r e a s e d ma rke d l y during t hi s d e c a d e . We have i l l u s t ra t e d the p e r s p ect ive a f f o r d e d by using t hi s conc e p t ua l f ramewo rk and d emon s t ra t e d t h e t echno l o gic a l uti lity o f t h i s new a p ­ p ro ach t o und e r s tand and exp l a in comp l ex b ehavi o r, d e s i g n p roce s s e s , a n d p r e d ic t p r o duct qua lity, s a f e t y , and s t o ra g e s t a b i l i ty, b a s e d o n f undame nt a l s t ruc t u r e-p rop e r t y r e l a t i o n s h i p s o f f o o d s y s t ems v i e w e d a s homo l o g o u s f ami lie s ( i . e . monome r s , o l i g ome r s , and h i g h p o l ym e r s ) o f p a r t i a l l y c ry s t al line g l a s s y p o lyme r s y s t ems p l a s t ic i z e d by wa t e r . Re f e r r i ng t o t h e f o o d p o lyme r sc i e n c e app ro ach, J o hn B l an s h a r d ( Un i ­ v e r s i t y o f No t t ingham, p e r s ona l commun ica t i o n, 19 8 7 . ) ha s s t a t e d t ha t " i t i s no t o f t en t h a t a new c o n c e p t ca s t s f r e s h light acro s s a who l e a r e a o f r e s e a rch, but the r e i s l i t t l e doub t t ha t t h e r eco gn i t i o n o f t h e imp o r t an c e o f t h e t rans i tion f rom the g l a s s y t o t h e c ry s t a l l i n e o r rub b e ry s t a t e i n f o o dstuf f s , though we l l known i n s yn t h e t i c p o l y ­ m e r s, ha s o p en e d up new and p o t e n t i a l l y ve ry s i g n i f icant ways o f t hinking a b o ut f o o d p ro p e r t i e s and s t ab i l i t y. " I n a r ecent l e c t u r e o n his t o ri c a l d eve l o pment s in indus t r i a l p o lys accha r i d e s, J ame s B eMi l l e r ( Whi � t l e r C e nt e r f o r C a rbohyd ra t e Re s e a rch, Purdue Un ive r s i t y ) h a s e ch o e d B l an s ha rd' s wo r d s by r ema r k i ng t h a t a k e y p o i n t r e g a r ding t h e f u t u r e o f p o l y s accha r i d e r e s ea rch a n d t echno l o g y i s " t h e p o t e ntia l , a l r e ady p a r t ly r e a l i z e d, in app l y i ng i d e a s d eve l o p e d f o r s yn t h e ti c p o l yme r s t o po l ys a ccha r i d e s ; f o r examp l e , t h e impo r t ance o f t h e g l a s s y s t a t e i n many p o l y s accha r i d e app l ica t i o n s " ( 3 0 ) . I n t h i s a r t ic l e, w e i l l u s t ra t e t h e t h e o ry and p ra c ti c e o f f o o d p o l yme r s cienc e by h i gh l i ghting the d ev e l opment and t echno l o g ica l a p p l ica t i o n s o f a p o lyme r cha ra c t e r i z a t i on m e t ho d, b a s e d on l ow t em ­ p e r a t u r e D SC, t o ana lyz e t h e s t ruct u r e - phys icoch emica l p ro p e r t y r e l a ­ t i o n s h i p s o f l i n e a r , b ranched, and cyc l ic mono - , o l i g o - , and p o l ys a c ­ cha rid e s. The s e s t ud i e s have d emon s t ra t e d t h e maj o r o pp o r tuni t y o f ­ f e r e d b y t h i s f o o d p o lyme r s cience a p p r o ach t o exp a n d n o t o n l y o u r quantit a t ive know l e d g e b u t a l s o, o f b r o a d e r p ract ica l va l ue, o u r q ua l i t a t ive und e r s t and i ng o f the s t ruct u r e - f unc t i o n r e l a t i o n s hip s o f s uc h c a rb ohydra t e s i n a wi d e va r i e ty o f f o o d p ro duc t s a n d p r o c e s s e s . The o r e ti c a l Ba s i s o f the Cha r a c t e riz a t i o n M e t h o d - Tg ' : G l a s s Dynam ­ i c s; t h e St a t e D i a g ram as a Dynami c s Map Us e d to T race " C o l l a p s e " P h e nomena i n Fo o d s O u r m e t h o d o f cha rac t e riz ing t h e s t ruc t u r e - f unct i o n r e l a tion s hip s o f mono - , o l i g o-, a n d po l ys a c cha ri de s d e r i ve s f rom t h e f a c t tha t t h e i r f un c tiona l p rope r t i e s in f o o d s d e p end on mob i l i t y a n d can be und e r ­ s t o o d in t e rms o f t h e int e g r a t e d concep t s o f " wa t e r dynam i c s " and " g l a s s dynamic s " (1-7). Through t h i s i nt e g ra t i o n , t h e a p p r o p ria t e k i n e tic d e s c r i pt i o n o f t h e non-equi l i b r ium the rmome chani c a l b eh av i o r o f s uch f o o d ma t er i a l s ha s b e e n i l lustrated i n t h e c o n t ext o f a " dy ­ nami c s map " (11), a n examp l e o f wh i ch i s s hown i n F i gu r e 1 (Z). Thi s map wa s d e r iv e d f rom a g ene r i c s o l u t e - s olvent s t a t e d i a g ram (31,32), i n t u r n b a s e d o r i g i na l l y on a mo r e f ami l i a r equi l i b r i um p ha s e dia g ram of t emp e r a t u r e v s . compo sit i o n (23). The dynami c s map h a s b e e n u s e d t o d e s c r i b e mo b i l i t y t rans f o rma t i ons ( 23 ) i n wa t e r - c ompa t i b l e f o o d p o l yme r s ys t ems t h a t exi s t i n k i ne t i c a l l y - me t a s t a b l e g l a s s y a n d rub­ ' b e ry s t a t e s a lways s ubje c t t o cond i t i ona l l y b e ne f ic i a l o r d e t rime n t a l p l a s t ic i z a t i o n b y wa t e r (3-7). G l a s s dynam ics d e a l s with t h e t ime - and t empe r a t u r e - d ep e n d e nc e

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o f r e l a t i on s h i p s among c omp o s i t i on , s t ru c t u r e , the rmome c h a n i c a l p ro e r tie s , and f un c tiona l b e havi o r . As i t s name imp l i e s , g l a s s dynam i c f o cu s e s o n 1 ) t h e g l a s s" f o rming s o l i d s in an a queous f o o d s y s t em , 2 t h e Tg o f t h e r e s u l t ing aqueous g l a s s tha t c a n b e p ro du c e d b y c o o l i t o T < Tg , and 3 ) t h e e f f e c t o f t h e g l a s s t ra n s i t i o n a n d i t s Tg o n f o o d p ro c e s s i ng a n d p r o c e s s c o n t ro l , v i a t h e r e l a t i o n s h i p s b e tw e e n and t h e t emp e ra t u r e s o f indivi dua l p ro c e s s i ng s t ep s ( wh i ch may b e d e lib e r a t e l y c ho s en t o b e f i r s t a b o v e a n d t h en b e l o w Tg ) ( Q.l ) . T h c o n c e p t empha s i z e s the o p e ra t i ona l l y immo b i l e , s t a b l e , a n d un r e a c t i s i t u a t i o n ( a c t ua l ly one o f k i ne t i c m e t a s t ab i l i ty ) t h a t c a n o b t a i n during p r o duc t s t o ra g e ( o f a p r a c tic a l dura t i o n ) a t t emp e ra t u r e s b e l ow T g and moi s t u r e c o n t ent s b e low Wg ( t he amount o f wa t e r i n t h e g l a s s a t i t s Tg ) (�). I t ha s b e e n u s e d t o d e s c ri b e a uni f y i ng c o c e p t f o r int e rp r e ting " c o l l ap s e " phenomena , whi c h gove rn , e . g . , t h e t im e - d e p endent c a king o f amo rphous f o o d powd e r s during s t o ra g e (� C o l l a p s e phenomena in comp l e t e l y amo rphous o r p a r tia l l y c ry s t a l line f o o d s y s t em s ( 3 3 - 3 7 , 1 1 5 ) , examp l e s o f wh i ch a r e lis t e d in T a b l e I C .2.), a r e d i f f us i on- lim i t e d c o n s e quenc e s o f a ma t e r i a l - s p e ci f i c s t ru c t ur a l and/o r m e chani ca l re l axa tion p ro c e s s ( 1 ) . The mic ro s c o pi c a n ma c ro s c opic mani f e s t a t i o n s o f t he s e c o n s e quenc e s o c cu r i n r e a l time at a t emp e ra t u r e a b o u t 20 ° C a b ove t h a t o f an und e r l ying mo l e cu l a r s t a t e t ra n s f o rma t i o n ( 21 ) . Th i s t rans f o rma t i o n f rom kin e ti c a l l y - m e t s t a b l e amo rpho us s o l i d t o un s t a b l e amo rpho u s l i qu i d o c c u r s a t Tg (1 The c r i t i c al e f f e c t o f p l a s t i c i z a t i o n ( l e a d ing t o i n c r e a s e d f r e e vo ume (12) and mob i l i t y in the dynam i c a l l y c o n s t r a i n e d g l a s s ) by wa t e o n T g i s a k e y a s p e c t o f c o l l ap s e and i t s me chan i s m (1). A g e n e ra l phys ico chem i c a l me chani sm f o r c o l l a p s e has b e en d e ­ s c r i b e d ( 1 ) , b a s e d o n o c c u r r e n c e o f the ma t e r i a l - s p e c i f i c s t ruc t u r a t ra n s i ti o n a t Tg , f o l l owed by v i s c o u s f l ow i n t h e rub b e ry liqui d s t a t e ( 3 6 ) . The m e c hanism wa s d e rive d f rom Wi l l i ams - La nd e l - F e r ry ( WLF ) f r e e vo l ume t he o ry f o r ( s yn t he t i c ) amo rphous p o l ym e r s (12). ha s b e e n c onc l u d e d t h a t Tg i s i d ent i c a l t o t h e phenomeno l o g i c a l t raJ s i tion t emp e ra t ur e s ob s e rv e d f o r s t ru c t ura l c o l l ap s e ( T c ) and r e c ry: t a l l i z a tio n ( T r ) . The non - A r rh e n i u s k i n e tic s o f c o l l ap s e and/o r r e c ry s t a l l i z a tion in the high v i s c o s i ty (TJ) rub b e ry s t a t e a re gove rnel by t h e mo b i lity o f t h e wa t e r - p l a s tic i z e d po lym e r m a t rix . The s e ki­ n e t i c s d e p end on t h e magni tude o f aT T - Tg ( 1 ) , as d e f i n e d b y a t emp e ra t u r e-d ep endent exponent i a l r e l a tio n s hip d e riv e d f rom WLF t h e I ry . G l a s s dynam i c s ha s p roved a us e f u l c o n c e p t f o r e l ucida ting t h e p hy s i c o chem i c a l me chani sms o f s t ruc t u r a l/mechani c a l chang e s i nvo lvel in va rio u s me l t ing and ( r e ) c ry s t a l li z a tion p r o c e s s e s (1); Such p h e· nomena a r e o bse rve d in many p a r t i a l l y c ry s t a l l i ne f o o d p o l yme r s a n d p ro c e s sing/s t o ra g e s i t ua t i o n s (�). One p a r t i c u l a r l o c a t i o n among the c o ntinuum o f Tg va l u e s a l o n g t h e r e f e r e n c e g l a s s c u rve in F i g u r e 1 r e s u l t s f rom t h e b ehavio r o f wa t e r a s a c rys t a l l i z i ng p l a s t i c i z e r and c o r r e s p o n d s t o a n o p e ra tiol ally inv a r i ant p o int ( c a l l e d Tg' ) o n a s t a t e d i a g r am f o r any p a r tic1 l a r s o l u t e ( 1 .18 - 20 . 22,23.3 1 .3 8-4 2 ) . Tg ' r ep r e s en t s t h e s o l u t e - s p e· c i f i c s ub z e ro Tg o f the maxima l l y f re e z e - c o n c ent r a t e d , amo rphous s o: u t e/unf r o z e n wa t e r ( UFW) ma t rix s u r r o unding the i c e c ry s t a l s in a f ro z en s o lut i o n, As i l lus t ra t e d in the i d e a l i z e d s t a t e d i a g ram i n Fig u r e 1, t h e Tg ' point c o r r e s ponds t o, a n d i s d e t e rm i n e d b y , t h e point o f i nt e r s e c tion o f the k i n e t i ca l l y - d� t e rmine d g l a s s c u rv e f o r homo g en e o u s s o lut e - wa t e r mixt u r e s and t h e non - e q u i l i b r i um ext e n s i o n o f t h e e q u i l i b r i um l i q uidus c urve f o r the Tm o f i c e ( 1 , 1 8- 2 0 , 2 2. 2 3 ) , =

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:ab 1 e I. C o l l ap s e P ro c e s s e s Gove rned by Tg and D e p endent on P l a s t i c i­ z a t i on by Wa t e r �.

P ro c e s s ing and/o r s t o ra g e a t T < O ° C

1. I c e r e c rys t a l l i z a t i o n ( " g ra i n g rowth " ) 2 T r (*) 2. La c t o s e c rys t a l l i z a t i o n ( " s and ine s s " ) in da i ry p ro du c t s 2 Tr (*) 3 . E n z yma tic a c t i v i t y 2 Tg ' (*) 4 . St ruc t u r a l c o l l a p s e , s h r i nka g e , o r puf fing (o f amo rphous m a t r ix s ur r o und ing i c e c rys t a l s ) dur i ng f r e e z e - d ry i n g ( s ub l im a t i o n s t a g e ) � " me l t - b a c k " 2 Tc (*) 5 . S t ruc t ura l c o l l ap s e o r s h r i nka g e due t o l o s s o f e n t r a p p e d g a s e s during f ro z en s t o ra g e 2 Tg ' (*) 6 . So l u t e r e c rys t a l l i z a t i o n dur i ng f r e e z e - d rying ( s ub l ima t i o n s t a g e ) O!: T d (*) 7 . Lo s s o f e n c a p s ul a t e d vo l a t i l e s during f r e e z e - d ry i n g ( s ub l im a t i on sta g e ) 2 T c (*) 8 . Reduc e d s urviva l o f c ryop r e s e rved emb ryo s , due t o c e l l u l a r dama g e c a u s e d b y d i f f u s i o n o f i o n i c component s 2 Tg ' 9 . Reduc e d v i a b i l i t y o f c ryop ro t e c t e d , f ro z e n c o n c e n t r a t e d c he e s e ­ s t a r t e r c u l t u r e s 2 Tg ' lO. R e d uc e d v i ab i l i ty o f c ryop ro t e c t e d , v i t r i f i e d mamma l i a n o rg a n s due t o l e t h a l e f f e c t s o f i c e c rys t a l l i z a tion 2 Td l l . S t a l i ng due t o s t a r c h r e t r o g rada t i on via r e c ry s t a l l i z a t i o n in b r e a d s and o t h e r h i g h - mo i s t u r e , l e a n b a k e d p r o duc t s dur i ng f r e e z­ er s t o ra g e 2 Tg ' (*) 3.

P ro c e s s ing and/o r s t o ra g e a t T 20 ° C

1. C o h e siv e ne s s , s t i c k ing , a g glome ra tion , s int e r ing , l ump i ng , c a k i n g , a n d f l ow o f amo rphous powd e r s 2 T c (*) 2. P l a t i ng , c o a t i ng , s p r e a d i ng , and a d s o r b i ng o f , e . g . , c o l o r ing a g e n t s or o t h e r f ine p a r t i c l e s o n t h e amo rphou s s u rf a c e s of g ra n­ u l a r p a r t i c l e s 2 Tg 3. (Re ) c ry s t a 1 1 i z a t i o n i n amo rphous powd e r s 2 T c (*) 4 . Re c rys t a l l i z a t i o n due t o wa t e r vap o r a d s o rp t i o n d u r i n g s t o ra g e o f d ry - m i l l e d s ug a r s (i . e . g r i nd i ng � amo rphous p a r t i c l e s u r f a c e s ) 2 T g 5 . St ruc t u r a l c o l l ap s e i n f r e e z e-d r i e d p roduc t s (a f t e r s ub l ima t i o n s t a g e ) 2 T c (* ) 6 . Lo s s o f e n c a p s u l a t e d vo l a ti l e s in f r e e z e - d r i e d p ro du c t s (a f t e r s ub l ima t i on s t a g e ) 2T c (*) 7 . Ox i d a tion o f e n c a p s u l a ted l i p i d s in f r e e z e - d r i e d p r o duc t s (a f t e r s ub l ima t i o n s t a g e ) 2 T c (*) 8 . E n z yma t i c a c t ivity in amo rphous s o l i d s 2 Tg 9. Ma i l l a rd b rown i ng r e a c tions i n amo rphous powd e r s 2 Tg (*) lO. Suc ro s e i nve r s i o n i n a c i d - cont a ining amo rphous powd e r s 2 Tg ll. St i c k i ne s s i n s p ray - d rying and d rum-d rying 2 T s t i c ky p o i n t (*) l2. G r a i n i ng in bo i l e d swe e t s 2 Tg (*) l3. Sug a r b l o om i n c ho c o l a t e 2 Tg l4 . C o l o r up t a k e due t o dye d i f f us i o n t h rough we t f i b e r s 2 Tg l5 . G e l a tiniza tion o f na t ive g ranu l a r s t a r c h e s 2 Tg (*) Continued on next page

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Tab l e I.

Continued

1 6 . Sug a r - s nap c o o kie s p r e a d ing ( s o - c a l l e d " s ett i n g " ) during b aki� Tg (*) 1 7 . St r u c t u r a l c o l l ap s e dur i ng b a k i ng of high - ra t i o c a k e batt er f o l at e d wit h unch l o r i na t e d whe a t f l our o r w i t h r e c o n s titut e d f l o1 c on t a1n1ng waxy c o rn s t a r ch in p l a c e o f wheat sta r c h ( du e to I. o f d e v e l opment o f l e a ch e d - amy l o s e n e two r k Tg ) � Tg ' 1 8 . R e c rysta l li z a t i o n o f amo rphous s u g a r s i n· ( " dua l t e xtur e " ) c o o k: at the end of b a king vs. during sto r a g e � Tg 1 9. " Me l t ing" ( i . e . f l ow) of b a k e ry icing s ( mix e d s ug ar g l a s s e s ) ili to mo i stu r e up t a k e during s t o ra g e � Tg (,�) 20. S t a l i ng due t o s t a r c h retrog rada t i o n via r e c rys t a l liz ati o n in bre a d s and o t h e r high-mo i s ture , l e an b a k e d p roduc t s d uring sto: � Tg' (*)

(*)

Examp l e s exi s t in the f o o d s c i en c e and t e c hno l o gy lit era t ur e stabi liz a tion a g a i n s t co l l ap s e t h rough the us e o f l ow DE SHPl S e e ( 2 2 . 2 6) f o r p r evious ve r sions o f th i s T a b l e that list the r ef e r e nc e s .

TEMPERATURE T gSOLUTE

(----

W9J

WATER

Figure 1. Schematic state diagram of temperature vs. w% water for aqueous solution of a hypothetical, glass-forming, small carbohydn (representing a model frozen food system), illustrating how the critic locations of Tg' and Wg' divide the diagram into three distinguishal structure-property domains. (Reproduced with permission from reference Copyright 1991 Plenum.)

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l i s s o l u t e - s p e c if i c l o c a t i o n d e f i nes the c ompo s i t i on of the g l a s s la t c o n t a i n s the maximum p ra c t i c a l amount of p l a s t i c i z ing wa t e r :a l l e d Wg ' , exp r e s s e d a s g UFW/g s o l ut e o r we i ght % ( w% ) wa t e r , o r .t e rna t iv e l y d e s i gna t e d i n t e rms o f C g ' , exp r e s s e d a s w% s o l ut e ) · .....l) a n d r ep r e s en t s the t rans i t i o n f rom c o n c ent r a t e d f l u i d t o k i ne t ­ :a l l y - m e t a s t a b l e , dynami c a l l y c o n s t ra i n e d s o l i d tha t o c cu r s o n c o o l 19 t o T < Tg ' ( 2 5 ) . In t h i s homo g eneous , f re e z e - c o n c e n t r a t e d sol ­ : e-wa t e r g l a s s, t h e wa t e r r ep r e s ent e d by Wg ' i s no t "b o und " e n e rg e t ­ :a l ly but r a t h e r r e n d e r e d unf r e e z a b l e i n a p r a c t i c a l t ime f rame due I t h e immo b i l i t y impo s e d by the ext reme l y h i g h l o c a l v i s c o s i t y of lout 1 0 12 P a s at Tg' ( 1 - 7 , 1 8 - 20 . 22,23 . 3 8 - 42 ) . Ma r s h a n d B l an s h a r d �) have r e c ent l y do cumen t e d t h e t e chno l o g i c a l imp o r t a n c e of f r e e z e ­ Inc e n t r a t i o n and the p ra c t i c a l imp l i c a t i o n o f the d e s c r i p t i on of I t e r as a r e a d i ly c ry s t a l l i z a b l e p l a s t i c i z e r, cha ra c t e r i z e d by a .gh va l ue of Tm/Tg ra t i o 2 (23,44 ) . A t h eo r e t i c a l c a l cu l a t i o n f3 ) o f t h e Tg o f a typ i c a l l y d i l u t e ( i. e . 5 0 % ) whe a t s t a r ch g e l f e l l ! l l b e l o w the m e a s u r e d va l ue of a b o ut - 5 t o -7 ° C fo r T g ' ( 15 ) , b e ­ lus e the the o r e t i c a l c a l c ula t i on b a s e d o n f r e e vo l um e the o ry d i d n o t : c o un t fo r the fo rma t i o n o f i c e a n d f re e z e - c o n c e n t r a t i on tha t o c c u r s ! l ow a b out -3 ° C . R e c o gn i t i o n o f t h e p r a c t i c a l l imi t a t i o n o f wa t e r l a p l a s t i c i z e r o f wa t e r - c omp a t i b l e s o l ut e s , due t o t h e pha s e s ep a ­ l t i o n o f i c e , r e c o n c i l e d the d i ff e r e n c e b e tw e e n the o r e t i c a l a n d m e a ­ l r e d va l u e s o f Tg (23 . 4 3 ) . Mo reove r , the t h e o r e t i c a l c a l cu l a t i on s lpp o r t e d t h e me a s u r e d va lue o f - 27% wa t e r f o r Wg ' (12), t h e max imum ra c t i c a l wa t e r c o n t e n t of an aque ous whe a t s t a r ch g l a s s . The c a l cu ­ l t e d wa t e r cont e n t o f the whe a t s t a rc h g l a s s w i t h T g of a b o u t - 7 ° C s a b out 28% . A c r i t i c a l p o i nt imp l i c i t i n t h e i d e a l i z e d s t a t e d i a g ram i n F i g ­ r e 1 i s tha t the s t ru c t u r e - p ro p e rty r e l a t i o n s h i p s o f wa t e r - c omp a t i­ Ie f o o d p o lyme r s y s t ems a r e d i c t a t e d by a mo i s t u r e - t emp e ra tu r e - t im e Jp e rpo s i t i on ( 1.23 .3 6,45 ) . Vi s ua l izing F i g u r e 1 a s a dynam i c s map f mo b i l i t y , o n e s e e s t h a t the Tg curve r ep r e s ent s a b o un d a ry b e tw e e n on - e q u i l i b r i um g l a s s y s o l i d ( a t T < Tg ) a n d rubb e ry l iqui d ( a t T > g) phys i c a l s t a t e s ( 1 - 3 .42 ) . In these non - equ i l i b r i um s t a t e s , va r i ­ � s d iffus i o n - l imi t e d p ro c e s s e s ( e . g . c o l l ap s e phenomena i nvo l v i n g e c han i c a l a n d s t ru c t ura l r e l axa t i o n s ) e i th e r c a n ( a t T > Tg a n d W > g', t h e h i gh mo i s t ure p o r t i on o f the wa t e r dynam i c s d oma i n c o r r e ­ pond i ng to t h e upp e r - l eft p a r t of F i g u r e 1 , o r T > Tg and W < Wg ' , be l o w mo i s t u r e p o r t i o n o f the wa t e r dynam i c s doma i n c o r r e s p o nd i ng o t h e upp e r- r i gh t p a r t o f F i gure 1 ) o r c a nno t ( a t T < Tg , i n t h e oma i n of g l a s s dynami c s c o r r e s po n d i ng t o the b o t t om p a r t of F i g u r e ) o c cu r ove r r e a l i s t i c time s ( 1-3.4 2 ) . The WLF equa t i o n d e f i n e s t h e i ne t i cs o f mo l e c u l a r - l eve l r e l axa t i on p r o c e s s e s , wh i ch wi l l o c c u r i n r a c t i c a l t ime f r am e s o n l y i n t h e rub b e ry s t a t e a b ov e Tg , i n t e rm s of n expon e n t i a l, but non - A r rh e n i u s , func t i o n of AT a b ove t h i s b o un da ry ond i t i o n (L2l.). �

hy s i c o c hemi c a l Ba s i s o f the Exp e r iment a l DSC Cha r a c t e r i z a t i o n M e t h o d o r D e t e rm i n i n� T�' Va lue s o f C a r bohyd ra t e s i gu r e 2 (1 ) s hows typ i c a l l ow t emp e ra t u r e D S C the rmo g rams fo r 20 w% o l ut i o n s of a) g l uc o s e and b) a 1 0 DE ma l t o d ext r i n ( S t a l ey S t a r D r i 0) . I n e a c h , t h e h e a t f l ow c urv e b e g i n s a t t h e t o p ( endo t h e rm i c own ) , and t h e ana l o g d e r iva t ive t r a c e (endo the rmi c up and z e r o e d t o h e t emp e r a t u r e axi s ) a t t h e bottom . Fo r bo th the rmo g rams , i n s t ru -

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TEMPERATURE,

·C

TEMPERATURE,

·C

Figure 2. DuPont 990 DSC thermograms for 20 w% solutions of a) glucose and b) Star Dri 10 (10 DE) maltodextrin. In each, the heat flow CUrv4 begins at the top (endothermic down), and the analog derivative trac4 (endothermic up and zeroed to the temperature axis) at the bottom (Reproduced with permission from reference 1. Copyright 1986 Elsevier.)

16.

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ment a l amp l i f i c a t i o n and s en s i t iv i ty s e t t ing s we r e i d e n t i ca l, and s amp l e we i ght s c omp a rab l e . [ Fo r d e t a i ls o f the exp e r im e nt a l D S C m e t h o d o l o g y , s e e (�).l I t i s evi d e n t t h a t t h e d i re c t ana l o g d er iv­ a t i v e f e a t u r e of t h e D S C ( DuPont Mo d e l 99 0 ) g r e a t l y f a c i l i t a t e s d e ­ c o nvo lut i o n o f s equent i a l the rma l t rans i t i o n s , a s s i gnment o f pre c i s e t ra n s i t i o n t emp e r a t ure s ( t o ± 0 . 5°C f o r Tg ' va l u e s of dup l i c a t e s am ­ p l e s ) , a n d thus ove ra l l int e rp r e t a t i o n o f t h e rma l behav i o r , e s p e c i a l ­ l y f o r s u c h f ro z e n aqueous s olut i o n s exemp l i f i e d by F i gu r e 2 A . We c omme n t e d i n 1986 (1) on t h e s u rp r i s ing a b s e n c e of p r ev i o u s r e p o r t s o f t h e u s e o f d e r ivat ive t h e rmo g r ams , i n t h e many e a r l i e r D S C s t ud i e s o f s uc h s y s t em s w i t h wa t e r c on t ent > Wg ' ( s e e F ranks ( 3 8 ) f o r a n e x ­ t en s ive b i b l i o g raphy ) , to s o r t out the sma l l endo t h e rmi c and e xo t he r ­ m i c chang e s i n h e a t flow t h a t t yp i c a l l y o c cur b e l ow O ° C . Mo s t mo d e rn c omme r c i a l DSC i n s t rument s p rov i d e a d e r iva t ive f e a t u r e , but i t s u s e fo r i n c r e a s e d i n t e r p r e t a t ive c a p abi l i t y s t i l l app e a r s t o r ema i n muc h n e g l e c t e d i n t h e t h e rma l ana l y s i s o f foo d s i n g e n e r a l , and f roze n a qu e o u s f o o d s y s t em s i n p a r t i c u l a r ( 22.4 6 ) . . D e s p i t e t h e hand i c a p o f s u c h i n s t rumen t a l l imi t a t i on s i n t h e p a s t , t h e t h e o r e t i c a l ba s i s f o r the t h e rma l p ro p e r t i e s o f a q u e o u s s o l u t i on s a t sub z e ro t emp e ra t ure s ha s c ome t o b e i n cre a s i n g l y und e r ­ s t o o d ( 3 1 .3 2 . 3 8-4 0.47 - 4 9 ) . As s hown in F i gure 2A , a f t e r r a p i d c o o l ­ i n g ( a bout 5 0°C/m i n ) o f the g l uco s e s olut i o n f rom r o om t emp e ra tu r e t o < -8 0 ° C , s l ow h e a t i n g ( 5 ° C/m i n ) revea l s a m i no r T g a t -6l. 5 ° C , f o l ­ l ow e d by a n exo t h e rm i c d e v i t r i f i c a t i o n ( a c ry s t a l l i z a t i o n o f s om e of the p r ev i o u s l y UFW) a t Td -4 7 . 5 ° C , f o l l o w e d by a n o t h e r ( m a j o r ) Tg , name l y Tg ' , a t -43 ° C , and fina l ly the me l t i ng o f i c e , b e g i nn i n g a t T > Tg ' and end ing a t Tm . I n F i gure 2 B , the ma l t o d ex t r i n s o l u t i o n t h e rmog ram s hows o nly an obv i o u s Tg ' a t - 1 0 ° C , f o l l ow e d b y Tm . The s e a s s i gnment s o f c ha r a c t e r i s t i c t rans i t i o n s ( i . e. t h e s eq u en c e Tg < T d < Tg ' < Tm ) and t emp e ra t ure s have b e e n r e c o nc i l e d d e f i n i t iv e l y w i t h a c t ua l s t a t e d i a g rams p r evi ous l y r e p o r t e d fo r va r i o u s s o l u t e s , i n ­ It c l ud i ng smal l s ug a r s and wa t e r - s o lub l e p o l yme r s ( 1 8. 2 0.3 8.4 9 ) . has b e en d emon s t ra t e d ( 1 . 2 0 ) t h a t t h e t h e rm o g ram fo r t h e g l uc o s e so ­ l ut i o n i n F i gure 2A rep r e s ents a char a c t e r i s t i c examp l e , i f s omewha t t r i v i a l c a s e (11), of the unu s ual phenom enon o f mult i p l e va l u e s of T g i n g l a s s -f o rm i n g s y s t ems , wh i ch i s a s ub j e c t o f i n c r e a s i ng c ur r e n t i nt e r e s t i n the c ryo t e chno l o g y f i e l d ( 1 . 2 . 1 8 . 1 9. 2 0 . 2 2 . 5 0 - 5 3 ) . Due t o i n c omp l e t e p ha s e s ep a rat i o n ( 5 0 - 5 3 ) i n a n i n c omp l e t e ly f ro z en a qu e o u s s o l ut i o n , two d i s t i ngui s hab l e dynam i c a l l y - c o n s t ra i n e d g l a s s es , w i t h l o c a l doma i n s o f s uf f i c i ent d ime n s i o n ( i . e . > 1 0 0 A ( 2 » a n d c o o p e ra ­ t iv i t y t o a llow r e a dy det e c t i o n , may c o ex i s t ( 2 3 . 5 3 ) . One i s a "bul k" g l a s s w i t h the s am e s p a t i a l homo g e ne i t y and s o lut e c o n c ent ra t i o n a s t h e o r i g i na l d i l ut e s o lut i o n and a c o r r e s p o n d i ng l ow va lue o f T g . The o t he r , s u r r oun d i ng the i c e c rys t a l s , i s t h e f r e e z e - c o n c e n t r a t e d g l a s s w i t h a h i ghe r va l ue o f Tg , wh i ch i s T g ' ( 1 .2. 1 8 - 2 3 ) . The l owe r lim i t ing va lue of Tg fo r t h e d i lut e bulk g l a s s i s Tg o f p u r e amo r ­ phous s o l i d wa t e r i t s e l f ( about - 1 3 5°C ( 5 5 » , and t h e upp e r l im i t i n g va l u e o f Tg ' f o r t h e f r e e z e- c o n c e n t r a t e d g l a s s i s T m of p u r e c ry s t a l ­ l i ne wa t e r ( 20 ) . The o b s e rva t i on of s uc h a Tg + T g ' d o ub l e t d e p e n d s o n samp l e mo i s t u r e c ont ent , c o oling/h e a t ing h i s t o ry , a n d p r e ssure h i s t o ry ( 2 3 . 5 3 ) , and r ep r e s ent s an examp l e o f t h e d i f f i cu l t y t h a t c a n b e e n c o un t e r e d i n d e c o nvolut i ng the non - e q u i l i b r i um e f f e c t s o f s amp l e h i s t o ry ( 54, 1 1 9 ) , and the r e s u l t ing p o t e n t i a l f o r m i s i n t e rp r e t a t i o n tha t c a n a r i s e wh en exp e r iment s on f ro z e n aqueous s ys t em s a r e no t d e s i gned f r om a know l e dg e o f t h e o p e r a t ive refe r e n c e s t ate ( 5 0-5 2 ) . =

228

BIOTECHNOLOGY OF AMYLODEXTRIN OLIGOSACCH

The idealized state diagram shown in Figure 3 (20), modifiE from MacKenzie and Rasmussen ( 4 9 ) , exemplifies those previously ported and reveals the various distinctive cooling/heating path� can be followed by solutions of monomeric (glucose) vs. polymeri (maltodextrin) saccharide solutes during typical low temperaturE As demonstrated by the DSC thermograms in Figure < experiments. either general case, and regardless of initial cooling rate, re� ing from T < Tg' forces the system through a solute-specific glc As illustrated in the state diagram in E transition at Tg' ( 1 ) . 3 , the Tg'-Cg' point represents a "universal crossroads" on this in that all cooling/heating paths eventually lead to this point As shown by one of the idealized paths in Figure 3 , slow cooling stereotypical sugar solution from room temperature (point X) to temperature corresponding to point Y can follow the path XVSUWY, which passes through the Tg'-Cg' point, W. In the absence of und cooling (e.g. upon deliberate nucleation), freezing (ice formati begins at point V (on the equilibrium liquidus curve, at a subze temperature determined by the MW and concentration of the partic solute, via colligative freezing point depression) and ends at p W (on the non-equilibrium extension of the liquidus curve). Due vitrification of the Tg'-Cg' glass at point W, some of the water the original solution (i.e. an amount defined as Wg') is left un zen in the time frame of the experiment. This UFW is not "bound the solute nor "unfreezable" on thermodynamic grounds, but simpl experiences retarded mobility in the Tg'-Cg' glass. The extreme high local viscosity of this kinetically-metastable, dynamically strained glass prevents diffusion of a sufficient number of wate molecules to the surface of the ice lattice to allow measurement its growth in real time (1.38-42). As exemplified by the thermo for the maltodextrin solution in Figure 2B, rewarming from point point X can follow the reversible path YWUSVX, passing back thro the Tg'-Cg' point at W (20). In contrast to the slow-cooling path XVSUWY in Figure 3 , qu cooling can follow the direct path from point X to point Z, wher vitrification can occur at T Tg, the temperature corresponding point A, without any freezing of ice or consequent change in the However, unlike path XVSUWY, tial solution concentration ( 4 9 ) . XZ is not realistically reversible in the context of practical w ing rates (2Q). Upon slow, continuous rewarming from point Z to point X, the glass (of composition Cg-Wg rather than Cg'-Wg') so as the system passes through the Tg at point A , and then devitri at the Td at point D ( 4 9). Devitrification leads to disproporti, tion, which results in the freezing of pure ice (point E ) and reo trification via freeze-concentration of the non-ice matrix to Cg (point F) during warming ( 4 9 ) . Further warming above Td causes glass (of composition Cg'-Wg' rather than Cg Wg) to pass through Tg'-Cg' point at W (where ice melting begins), after which the Sl tion proceeds along the liquidus curve to point V (where ice mell ends at Tm), and then back to point X. The rewarming path ZADFWl (20) is exemplified by the thermogram for the glucose solution il Figure 2A. The third cooling path illustrated in Figure 3, XQSUWY, is 1 one most relevant to the practical cooling and warming rates inv( in commercial frozen food processes (20) Cooling of a solution point X can proceed beyond point V (on the liquidus curve) to poi =

-

0

16.

LEVINE & SLADE

Characterization of Oligosaccharides

229

Q, b e c a u s e t h e s y s t em c an und e r c o o l to s ome s i g n i f i c a n t ext e n t b e f o r e h e t e ro g e n e o u s nuc l e a t i o n o c c u r s a n d f r e e z ing b e g i n s ( 3 8) . Upon f r e e z ­ i ng a t p o i n t Q, d i s p ro p o r t i o na t i o n o c c u r s , r e s u l t ing i n t h e f o rma t i o n o f p u r e i c e ( p o i n t R) a n d f r e e z e- c o n c e n t ra t i on o f t h e s o l u t i o n t o po int S ( 3 8 ) . The t emp e r a t u r e a t po i n t S i s a b o v e t h a t a t p o i n t Q due t o t h e h e a t l i b e ra t e d by the f r e e z ing o f i c e ( 38) . The f r e e z e ­ c o n c ent r a t e d ma t r ix a t p o i n t S c o n c e n t ra t e s f u r t h e r t o p o i n t U , b e ­ c a u s e mo r e i c e f o rms a s t h e t empe r a t u r e o f the s y s t em r e l ax e s t o t h a t a t p o int U . Up on f u r t h e r c o o l ing b e yond p o i n t U , i c e f o rma t i o n a n d f r e e z e - c o n c e n t r a t i on c o n t i nue a s the s y s t em p r o c e e d s a l ong t h e l i q u i ­ d u s c u rv e t o p o i n t w. Vi t r i f i c a t i o n o f the Tg ' - C g ' g l a s s o c cu r s a t p o i n t W , and f u r t h e r c o o l ing o f t h i s g l a s s c a n c o n t i nue t o p o i n t Y w i t hout a dd i t i o na l i c e f o rma t i o n in r e al t ime . Rewa rmi ng o f t h e k i ­ n e t i c al l y - me t a s t a b l e gla s s f rom po int Y t o p o i n t X f o l l o w s t h e p a t h YWUSVX , wh i c h p a s s e s t h rough t h e Tg ' - C g ' p o i n t a t W . The a b ove d e ­ s c r i p t i on s o f t h e va r i ous c o o l ing/wa rming pat h s i l l u s t ra t e d i n F i gu r e 3 d emon s t ra t e t h e c r i t i c a l f a c t t h a t , r e g a rd l e s s o f c o o l i ng/wa rmi n g r at e s ( w i t h i n p ra c t i c a l l imi t s ) , eve ry a q u� ous s y s t em o f i ni t i a l c o n ­ c e n t ra t i on S C g ' , c o o l e d to T $ Tg ' , mus t p a s s t h r o ugh i t s own c ha r ­ a c t e r i s t i c and ope rati onal l y i nva r i ant Tg ' - C g ' p o i n t ( 2 0). I f, i n c omme r c i a l p r a c t i c e , a f o o d p r o d u c t i s no t c o o l e d t o T $ Tg' a f t e r f r e e z i n g , but r a t h e r i s ma i n t a i n ed w i t h i n the t emp e r a t u r e r a n g e b e ­ twe e n p o int s V and W , tha t s ys t em wou l d t ra c k b a c k and f o r th a l ong t h e l i qu i dus c u rv e as T f f l u c t ua t e s during s t o ra g e . The t e chno l o g i c a l s i gn i f i ca n c e o f Tg' t o t h e s t o rag e s t a b i l i ty o f f ro z en f o o d s y s t ems , imp li c i t i n the p r e c e d i ng d e s c r i p t i o n o f F i g ­ u r e 3 , w i l l b e d i s c us s e d l a t e r w i th r e g a rd t o C ryo s t ab i l i z a t i o n t e ch ­ S uf f i c e i t to s a y f o r now tha t Tg' ( o f t h e no l o gy ( 1 - 3 , 1 8 - 2 2) . f r e e z e - c o n c e n t r a t e d s o l u t i o n ) , ra the r than Tg ( o f the o r i g i na l s o l u ­ t i o n) , i s t h e only g l a s s t rans i t i o n t empe r a t u r e r e l evant t o f r e e z e r ­ s t o r a g e s t a b i l i t y a t a g iven f r e e z e r t emp e r a t ur e T f ( 2 0 ) , b e c a u s e a lmo s t a l l " f ro z e n " p r o duc t s con t a i n a t l e a s t s ome i c e . C o n s i s t en t w i t h t h e d e s c r ip t i o n o f t h e c o o l ing pa t h XVQSUWY , mo s t c omme r c i a l f o o d - f r e e z i n g p r o c e s s e s , r e g a r d l e s s o f c o o l ing r a t e , i nduc e i c e f o r ­ ma t i on b e g inning a t po i n t Q ( v i a h e t e r o g eneous nucle a t i on a f t e r s ome extent of und e r c o o l i ng) . S i n c e the t emp e r a t u r e a t p o i n t Q ( g e n e ra l ly i n t h e n e i gh b o rho o d o f -2 0°C ( 42» i s we l l a b ove t h a t a t p o i n t A, t h e l owe r T g , tha t o f the gla s s wi th t he o rig ina l s o l u t e ( s) c o n c e n t r a tion i n a t yp i ca l h i gh mo i s t u r e p ro d uc t , is neve r a t t aine d and t h e r e f o r e ha s n o p r a c ti c a l r e l evan c e ( 20 ) . On c e i c e· f o rma t i on o c cu r s i n a f ro ­ z e n p r o duc t , the p r e d omi nant s y s t em - s pe c i f i c Tg ' b e c ome s t h e o n e a n d o n l y g l a s s t ra n s i t i o n t emp e ra t u r e t h a t cont ro l s t h e p r o du c t's b ehav ­ i o r d u r i n g f r e e z e r s t o r a g e a t a ny Tf b e low Tm and e i t h e r a b ove o r b e l o w Tg ' ( 2 0 ) . The Ef f e c t o f Mo l e c u l a r We i ght on Tg F o r p u r e s yn t h e t i c p o l yme r s , i n the a b s e n c e o f d i luent , Tg i s known to va ry w i t h MW in a cha r a c t e r i s t i c and the o r e t i c a l l y p r e d i c t e d f a s h ­ ion , wh i ch ha s a s i gnif i c an t impa c t on r e s u l t i n g m e c ha n i c a l a n d rhe o ­ l o g i c a l p rop e r t i e s (�). Fo r a homo l o gous s e r i e s o f amo rphous l i n ­ e a r p o l yme r s , T g i n c r e a s e s w i t h i n c r e a s i ng Mn , due t o d e c r e a s i n g f r e e vo lume c o n t r i bu t e d b y cha i n ends (lQ), up t o a p l a t e a u l im i t f o r the r e g i o n o f " en t a ng l ement c o up l i ng" i n rub b e r - l i ke v i s c o e l a s ti c r a ndom n e two rks ( t yp i c a l l y a t M n 1 . 25 x 1 0 3 t o 1 0 5 d a l t on s ) ( 5 7 ) , t h e n l ev=

230

BIOTECHNOLOGY OF AMYLODEXTRIN OLIGOSACCHARII

Mn limit , there is a theoretical linear relationship between increa� ing Tg and decreasing inverse Mn (11), [For polymers with constant els off with further increases in Mn (10,12) ,

Below the entanglemer

values of Mn , Tg increases with increasing weight-average MW (Mw) , due to increasing local viscosity (2 3 ) , This contribution of loc al viscosity is report ed to be especially important when c omparing dif­ ferent MWs in the range of low MWs (lQ) , ] The differenc e in three­ dimensional morphology and resultant mechanical and rheological proI erties between a collection of non - entangling , low MW polymer chains and a network of entangling , high MW , randomly coiled polymer chains c an be imagined as analogous to the difference between masses of el­ bow macaroni and spaghetti (�), For synthetic polymers, the Mn at the boundary of the entanglement plateau often corresponds to about 6 0 0 backbone chain atoms (11), Since there are typically about 2 0 - 5 backbone chain atom� in each polymer segmental unit involved in the cooperative translational motions at Tg (58) , entangling high poly ­ mers are those with at least about 1 2 - 3 0 segmental units per c hain (�), Figure 4 (11) illustrates the chara c teristic dependenc e of Tg on Mn (expressed in terms of DP) for several homologous series of synthetic amorphous polymers, In this semi-log plot , the Tg values for eac h polymer reveal three distinguishable int ersec ting linear regions: III) a steeply rising region for non - ent angling small oligo mers; II) an intermediate region for non-entangling low polymers ; an I ) t he horizontal plateau region for entangling high polymers (59 ) , From extensive literature dat a for a variety of synthetic polymers , it has been concluded that this three - region behavior is a general feature of such Tg vs, log Mn plots , and demonstrated that the data in the non-entanglement regions II and III show the theoretically predic t ed linear relationship between Tg and inverse Mn (59 ) , Within a homologous food polymer family (e,g. from t he glucose monomer through maltose , maltotriose , and higher malto-oligosac char­ ides (e.g . maltodextrins) to the amylose and amylopectin high poly ­ mers of starch) , Tg' increases in a characteristic fashion with in­ This finding has been shown to be in creasing solute MW ( 1 .2 . 1 8) . full ac cord with the established variation of Tg with MW for homolo­ gous families of pure synthetic amorphous polymers (10,12,13 ) , de­ scribed above. The insights resulting from this finding have proved pivotal to the characterization of structure-function relationships in many different types of completely amorphous and partially c rys­ talline food polymer sys·tems (1 - 7 , 14 - 2 9) . The relationship between Tg' and solute MW has been established from DSC measurements of Tg' values for over 150 different food carbohydrates ( 1,2. 1 8. 1 9 ) . Eighty four of these were small carbohydrates (referred to as PHCs) of known, monodisperse MWs (i . e. Mw;Mn 1) . These PHCs represented a comprehensive but non - homologous series of mono - , di - , and small olio gosac charides and their derivatives, including many common sugars, polyols, and glycos ides , covering a MW range of 62 - 1 1 53 da1t ons. Ninety one others were SHPs, including monomeric , oligomeric, and high - polymeric sac charides, representing a homologous family of glu ­ cose polymers. These SHPs represented a spectrum of commerc ial prod­ u c t s (including modified starches , dextrins , maltodextrins , corn syr­ up solids , and corn syrups) , with polydisperse MWs (i. e. Mw ;Mn» 1), covering a very broad range of DE values (where DE 100/ (Mn/ 180. 2 ) ) from 0. 3 - 1 00 . [ For tabulated Tg' values for spe cifi c SHPs and PHCs , see ( 1 . 2. 1 8, 1 9 ) . ] =

=

16.

LEVINE & SlADE

Characterization of Oligosaccharides

T 00

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Figure 3. Schematic state diagram of temperature vs. weight percent solute for an aqueous solution of a hypothetical small carbohydrate (representing a model frozen food system), illustrating various cooling/heating paths and associated thermal transitions measurable by low temperature differential scanning calorimetry (e.g. as shown by the thermo grams in Figure 2). See the text for explanation of symbols. (Reproduced with permission from reference 20. Copyright 1989 Gordon & Breach.) 440

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Figure 4. Plot of Tg as a function of log DP (degree of polymerization) [a measure of Mn], for poly(alpha-methyl-styrene) (open circles); poly(methylmethacrylate) (open triangles); poly(vinyl chloride) (solid circles); isotactic polypropylene (solid triangles); atactic polypropylene (circles, top half solid); and poly(dimethylsiloxane) (circles, bottom half solid). (Reproduced with permission from reference 13. Copyright 1986 Wiley-Interscience.)

232

BIOTECHNOLOGY OF AMYLODEXTRIN OLIGOSACCHARID

For the SHPs, a homologous series of glucose oligomers and pol) mers , Tg' values ran�e from -43 °C for glucose (the monomer itself , c DE 100) to -4°C for a 0 . 5 DE maltodextrin. A plot of Tg' vs . DE (shown in Figure 5 (1» revealed a linear correlation between in­ creasing Tg' and decreasing DE (r -0 . 98) for all SHPs with manufac turer - specified DE values (1) . Since DE is inversely proportional t DPn and Mn for SHPs (60) , these results demonstrated that Tg' in­ creases with increasing solute Mn (from Mn 1 8 0 for glucose to 3 6 00 Such a linear correlation between Tg for 0 . 5 DE maltodextrin) (1). and 1jMn is the general rule for any homologous family of pure , glass - forming polymers (11). The equation of the regression line is DE -2 . 2 (Tg' , °C) - 12.8 , and the plot of Tg' vs . DE in Figure 5 ha proved useful as a calibration curve for interpolating DE values of new or "unknown" SHPs (2.). Results for polymeric SHPs have demonstrated that Tg' depends rigorously on linear , weight - average DP (DPw) for such highly poly­ disperse solutes , so that linear polymer chains (e . g . amylose) g i ve rise to a higher Tg' than branched chains (e.g: amylopectin , with mUltiple chain ends) of equal MW (�). Due to the variable polydis persity and solids composition of commercial SHPs (60,6 1) , the range of Tg' values for SHPs of the same specified DE can be quite broad . This behavior was shown by several pairs of SHPs (�). For each pair, of the same DE and manufacturer, the hydrolysate from waxy starch (all amylopectin) had a lower Tg' than the corresponding one from normal starch (containing amylose) . This behavior was also ex­ emplified by the Tg' data for thirteen 10 DE maltodextrins (�), fo whi ch Tg' ranged from -7 . 5 °C for a normal starch product to - 1 5 .SoC for a product derived from waxy starch , a ATg' of 8°C . Such a ATg' is greater than that between maltose (DP 2 ) and maltotriose (DP 3 ) (la). Further eviden ce was gleaned from Tg' data for selected glu­ cose oligomers (2). Comparisons of the significant Tg' differences among maltose ( 1 �4 - linked dimer) , gentiobiose ( 1�6-linked) , and iso­ maltose ( 1�6 - linked) , and among maltotriose ( 1�4 - linked trimer) , pan ose (l�4 , 1�6 - linked) , and isomaltotriose (h6, 1�6-linked) , have suggested that 1�4 - linked (linear amylose - like) glucose oligomers manifest greater "effective" linear chain lengths in solution (and , consequently , larger hydrodynamic volumes) than oligomers of the sam MW which contain 1�6 (branched amylopectin - like) links (26) . These results have also been used to illustrate the sensitivity of the Tg' parameter to molecular configuration , in terms of linear chain length , as influenced by the nature of the glycosidic linkages in various non-homologous saccharide oligomers (not limited to glucose units) and the resultant effect on solution conformation ( 12 ) . Fur­ ther evidence was seen in the Tg' values for other PHCs , where , for sugars of equal MW (e. g . 164) , ATg' is as large as 10°C , a spread even larger than for the thirteen 10 DE maltodextrins (la). Another interesting comparison was that between Tg' values for the linear an cyclic a- ( 1�4) -linked glucose hexamers , maltohexaose (- 14 . S0C) and a cyclodextrin (-9°C) . In this case , the higher Tg' of the cyclic oli gomer led to a suggestion (1) that the ring of a - cyc1odextrin appar­ ently has a much larger hydrodynamic volume (due to its relative ri­ gidity) than does the linear chain of maltohexaose , which is rela­ tively flexible and apparently can assume a more compact conformatio in aqueous solution . The abov£ comparisons have been discussed in the past to emphasize the subtleties of structure - property analyses =

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LEVINE & SlADE

Characterization of Oligosaccharides

233

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HI'1

234

BIOTECHNOWGY OF AMYLODEXTRIN OLIGOSACCHARIDE

of SHPs and PHCs by our DSC characterization method (21). The un­ avoidable conclusion , concerning the choice of a suitable carbohy­ drate ingredient for a specific product application , is that one SHP (or PHC) is not necessarily interchangeable with another of the same nominal DE (or MW) . Characterization of fundamental structure - prop­ erty relationships , in terms of Tg/ , has been strongly advised before selection of such ingredients for fabricated foods (�). The Tg' results for the commercial SHPs demonstrated exactly the same Tg vs . Mn behavior as described earlier for synthetic amorphous polymers. Tg' values for this series of SHPs (of polydisperse MWs in the range from 1 8 0 for glucose to about 60 0 0 0 for a 3 60 - DP polymer) thus demonstrated their classical behavior as a homologous family of amorphous glucose oligomers and polymers (�). The plot of Tg' vs . solute Mn in Figure 6 (1) clearly exhibits the same three - region be­ havior as shown in Figure 4 : I) the plateau region indicative of the capability for entanglement coupling by high polymeric SHPs of DE � 6 and Tg' � -8°C; II) the intermediate region of non - entangling , low polymeric SHPs of 6 < DE < 2 0; and III) the steeply rising region of The plot of Tg' non - entangling , small SHP oligomers of DE > 2 0 (2). vs . lIMn in the inset of Figure 6, with a linear correlation coeffi­ cient r 0 . 9 8 , demonstrates the theoretically predicted linear re­ lationship for all the SHPs in regions II and III, with DE values > 6. The plateau region evident in Figure 6 identified a lower limit of Mn 3 0 0 0 (DPn 1 8) for entanglement leading to viscoelastic net­ work formation (8.62) by such polymeric SHPs in the freeze - concen­ trated glass formed at Tg' and Cg'. This Mn is within the typical range of 1 2 5 0-19 0 0 0 for minimum entanglement MWs of many pure synthe­ tic amorphous linear high polymers (5 7 ) . The corresponding DPn of about 18 is within the range of 1 2 -3 0 segmental units in an entan­ gling high polymer chain, thus suggesting that the glucose repeat in the glucan chain (with a total of 2 3 atoms/hexose ring) may represent the mobile backbone unit invqlved in cooperative solute motions at Tg' (2) . The entanglement capability has been suggested to correlate well with various functional attributes (see the labels on the pla­ teau region in Figure 6) of low DE SHP& , including a predicted (1) and subsequently demonstrated (Z) ability to form thermoreversible , partially crystalline gels from aqueous solution (63 - 7 2.114). It has been suggested that SHP gelation occurs by a mechanism involving crystallization - pIus-entanglement in concentrated solutions under­ cooled to T < Tm, as descI"ibed elsewhere 0.). In contrast to the commercial SHPs , the series of quasi - homolo­ gous , monodisperse PHCs, including a homologous set of malto - oligo­ saccharides from glucose up to DP 7, was found to manifest Tg' values which fall below the Tg' limit defined by SHPs for entanglement and the onset of viscoelastic rheological properties and to be incapable of gelling from solution (�). The plot of Tg' vs . MW for all the PHCs in Figure 7 (Z), drawn conventionally as a smooth curve through all the points (1£), can easily be visualized to represent two inter­ secting linear regions (III for MW < 3 0 0 and II for 3 0 0 < MW < 1 2 0 0 ) (2). From the fair linearity of the Tg' vs. I/MW plot for all the data in the inset of Figure 7 , it was concluded that these diverse low MW sugars, polyols, and glycosides show no evidence of entangle­ ment in the freeze-concentrated glass at Tg' . The corresponding re­ sults for glucose and malto-oligosaccharides of DP 2 - 7 (shown in Fig­ ure 8 (1» demonstrated a better linear correlation , with r -0 . 9 9 =

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Figure 6. Variation of a glass transition temperature, Tg', for maximally frozen 20 w% solutions against Mn (expressed as a function of DE) for the commercial SHPs in Figure 5. DE values are indicated by numbers marked above the x-axis. Areas of specific functional attributes, corresponding to three regions of the diagram, are labeled. [Inset: plot of Tg' vs. lIMn (X 10 000) for SHPs with Mn values below entanglement limit, illustrating the theoretically predicted linear dependence.] (Reproduced with permission from ref. 1. Copyright 1986 Elsevier.)

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238

BIOTECHNOLOGY OF AMYLODEXTRIN OLIGOSACCHARIDES

for a plot of Tg ' vs . l /MW, s hown in the in s et of F igure 8 . Thi s linear dependence ( � ) of the Tg' res ults for the malto - ol i go s accha r ­ ide s i n a q ueous s o lution exemplif ied the theoreti cal glas s - forming behavi or (i . e . diluent - free Tg vs . l /MW) characteris t i c of a homolo ­ gous fam i ly of non-entangl i ng , linear , mono di s per s e oligomers (� 11 ) . For all the PHC s , none larger than a heptamer of MW 1 153 , the mai n plots in Figures 7 and 8 show that region I , repres enting the entanglement plateau where Tg remai n s con s tant with increa s i ng MW , has not been rea ched , in accord w i t h the MW (and corre s pondi ng DP) range cited above a s the lower limit f or polymer entanglement. S acchar i de Polymer s : Entangleme nt and Network Format ion - Network Tg

There is a profound technological importance of MW s above the entan ­ glement MW limit, as illus trated earl ier for commercial SHPs (a s a model for other homologous families of amorphous s accharide oligomers and p o l yme r s ) by t h e s tru c tur e func t ion relation s hips def i ned by the entanglement plateau in Figure 6 (� ) . Ferry ( lQ ) has des cribed the generic behavior obs erved for a 1 1 polymer s y s tems with res pect to the relation s hips between linear DP of the backbone chain , polymer con ­ centrat i on , and v i s cos ity . MW i s a re l ative mea s ure of linear DP of the primary chain , when the polymer has a un i f orm s t ructure along its entire length . At any given concentrat i on, there i s a minimum DP required for entanglement and network format i o n . For very dilute s o l ution s ( s uch that the s olution vis co s ity , meas ured as a relative flow rate , is s imilar to that of the s olvent alone) , high MW polymer s are nece s s ary t o form gels or networks (characterized by very high macros copic vi s co s ity , meas ured a s a relati ve firmne s s ) . For exam­ ple , 1 . 5 w% gelatin s olution s in water can form firm gel net works (wh ich exhibit res i s tance to dehydrat ion , due to mechan i ca i res i s t­ ance to s hrinkage (1 ) ) , through entanglement followed by cry s talli­ zation of j unction zones , if the li near DP i s � 1 000 (MW � 1 05 ) (7 3 ) . Similarly , 1 . 5 w% amylo s e s olution s in water can f o rm firm gel net­ works i f the linear DP is about 3 000 (Mw 5 x 1 05 ) ( 7 0 . 7 1 ) . At in ­ termed iate chain lengths greater concentration s of chain s are re­ quired f o r e n t ang l ement and ne two rk f o rma t i o n . I n t he cas e of SHPs ,. s uch as the low DE malto dextrin s p a t en t e d as partially cry s talline , fat - mimetic gels (6 3 . 6 4 . 6 9 ) , concentrations mu st be increa s ed to at lea s t about 20 - 25 w% in water (i . e . typical of Cg ' of the freeze - con­ centrated gla s s at Tg') as linear DP is decrea s ed to approach 18 glu ­ cos e un i t s (MW 3 000 ) (� ) . In c o ntra s t , ol i gomer s of hyd rolyzed gelatin (peptones ) or hydrolyzed s tarch (corn s y rup s ol i d s or h igher DE maltodextrin s with MW � 3 000 ) are incapable of gel network forma ­ t i on via entanglement at any conc e ntration (2 . 3 . 24 ) . However , recry s ­ tallization of s u ch oligomers can o c c ur due to concentrat i on above the s atu rat i on l i m i t or to a change of s olvent . For carbohydrate polymers ba s ed on pri mary cha ins of a- 1 , 4 glucan s , the cri t i cal DP requ i red for ne two rk f o rma t i o n v i a ent ang l ement i s. � 1 8 ( 1 ) . Network fo rma tion , espec i ally in the absence of cry s ta l l i zation , depends on the ab i lity of flexible chain s to entangle ( lQ ) . [ The contribut ion of crys tall ization to network formation and gelat i on , d e s c rib e d el s ewhere (3 - 7 ) , will be dis c u s s ed below i n the s pecif i c con t ext of s a c cha rid e p o l ym e rs , w i t h regard t o the ques tion - when i s retrogradat ion s ynonymous with rec rys tallization and w i th gelat i on ? ] O ne c o nve n i ent diagnos tic test f o r entanglement relies on the fact , -

�

,

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p r evious l y i l lus t ra t e d in F i gu r e s 4 and 6 , t ha t the Tg va l ue s o f a homo l o g o u s f ami ly o f po lyme r s i n c r e a s e w i t h i n c r e a s ing l i ne a r DP up t o the cha i n l eng t h s uf f i c i ent t o a l low entang l ement . Ent ang l ement ne two rks c o n s i s t o f int e rno d e cha i n s and ne two rk j unc t i o n z o n e s ( no d e s ) t h a t a r e t ra n s i ent t o p o l o g i c a l c o n s t ra i nt s t o c ha i n mo t i o n ( 5 7 . 7 4 ) . The p ro b a b i l i ty o f f o rma t i on o f ( non - c rys t a l l i ne ) j un c t i o n s d e p en d s o n cha i n l en g t h a n d c o n c ent ra t i on . T h e g r e a t e r t h e numb e r o f j un c t i on s , the s ho r t e r the i nt e r - no d e cha i n l eng t h ( f o r a f ix e d p a r ­ ent cha i n l en g t h ) . Thus , t h e r e i s a l imi t i ng l en g t h f o r a ny cha i n tha t exh i b i t s t rans l a t i o na l f r e e d om , a n d a l im i t ing mo l e cu l a r T g f o r tha t DP ( 1 ) . A s e c ond imp o r t a n t d i a gno s t i c t e s t f o r entang l ement ( Z ) i s i l ­ lus t ra t e d i n F i gure 9 ( lQ ) , a l o g - l o g p l o t o f vi s c o s i t y v s . MW f o r a s e r i e s o f s ynth e t i c po l yme r s . F o r und i lut e d po l yme r s o r f o r p o l ym e r s o lut i ons s t ud i e d a t con s t ant t o t a l c o n c ent r a t i o n , a c r i t i c a l cha i n l en g t h c a n b e d emons t ra t e d , above o r b e l ow wh i ch t h e d e p ende n c e o f v i s c o s i ty o n MW chang e s d rama t i c a l ly (lQ) . Above t h e c r i t i c a l cha i n l en g t h , e n t ang l ement r e s u l t s i n a d ra s t i c s en s i t iv i ty o f v i s co s i ty t o In the a b s e n c e o f entang l ement , cha i n s s ho r t e r than cha i n l e n g t h . t h e c r i t i c a l l e ngth s how s o lut i o n b ehav i o r with r e l a t ive i n s e n s i t iv i ­ ty o f v i s c o s i t y t o cha i n l eng t h . The t o p o l o g i c a l c o n s t ra i n t s o f t h e ( non - c ry s t a l l i ne ) entang l ement ne two rk a r e n o t due t o a ny p a r t i cu l a r chemi c a l i nt e r a c t i o n s ( s uch a s hyd r o g e n bonds o r d i p o l a r o r cha r g e i nt e r a c t i o n s ) , no r t o any p a r t i cu l a r s t ru c t u r a l f e a t ur e s ( 2 ) . A s d emon s t ra t e d i n F i gure 9 , ent ang l ement i s a g ene r i c b ehav i o r o f p o l y ­ me r s o f s uf f i c i ent cha i n l en g t h and c a n b e s e e n e q ua l l y i n p o l y ­ ( e t hy l en e g l y c o l ) a n d in non - p o l a r , s t ru c t u r a l ly f e a t u r e l e s s p o l yme r s s uc h a s p o l y ( i s o - bu t y l e ne ) . The imp o r t ant l e s s o n t o b e l e a rn e d f rom F i gure 9 ha s been d e s c r i b e d as f o l lows (Z) . The e n t ang l ement MW l im ­ i t , c o i n c i d ing wi th t h e c r i t i c a l l i n e a r D P r e q u i r e d f o r i n t e rmo l e cu ­ l a r ne two rk f o rma t i o n , c o r r e s p onds t o the p o i nt a t wh i ch t h e s l o p e chang e s a b rup t l y . I n the r e g i o n o f MW above the c r i t i c a l DP , t h e In th i s r e g i on , cut t ing s l o p e o f l o g v i s c o s i t y vs . l o g MW i s 3 4 mo l e c u l e s ( e . g . SHP s ) o f DP 3 0 0 i n ha l f , t o o b t a in t h e s ame t o t a l c o n c ent r a t i o n o f mo l e c u l e s w i t h DP 1 5 0 , wo u l d r e s u l t i n a 1 0 - f o l d r e d uc t i o n i n vi s c o s i t y . I n cont ra s t , i n the a b s en c e o f entang l ement , t h e s l o p e o f l o g v i s c o s i t y vs . l o g MW in the r e g i o n b e l ow t h e c r i t i ­ c a l D P i s 1 . I n th i s r e g i o n , cut t i ng mo l e cu l e s o f D P � 1 8 i n ha l f woul d r e s u l t i n o n l y a 2 - f o l d reduc t i o n i n v i s c o s i ty . I t ha s b e e n p o i n t e d out ( 11 ) that the l ow va l u e s o f l o c a l v i s ­ c o s i t y t yp i c a l l y f o und i n g l a s s - f o rming po lyme r s y s t ems a t T Tg + 1 0 0 ° C ( lQ ) comp a r e to a ma c ro s c op i c v i s c o s i t y o f a b out 1 0 9 Pa s f o r a n e n t a n g l ement n e t wo rk , and even h i ghe r v i s c o s i t i e s i f t h e ne two r k i s c r o s s l i nked (lQ) . Th i s p o i nt ha s b e e n u s e d t o und e r l i n e t h e i m ­ p o r t a n c e o f r e s e a r ch on sma l l PRC - wa t e r s y s t ems ( 75 ) , b a s e d o n a p o l y ­ me r s c i en c e a p p r o a c h ( 2 3 ) . Synthe t i c h i g h po lyme r s , a s we l l a s many h i gh - p o l yme r i c f o o d ma t e r i a l s , o f t en s uf f e r f rom t h e hand i c a p s of un ­ known , p o l yd i s p e r s e MW and MW d i s t r i b ut i on , and MWs a b o v e t h e i r e n ­ t ang l em e nt l im i t , i n wh i ch c a s e l o c a l v i s c o s i t y i s n o t e quiva l ent t o ma c r o s c o p i c v i s c o s i t y . Fo r s uch c a s e s o f MW s a b ove t h e e n t ang l ement l imi t , as ment i o n e d a b ove , a ha l v i ng o f MW r e s u l t s i n a 1 0 - f o l d r e ­ duc t i on i n the ma c r o s co p i c vi s c o s i ty o f the ne two rk ( lQ ) . In con­ t ra s t , s ma l l PRC s have known , mono d i s p e r s e va lue s o f MW , a l l b e l ow t h e e n t a ng l ement l imi t , s o that l o c a l v i s c o s i ty i s e quiva l ent t o ma ­ c ro s c o p i c v i s c o s i t y , and a ha l v i ng o f MW r e s u l t s o n l y i n a ha lving o f .

.

=

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I +

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en o o en -

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CJ o ..J

P al ), t s t y r e n e l o

,

LOG M W

+

NORMAUZATIO N CONSTANT

Figure 9. Plot of log viscosity + constant vs. log MW + normalization constant for a series of synthetic polymers, illustrating the generic behavior of polymers with MWs above and below the critical DP required for intermolecular entanglement and network formation. (Reproduced with permission from reference 10. Copyright 1980 John Wiley & Sons.)

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l o c a l v i s c o s i t y ( a s a l s o i l l u s t ra t e d in F i gu r e 9 f o r s yn t h e t i c p o l y ­ S u c h s ma l l PHC s me r s w i t h MWs b e l o w the i r ent ang l ement l imi t s ) ( 1 0 ) . o f f e r a g re a t va r i e t y and s e l e c t i on o f g l a s s - f o rming ma t e r i a l s f o r t h e s t udy o f v a r i ous a s p e c t s o f the non - equi l i b r i um behav i o r o f f o o d s ( 23 ) . I n t h e con t ext o f s t a r ch r e t r o g r a da t i o n a s a c o l l ap s e p ro c e s s ( 2 ) , r e t ro g ra da t i o n o f g e l a t i n i z e d s t a r ch invo lve s t h e r e c ry s t a l l i z a ­ I t ha s b e en t i on o f b o t h amy l o p e c t i n and amy l o s e ( 7 6 - 8 0 , 1 1 7 , 1 1 8 ) . d emon s t ra t e d f o r S H Ps that the m i n imum l i n e a r c ha i n l eng t h r e q u i r e d f o r i n t e rmo l e cu l a r ent ang l ement up on c o n c ent ra t i o n t o C g ' c o r r e s p on d s t o DPn - 1 8 a n d Mn - 3 0 00 (1) . S uf f i c i ent ly long l in e a r cha i n l en g t h ( DPn � 1 5 - 2 0 ) ha s a l s o b e e n c o r r e l a t e d w i t h i nt e rmo l e cu l a r n e t wo r k f o rma t i o n and the rmo reve r s i b l e g e l a t i on o f S H P s ( 2 . 3 . 6 8 . 1 1 4 ) and amy l o p e c t i n ( � ) , and with s t a r ch ( r e ) c ry s t a l l i z a t i o n ( 7 8 . 7 9 . 8 1 - 8 3 ) . I t ha s b e e n " s ug g e s t e d tha t , in a p a r t i a l l y c ry s t a l l i n e s t a r c h , SHP , o r amy l o p e c t in g e l n e t wo rk , the ex i s t e n c e o f random i n t e r c h a i n e n t a n ­ g l ement s i n amo rphous r e g i on s a n d " f r i n g e d mi c e l l e " ( J ) o r cha i n - f o l d ­ e d mi c ro c ry s t a l l i ne j un c t i o n z o n e s ( 6 8 ) e a ch r e p r e s e n t s a mani f e s t a ­ t i o n o f s uf f i c i en t l y l ong cha in l ength (1) . Th i s s ug g e s t i o n wa s s up ­ p o r t e d by o t h e r wo rk ( 7 0 . 7 1 . 7 9 , 1 2 0 ) wh i ch ha s s hown t h a t amy l o s e g e l s , wh i ch a r e p a r t i a l l y c ry s t a l l ine ( 8 3 ) , a r � f o rme d by c o o l i n g s o lut i o n s o f e n t ang l e d cha i n s . Fo r a q u e o u s s o lut i on s o f b o th h i gh MW amy l o s e ( 7 0 . 7 1 . 84 ) and amy l op e c t i n ( 8 1 . 8 5 ) , i nt e rmo l e cu l a r e n t a ng l e ­ ment and ne two rk f o rma t i o n have b e e n ev i d e n c e d b y l o g - l o g p l o t s o f v i s c o s i t y v s . c o n c ent r a t i o n w i t h a cha ra c t e r i s t i c b r e a k i n t h e c u rv e ( ana l o g o u s t o the b r e a k i n the curve s o f l o g v i s c o s i ty v s . l o g MW f o r t h e s yn t he t i c po lyme r s i n F i gu r e 9 ) , s uch tha t t h e s l o p e o f t h e l i n ­ e a r p o r t i o n above the s o - c a l l e d " c o i l ove r l ap " c o n c ent r a t i o n i s s t e ep ­ e r than the s l o p e o f the o t he r l i ne a r p o r t i o n a t l owe r c o n c e n t r a ­ t ions . F rom s uch a p l o t , Mi l e s e t a l . ( 7 0 ) have i d ent i f i e d a c r i t i ­ c a l min imum c onc ent r a t i on (� 1 . 5 w% amy l o s e ) f o r entang l em e n t o f 5 x 1 0 5 ) . The s e wo rke r s have s t a t e d h i gh - p o lyme r i c amy l o s e ( Mw t h a t amy l o s e g e l a t i o n r e q u i r e s ne two r k f o rma t i o n , and t h i s n e two r k f o rma t i o n r e q ui r e s entang l ement , and t h e y have c o n c l ud e d t h a t " po ly ­ me r e n t ang l ement i s imp o r t ant i n unde r s t a nding the g e l a t i o n o f amy ­ l o s e " ( 7 0 ) . A mo r e r e c ent s tudy o f aqueous amy l o s e g e l a t i o n b y G i d ­ l ey e t a l . ( 84 . 8 6 . 8 7 ) , us i ng nea r l y monod i s p e r s e amy l o s e s o f DP 2 5 0 2 8 0 0 , ha s i d e nt i f i e d a s omewha t l owe r c r i t i c a l g e l l i ng c o n c e n t r a t i o n o f - 1 . 0 w% . Th i s f i nding ha s b e e n c o r ro b o r a t e d i n a s ub s e q u e n t rhe ­ o l o g i c a l s t udy by Doub l i e r and Chop l i n ( 1 2 0 ) . G i d l ey e t a l . , wh i l e a c c e p t ing the c o n c e p t o f i nt e rmo l e c u l a r entang l ement in " s em i - d i l ut e " amy l o s e s o l u t i o n s advan c e d by Mi l e s e t a l . " ( 7 0 ) , have s ug g e s t e d tha t t h e l owe r g e l l ing c o n c e n t r a t i o n o f 1 . 0 w% r e s u l t s f rom t h e p r e domi ­ nant c o n t r i but i o n o f c rys t a l l i ne j unc t i on z o n e f o rma t i o n t o t h e g e l a ­ t i o n me chan i s m f o r amy l o s e ( 84 . 8 6 . 8 7 ) . The t ime - d ep endent g e l a t i o n o f amy l o s e f rom d i lut e a q u e o u s s o lu ­ t i o n i s g e n e ra l l y a g r e e d t o o c c ur i n two s t ag e s : a r e l a t i v e l y f a s t but f i n i t e s t a g e due t o v i s c o e l a s t i c n e t wo rk f o rma t i o n v i a e n t ang l e ­ ment ( wh i c h i s reve r s i b l e b y d i lut i o n but no t t h e rmo reve r s i b l e ) ; f o l ­ l owe d c l o s e l y by a s l owe r , but cont i nua l l y ma t u r ing , c ry s t a l l i z a t i o n ( i n a cha i n - f o l d e d o r extend e d - cha i n mo rpho l o g y ) p ro c e s s ( wh i c h i s t h e rmo reve r s i b l e above 1 0 0 ° C ) ( 7 0 , 7 1 , 7 8 , 7 9 , 8 1 , 8 8 - 9 0 , 1 2 0 ) . In con­ t ra s t , i n p a r t i a l l y c ry s t a l l ine , the rmo reve r s i b l e ( b e l o w 1 00 ° C ) , a q u e ­ o u s amy l op e c t i n g e l s , vi s c o e l a s t i c ne two rk f o rma t i o n ( wh i c h i s r e l a ­ t ive l y s l ow and t ime - d ependent ) i s mo r e c l o s e l y r e l a t e d t o t h e p r e s �

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e n c e o f m i c ro c ry s t a l l in e j un c t i o n s than t o ent ang l emen t s , a l t hough e n t ang l ement do e s o c cu r ( 7 8 , 8 1 , 8 2 , 1 1 7 , 1 1 8 ) ., S i n c e mo s t no rma l s t a r c h e s a r e 7 0 - 8 0 % amy l op e c t i n (21) , t h e i r g e l a t in i z a t i o n and r e t ro ­ g ra da t i o n p r o c e s s e s a r e domina t e d by the non - e qu i l i b r i um m e l t i n g and r e c ry s t a l l i z a t i o n b ehav i o r of amy l o p e c t i n ( 1 5 , 7 7 , 1 1 7 , 1 1 8 ) , a l t hough c o n t r i b ut i on s due t o amy l o s e can be o b s e rv e d ( 80 , 9 2 , 1 2 0 ) , Gene ra l l y , t h e e a r l y s t a g e s o f s t a r ch r e t ro g ra da t i o n a re domina t e d b y c h a i n ­ f o l d e d amy l o s e ( o f D P f rom a b out 1 5 t o a b o ut 5 0 a n d f o l d l en g t h a b out 1 0 0 A ( 7 8 , 8 1 , 9 3 » ; the l a t e r s t a g e s by extend e d - cha i n amy l op e c t i n (�) , ( 4 3 ) out e r b ranche s ( o f DP a b o ut 1 2 - 1 6 ( 8 1 , 9 4 » Exp e r iment a l evi d enc e , wh i ch s upp o r t s t he s e c o n c l u s i o n s a b o u t t h e t h e rmo r e v e r s i b l e g e l a t i o n me chan i s m f o r p a r t i a l l y c ry s t a l l in e p o l yme r i c g e l s o f s t a r c h , amy l op e c t i n , amy l o s e , a n d SHP s , ha s c ome f rom DSC s t ud i e s ( � ) , the favo r e d t e chn i que f o r eva l ua t i ng s t a r c h r e t ro g ra da t i on ( 9 5 ) , Ana l y s i s o f 2 5 w % SHP g e l s , s e t b y ove r n i ght r e f r i g e ra t i o n , h a s reve a l e d a s ma l l c rys t a l l ine m e l t i n g endo t he rm w i t h Tm 6 0 ° C CD , s imi l a r t o the cha ra c t e r i s t i c me l t i n g t ran s i t i o n o f r e t r o g r a d e d B - typ e whe a t s t a rch g e l s ( � ) , S im i l a r D S C r e s u l t s have b e e n r ep o r t e d f o r 2 0 w% amy l op e c t i n ( f rom waxy ma i z e ) g e l s ( � 9 6 ) , The s ma l l ext ent o f c ry s t a l l i n i t y i n S H P g e l s c a n b e i n c r e a s e d s i gn i f i c a n t l y by an a l t e rnat ive two - s t ep t emp e ra t u r e - cy c l i n g g e l a t i o n p ro t o co l ( 1 2 h r a t O ° C , f o l lowed b y 1 2 h r a t 4 0 ° C ) ( � ) , a d ap t e d f rom t h e o n e o r i g i na l l y d eve l o p e d by F e r ry ( 7 3 ) f o r g e l a t i n g e l s , and s ub ­ s e quent l y app l i e d by S l a d e e t a I , ( 2 9 ) t o r e t r o g r a d e d s t a r c h g e l s , I n many f undame nt a l r e s p e c t s , the t h e rmo r e v e r s i b l e g e l a t i o n o f a que ­ o u s s o l ut i o n s o f p o l yme r i c S H P s , amy l op e c t i n , amy l o s e , and g e l a t i n ­ i z e d s t a r c h i s ana l o gous t o the g e l a t i on - v i a - c ry s t a 1 I i z a t i o n o f s yn ­ t he t i c homo p O l yme r and c o p o lyme r - o rg an i c d i luent s y s t em s , d e s c r i b ed e l s ewhe r e ( � ) , Fo r the l a t t e r p a r t i a l ly c ry s t a l l i n e g e l s , t h e p o s s i b l y s imu l t aneous p r e s enc e o f random int e r ch a i n e n t a n g l em e n t s i n amo rphous r e g i o n s ( 9 7 ) and m i c ro c ry s t a l l in e j un c t i o n z o n e s ( 9 8 ) ha s b e e n r e p o r t e d , Howeve r , c o n t rove r s y exi s t s ( 9 7 , 9 8 ) ( a s i t a l s o do e s i n t h e c a s e o f amy l o s e ( 7 0 , 84 , 8 6 , 8 7 , 1 2 0 » ove r wh i ch o f t h e two c o n ­ d i t i o n s ( i f e i the r a l one ) m i ght b e t h e ne c e s s a ry a n d s uf f i c i en t o n e p r ima r i l y r e s p o n s i b l e f o r t h e s t ru c t u r e - vi s c o e l a s t ic p ro p e r t y r e l a ­ t i o n s h i p s o f s uc h p o l yme r i c s y s t ems , P a r t o f t h i s c o n t rove r s y c o u l d b e r e s o lv e d by a s imp l e d i lut ion t e s t ( 9 9 ) , wh i c h c o u l d a l s o b e a p ­ p l i e d t o p o l ys a c cha r i d e g e l s ( e , g , amy l o s e ) ; i , e , e n t ang l ement g e l s c a n b e d i s p e r s e d b y d i lut i o n a t r o om t emp e ra t ur e , wh i l e m i c ro c ry s t a l ­ In the con­ l i n e g e l s c anno t b e when room t emp e r a t u r e i s < Tm ( J ) , t ex t o f S H P s a s inhi b i t o r s o f c o l l a p s e p r o c e s s e s (1) , i t i s wo r t h ment i on i ng t ha t t h e l i t e ra t ure on S H P s a s ant i - s t a l ing i ng r e d i en t s f o r s t a r c h - b a s e d f o o d s ( r ev i ewed e l s ewhe r e ( � » i n c l ud e s a r e p o r t b y Krus i a n d Neukom ( 1 0 0 ) tha t ( no n - entang l i ng ) SHP o l i g ome r s o f D P n 3 - 8 ( i , e , w i t h i n t h e int e rme d i a t e r e g i o n I I o f F i g ur e 6 ) a r e e f f e c t ive i n inhi b i t ing , and n o t p a r t i c i p a t ing i n , s t a r c h r e c ry s t a l l i z a t i o n , An imp o r t a n t c o n s equenc e o f ent ang l ement and n e t wo rk f o rma t i o n i s t h e e f f e c t on the Tg tha t d e t e rmine s a l l d i f f u s i on - l im i t e d s t ruc ­ t u r a l and me chan i c a l r e l axa t i on p ro c e s s e s o f t h e s y s t em , As s hown s chema t i c a l l y in F i gu r e 1 0 ( 1 ) , wh i l e the mo l e cu l a r o r s e gment a l T g r ema i n s c o n s t a n t a b ove t h e entang l ement MW l im i t , t h e ne t wo rk T g , i , e , t h e ma c ro s c op i c , c o nt ro l l ing Tg o f t h e s up ramo l e cu l a r n e two r k ( t ha t wou l d a f f e c t I n s t ron me a s uremen t s o f t h e modu l u s , f o r i n s t a n c e ( 1 » , c o n t i nue s t o i n c r e a s e wi th i n c r e a s ing MW ab ove t h e e n t ang l ement MW , b e c a u s e of t h e i n c r e a s e d p ro b a b i l i t y of c r o s s l i nks ( 9 7 , 1 0 1 ) , �

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Thi s f a c t ha s maj o r s t ructura l and t extura l imp l i c a t i o n s f o r f o o d p o l yme r s ys t ems , b e caus e s uch s y s t em s w i t h MWs above t h e e n t ang l ement l im i t are c a p a b l e o f f o rmi ng f i b e r s , ne two rks , and g e l s : i . e . ma c ro ­ s c o p i c s t ru c t u r e s tha t can r e i n f o r c e and s upp o r t t he i r own we i gh t a g a i n s t g ravi ty ( 2 ) . A no t ewo r thy examp l e i s t h e g e l a t in i z e d whe a t s t a r c h - g lut e n ma t r ix o f b a k e d b r e a d . The e f f e c t iv e ne two r k Tg r e s p o n ­ s i b l e f o r me chan i c a l f i rmne s s o f f r e s h l y b a k e d b r e a d wou l d b e n e a r room t emp e ra t u r e f o r l ow extent s o f ne two rk f o rma t i o n ( i . e . t h e c o n ­ t r i but i o n d u e t o low ext ent s o f s t a rch r e t ro g ra da t i o n ) , we l l a b o v e r o om t emp e r a t u r e f o r ma ture ne two rks ( i . e . g r e a t e r ext e n t s o f r e t ro ­ g ra da t i o n ) , and e q uiva l en t t o Tg e l ( g e l me l � ing t emp e r a t u r e ) n e a r 6 0 0 e f o r s t a l e d b r e a d ( i . e . Tm o f f u l ly r e t r o g r a d e d B - t yp e whe a t s t a r c h ) , even though t h e unde r l y i ng T g f o r s e gment a l mo t i o n ( o f e i ­ t h e r s t a r ch o r g lut e n a t p l a s t i c i z i ng mo i s tu r e c o n t e n t s � Wg ' ) , r e ­ s p o n s i b l e f o r t h e p r e d ominant s e cond - o rd e r t he rma l t ra n s i t i o n , r e ­ ma i n s b e l o w o o e a t Tg ' ( � ) . S a c cha r i d e O l i �ome r s and Po lyme r s a s Mo i s t u r e Mana� ement A� e nt s . The b e twe en t h e s o lut e c o n c e n t ra t i o n a n d l i n e a r D P r e q u i r e ­ ment s f o r ent ang l ement and ne two rk f o rma t i o n , and i t s r e s u l t a n t e f ­ f e c t o n Tg ( mo l e c u l a r vs . n e t wo rk ) , a l s o ha s imp o r t a n t imp l i c a t i o n s f o r mo i s t u r e mana g ement by s a c cha r i d e o l i g ome r s a n d p o l ym e r s (�) . As exemp l i f i e d f o r t h e homo l o gous f ami ly o f amo rpho u s g l u c o s e o l i g o ­ me r s and p o l yme r s r e p r e s e � t e d by t h e comme r c i a l SHP s i n F i gu r e 6 , t h e r e a r e t h r e e d i s t ingui sh a b l e r e g ime s o f mo i s t u r e mana g em e n t , whi ch a r e ana l o g o us t o the t h r e e r e g i on s o f Tg v s . MW b ehavi o r s hown i n F i g u r e 4 a n d mi r ro r e d in F i gure 6 . As p e c t s o f mo i s t u r e manag ement r e l evant t o t he s e t h r e e r e g ime s of func t i ona l b ehav i o r i n c l ud e , e . g . , hyd ra t i o n , f r e e z i ng , d ry i ng , mo i s t ure m i g ra t i on , and b i o l o g i c a l s t a ­ b i l i t y ( 6 ) . The f i r s t r e g ime i n c l ud e s non - en t ang l i ng s o l ut e s o f l in ­ Fo r s uch sma l l s ug a r s a t a g iven wa t e r c o n c e n t r a t i o n , ear DP < 3 . t h i s mo i s t u r e mana g ement r e g ime i s cha ra c t e r i z e d by l ow a pp a r e n t ( no n - e q u i l i b r i um ) re l a t ive vap o r p r e s s u r e ( RVP ) ( � ) , v e ry l a rg e o s ­ mo t i c d r iv i ng f o r c e t o t a k e up wa t e r , l ow l o c a l v i s c o s i t y , and o n l y a s ma l l b a r r i e r t o l o c a l t rans l a t i o na l and ro t a t iona l d i f f u s i o n . The s e c o nd r e g ime , f o r non - entang l i ng s o l ut e s o f DP 3 t o 1 7 , i s c ha ra c ­ t e r i z e d b y high app a r ent RVP , sma l l o s mo t i c d r iving f o r c e t o t a ke up wa t e r , h i gh l o c a l v i s c o s i t y , and a l a rg e ba r r i e r to l o c a l t ra n s l a ­ t i ona l and ro t a t i ona l d i f fus i o n . The thi rd r e g ime , f o r e n t ang l ing s o l ut e s o f D P » 1 7 , i s cha ra c t e r i z e d by ve ry h i g h app a r e nt RVP , v e ry l a rg e l o c a l o smo t i c d r i v i ng f o r c e t o s we l l , very low l o c a l v i s c o s i t y , and e s s en t i a l l y no b a r r i e r t o l o c a l t rans l a t i ona l and r o t a t i o na l d i f ­ f u s i o n ( 2 ) . In thi s c o n t ext , i t i s i n t e r e s t i ng t o no t e t ha t o u r f ind ­ i n g o f DPn 1 8 f o r the m i n imum DP f o r entang l ement and n e t wo rk f o r ­ ma t i o n b y comme r c i a l S H P s , a r e s u l t i d e nt i f i e d f rom t h e p o l yme r c ha r ­ a c t e r i z a t i o n ana l y s i s r e p r e s ent e d b y F i gure 6 , ha s b e e n c o n f i rm e d by F rom a r e ve a l i n g f i nding r e c ent ly repo r t e d by Rado s t a et a l . ( 1 1 4 ) . t h e i r s t udy of the wa t e r s o rp t i o n b e hav i o r of ma l t o d e x t r i n s , t h e y c o n c l ud e d t ha t " the t rans i t i o n b e tw een " po l yme r " and " o l i g ome r " b e ­ hav i o r und e r s o rp t i o n c o nd i t i on s i s l o c a t e d i n the r e g i o n o f DPn va l ­ u e s b e tw e e n 6 0 and 16 . In t h i s DPn r e g i on , t h e s h i f t ing f rom r e ­ s t r i c t e d s we l l ing [ by wha t Rado s t a e t a l . re f e r t o a s a " s o rp t i on g e l " ] t o s o l ut i on und e r s o rp t i on cond i t i o n s t a k e s p l a c e " (1 1 4 ) . A c o n c e p t ua l r ep r e s ent a t i o n o f the t h r e e r e g ime s o f mo i s t u r e mana g ement i s s hown i n F i gure 1 1 ( 2 ) . Fo r a g iven t emp e ra t u r e ( e . g .

;e l a t i on s h i p

-

-

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NETWORK Tg

0 . 0

..�----- SEGMENTA L Tg ENTANGLEME NT

�

REGION

0

�

..

- 50

MW - 3000 DP - 1 8 DE < 6

MOLECULAR WEIGHT

Figure 10. Schematic plot of Tg (or Tg') vs. molecular weight (modeled after the data plot for SHPs in Figure 6), which illustrates that, while the segmental Tg remains constant with increasing MW for MWs above the entanglement limit, the network Tg continues to increase monotonically with increasing MW above the entanglement MW limit. (Reproduced with permission from reference 7. Copyright 1991 Plenum.) T > > Tg . ., ' . . . :. . . .

� . .. : .

.

. ' . . . . . , . .. .

II

T > Tg

III

N ETWORK Tg > T > Tg

-----

Figure 11. Conceptual representaion of the three regimes of moisture management by a homologous family of saccharide polymers (e.g. the SHPs in Figure 6):1. at T > > Tg of a concentrated solution of non-entangling saccharide oligomers of linear DP < 3; II. at T > Tg of a less concentrated solution of non-entangling saccharide polymers of linear DP 3 to 17.; III. at network Tg > T > Tg of a dilute solution (but above the critical concentration for entanglement) of entangling saccharide high polymers of linear DP > > 17. (Reproduced with permission from reference 7. Copyright 1991 Plenum.) =

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r o om t emp e ra t u r e ) and t ime ( e . g . a p ra c t i c a l exp e r iment a l t im e f rame ) , T i s we l l a b ove Tg f o r c o n c ent ra t e d s o l ut i o n s o f r e g ime I s o l u t e s , and s uc h a s y s t em wo u l d b e s ubj e c t t o v i s c o u s l i qu i d f l o w due t o g ravi ty . In r e g ime I I a t T > Tg , appa rent RVP i s n o t d e p re s s ­ e d a s much a s in r e g ime I , b e caus e t h e r e a r e f ewe r s o l u t e mo l e c ul e s i n s o l u t i o n . Howeve r , the i r h i ghe r l i n e a r D P r e s u l t s i n h i g h e r l o c a l v i s c o s i t y , wh i ch in turn r e s ul t s in a l a r g e r b a r r i e r t o l o c a l d i f f u ­ In r e g im e I I I s i o n a n d r e d u c e d v i s cous l i q u i d f l ow due t o g ray i t y . ( f o r a s o l u t e c o n c ent r a t i o n h i g h enough t o a l l ow e n t a ng l em e n t ) , a t n e t wo rk T g > T > mo l e cu l a r Tg , the r e i s e l a s t i c r e s i s t a n c e t o f l ow , and t h e g e l i s a b l e t o s upp o r t i t s own we i g h t a g a i n s t t h e f o r c e o f g ravi t y ( Z ) . I n t h i s r e g ime , the r e i s e s s en t i a l l y n o b a r r i e r t o l o c a l d i f f us i o n , s o a sma l l mo l e c u l e s uch a s wa t e r o r a d y e mo l e cu l e c a n d i f f u s e f r e e l y i n the g e l ne two rk ( 1Ql ) . H e nc e , r e g ime III man i ­ f e s t s v e ry h i gh a p p a rent RVP . D e s p i t e t h i s , howev e r , t h e r e i s a v e ry l a rg e l o c a l o smo t i c d r iv i ng f o r c e t o t a ke up wa t e r , no t o n l y v i a hy ­ g ro s c o p i c i t y but v i a swe l l ing , t h e l a t t e r due t o t h e me c h a n i c a l r e ­ s i s t a n c e o f t h e ent ang l ed ne two rk t o s h r inka g e ( Z ) . Th i s me c ha n i c a l r e s i s t a n c e t o s h r inka g e , wh i ch i s ana l o g ous t o hyd r au l i c r e s i s t a n c e t o wa t e r r emova l , ha s an e f f e c t o n t h e l o c a l c h em i c a l p o t en t i a l o f t h e s o lvent , ana l o gous t o a n a dd i t i o n t o t h e o smo t i c p r e s s ur e ( 1 0 3 ) . Thus , wh i l e t h e r e i s a v e ry l a rg e d r iv i ng f o r c e t o t a ke up wa t e r v i a s we l l i ng i n r e g ime I I I , a n d a no rma l , c l a s s i c a l o smo t i c d r i v i n g f o r c e t o t a ke up wa t e r v i a hyg ro s c op i c i t y i n r e g ime I , t h e r e i s a much l o w ­ e r d r iv i n g f o r c e t o t a k e u p wa t e r v i a c l a s s i c a l o smo t i c p r e s s u r e e f ­ f e c t s i n r e g ime II , b e c a us e o f t h e a b s e n c e o f a s we l l i ng f o r c e due t o e n t ang l ement ( Z ) . To i l l u s t ra t e the c o n s e quenc e s o f the t h r e e r e g ime s o f f un c t i o n ­ a l b e hav i o r o f s a c cha r i d e mo i s t u r e mana g ement a g e nt s , o n e c o u l d us e r e s u l t s f rom , e . g . , d rying o r f r e e z ing exp e r iment s . D ry i ng and f r e e z ­ i n g a r e equiva l ent d i f f us i on - l im i t e d p ro c e s s e s in t h e s en s e t h a t b o t h i nvo l v e remova l o f wa t e r v i a pha s e s ep a ra t i o n ; i n d ry i n g b y i n c r e a s ­ i n g t h e t emp e r a t u r e t o p ro d u c e wa t e r vapo r , and i n f r e e z i n g by d e ­ c r e a s i n g t h e t emp e r a t u r e t o p ro duc e i c e (�) . Muh r a n d B l an s h a r d ( 1 04 ) have me a s ur e d the r e l a t ive r a t e s o f l i n e a r i c e f ro n t a dv a n c e ­ m e n t a t s ub z e ro t emp e r a t ur e s i n aqueous s o l u t i o n s o f 3 5 w% s uc r o s e w i t h and w i t hout a d d e d po ly s a c ch a r i d e " s t a b i l i z e r s " . The i r r e s ul t s s howe d c o n c l u s ive l y t ha t t h e ra t e s dep end c r i t i ca l ly o n t h e p r e s e n c e o r a b s e n c e o f a g e l n e t wo r k , even f o r exa c t ly t h e s ame f o rmul a t i on . Fo r t h e s o lut i o n o f s uc ro s e a l one a t T » T g ' [ r e g ime I ] , t h e r e l a ­ t iv e r a t e o f i c e f ront a dvanc ement wa s 6 . 0 . [ I t wou l d have b e en e s ­ s ent i a l l y z e ro a t T < Tg ' . ] At t h e s ame t emp e r a t u r e , t h e r a t e wa s 4 . 1 i n a s u c ro s e s o l u t i o n c o n t a ining 0 . 7 5 w% non - en t a n g l i ng ( i . e . no n - g e l l i ng ) Na a l g i na t e [ re g ime I I ] , but o n l y 1 . 0 i n a s u c ro s e s o l u ­ t i o n c o n t a i n i n g 0 . 7 5 w % ent ang l i ng ( i . e . g e l l in g ) C a a l g i na t e [ r e g im e I I I ) . Thus , whe n t h e r e wa s a hyd rau l i c r e s i s t a n c e t o wa t e r r emova l , due t o t h e r e s i s t a n c e o f the C a a l g i na t e g e l n e two rk t o s h r i n ka g e , t h e ra t e o f i c e f ront a dvanc ement wa s d r ama t i c a l l y r e du c e d (Z) . By ana l o gy t o o t h e r mo i s t u r e mana g ement p ro b l em s i nvo l v i ng d i f ­ f u s i o n - l im i t e d p r o c e s s e s ( e . g . " wa t e r a c t iv i t y " c o n t ro l , t ex t u r a l s t a b i l i z a t i o n ) , e n t a ng l ing , n e t wo r k - f o rming s a c cha r i d e h i g h p o l ym e r s f rom r e g ime I I I c a n b e us e d a s f unc t i ona l a dd i t ive s t o , e . g . , r e t a rd mo i s t u r e m i g ra t i on in b a k e d g o o d s , r e t a i n c r i s p ne s s o f b r e a kf a s t c e ­ r e a l s , and r e du c e s o g g i ne s s o f p a s t r i e s and p i e c rus t s ( � ) .

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C ryo s t a b i l i z a t i o n T e chno l o gy - C o l l ap s e Phenomena - Func t i o na l i ty o f S a c ch a r i d e Po lyme r s a s C o l l a p s e Inh i b i t o r s " C ryo s t a b i l i z a t i o n t e chno l o gy " ( 1 , 2 , 1 8 - 2 2 ) r ep r e s en t s a n e w c o n c e p t u ­ a l a p p r o a ch t o a p r a c t i c a l i ndus t r i a l t e chno l o gy f o r t h e s t a b i l i z a ­ t i on d u r i n g p ro c e s s i ng and s t o ra g e o f f ro z en , f r e e z e r - s t o r e d ; a n d f r e e z e - d r i e d f o o d s , Th i s t e chno l o gy eme r g e d f rom o u r f o o d p o l yme r s c i en c e r e s e a r c h app r o a ch and deve l o p e d f rom a f undamen t a l und e r s t and ­ i n g o f t h e c r i t i c a l phys i c o chemi c a l and the rmome c h a n i c a l s t ru c t ur e ­ p ro p e r t y r e l a t i o n s h i p s t h a t und e r l i e t h e b ehavi o r o f wa t e r i n a l l C ryo ­ n o n - e q u i l i b r i um f o o d s y s t ems a t s ub z e ro t emp e r a t ur e s ( 3 8 , 4 0 ) . s t a b i l i z a t i o n p ro v i d e s a means o f p ro t e c t ing p ro d uc t s , s t o r e d f o r l o n g p e r i o d s a t typ i c a l f r e e z e r t emp e ra t ure s ( e . g . T f = - 1 8 ° C ) , f rom d e l e t e r i o u s c h a ng e s in t exture ( e . g . " g r a i n g rowt h " of i c e , s o l u t e c rys t a l l i z a t i o n ) , s t ru c t u r e ( e . g . c o l l ap s e , s h r i nk a g e ) , a n d c h em i c a l c omp o s i t i o n ( e . g . enzyma t i c a c t i v i t y , ox i d a t i v e r e a c t i o n s s uc h a s f a t r a nc i d i ty , f l av o r / c o l o r d e g rada t i o n ) . Such c h a ng e s a re exa c e rb a t e d i n many t yp i c a l f a b r i c a t e d f o o d s who s e f o rmu l a s a r e dom i na t e d b y l o w MW s a c ch a r i d e s . The key t o t h i s p r o t e c t i o n , a n d r e s u l t ing i mp rove ­ ment i n p ro duc t qua l i t y and s t o ra g e s t a b i l i ty , l i e s i n c o n t r o l l ing t h e s t ru c t u r a l s t a t e , by c o n t ro l l i ng t h e phys i c o chemi c a l a n d t h e rmo ­ me chani c a l p ro p e r t i e s , o f the f r e e z e - c o n c ent r a t e d amo rphous ma t r i x s ur ro und ing t h e i c e c rys t a l s i n a f ro z e n s ys t em . As a l l ud e d t o e a r ­ l i e r , t h e impo r t a n c e o f t h e g l a s s y s t a t e o f t h i s maxima l ly f r e e z e ­ c o n c ent r a t e d s o l ut e - UFW ma t r ix and the s p e c i a l t e chno l o g i c a l s i gn i f i ­ c a n c e o f i t s p a r t i c u l a r Tg , i . e . Tg ' , r e l a t i v e t o T f , h ave b e en d e ­ s c r i b e d and i l l us t ra t e d by s o lut e - wa t e r s t a t e d i a g r ams s uc h a s t h e i d e a l i z e d o n e i n F i gu r e 1 2 ( � ) . U p o n a f o und a t i o n o f p i on e e r i n g s tud i e s o f the l o w t emp e r a ture the rma l p r op e r t i e s o f f ro z e n a q u e o u s mo d e l s y s t ems by Luye t , Ma cKenz i e , R a smus s en ( 3 2 , 3 4 . 4 7 - 4 9 , 1 0 5 ) , and F ra n k s ( 3 1 . 3 8 - 4 1 ) , an ext ens ive c ryo s t a b i l i z a t i o n t e c hno l o g y d a t a b a s e o f D S C r e s u l t s f o r c a rbohyd r a t e and p r o t e i n f o o d i ng r e d i e n t s h a s b e en bui l t ( 1 - 5 , 1 8 - 2 3 . 2 6 ) . As revi ewe d e a r l i e r , D S C r e s u l t s f o r t h e c ha ra c t e r i s t i c Tg ' v a lue s o f indivi dua l s a c cha r i d e s o l ut e s h ave d e m ­ o n s t ra t e d t h a t Tg ' i s a func t i on o f MW f o r b o t h homo l o g o u s a n d qua s i ­ homo l o g o u s f ami l i e s o f wa t e r - c omp a t i b l e monome r s , o l i g ome r s , a n d h i gh p o l yme r s . Examp l e s o f how t h e s e l e c t i o n and us e o f a p p r o p r i a t e i n ­ g r e d i e n t s ( e . g . l o w D E SHP s ) in a f a b r i c a t e d p ro duc t have a l l ow e d t h e f o o d t e chno l o g i s t to man i pu l a t e t h e c omp o s i t e Tg ' , a n d thus d e l i b e r ­ a t e l y f o rmu l a t e t o e l eva t e Tg ' r e l a t iv e t o T f a n d s o enhan c e p ro duc t s t a b i l i t y , have b e en d e s c r i b e d ( 1 - 5 . 1 8 - 2 3 . 2 6 - 2 8 ) , a s r e v i ewe d b e l o w . Muc h o f our und e r s t anding o f the the rma l a n d t h e rmome c h a n i c a l p ro p e r t i e s o f c o n c ent r a t e d a q ueous s o l ut i ons ha s b e e n d e r iv e d f rom e x t e n s i v e s t ud i e s of sma l l g l a s s - f o rming s a c c h a r i d e s at s ub z e ro t em ­ p e r a t u r e s . The s e s t ud i e s , whi c h b e g a n ove r 5 0 ye a r s a g o w i t h t h e s em i n a l wo rk o f Luy e t ( 1 0 5 ) , have e s t a b l i s h e d t ha t T r , t h e mi c r o s c o p ­ i c a l ly o b s e rv e d t emp e r a t u r e o f i r rup t ive i c e r e c rys t a l l i z a t i o n i n s u c h g l a s s - f o rming s y s t ems o f l o w MW s ug a r s and p o l yo l s ( 3 1 , 3 2 . 3 8 , 4 7 4 9 ) , c o i n c i d e s w i t h the s o lut e - s p e c i f i c Tg ' mea s ur e d by t h e rma l o r t h e rmome c h a n i c a l a n a lys i s ( l . 2 , 1 9 . 2 2 . 4 0 . 4 2 .. 1 0 6 , 1 0 7 ) . I t ha s a l s o b e e n r e c o gn i z e d t ha t i c e r e c rys t a l l i z a t i o n i s but o n e o f many p o s s i ­ b l e m a n i f e s t a t i o n s ( r e f e r r e d t o a s c o l l a p s e phenomena ) o f t h e dynam i ­ c a l l y c o n t ro l l e d b e havi o r o f a queous g l a s s e s and rub b e r s , wh i ch exi s t a t s ub z e ro t emp e ra t u r e s i n k i ne t i c a l l y c o n s t ra i n e d , me t a s t a b l e s t a t e s r a t h e r t h a n equi l i b r i um t h e rmodynam i c pha s e s ( 1 - 5 , 1 8 - 2 3 ) . G e n e r i c

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Figure 12. Schematic state diagram of temperature vs. w% solute for an aqueous solution of a hypothetical small carbohydrate (representing a model frozen food system), illustrating the critical relationship between Tg' and freezer temperature (Tf), and the resulting impact on the physical state of the freeze-concentrated amorphous matrix. (Reproduced with permission from reference 18. Copyright 1988 Cambridge.)

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u s e o f t h e t e rm " rubb e r " in t h i s cont ext d e s c r i b e s a l l g l a s s - f o rm i n g l i q u i d s a t T g < T < Tm , i n c l ud i ng b o t h mo l e cu l a r rubb e r s ( v i s c o u s l i qui d s ) o f low MW monome r s a n d o l i g ome r s a n d v i s c o e l a s t i c n e two r k ­ f o rming rub b e r s o f ent ang l ing h i g h po lyme r s . A c omp a r i s on o f l i t e ra t u r e va lue s o f s ub z e ro c o l l a p s e t ra n s � t � o n t emp e r a t u r e s ( Tc ) f o r an ext ens ive l i s t o f wat e r - c omp a t i b l e monome r s and p o lyme r s ha s e s t a b l i s h e d t h e f undament a l i d en t i t y o f T g ' w i t h t h e m i n imum o n s e t t emp e ra t u r e s o b s e rved f o r va r i ous s t ru c t ur a l c o l l ap s e and r e c rys t a l l i z a t i o n p r o c e s s e s ( 1. 2 . 1 15 ) , f o r b o t h mo d e l s o lut i o n s a n d r e a l s y s t em s o f f o o d s , a s we l l a s p h a rma c e ut i c a l s a n d b i o l o g i c a l s ( 3 8 . 4 2 . 1 0 6 . 1 0 8 . 1 0 9 ) . The Tc and T r va lue s o f f ro z e n o r vi t r i f i e d s amp l e s , t a bu l a t e d e l s ewh e r e ( 1 . 2 . 2 2 ) , a re t yp i c a l l y d e t e rm i n e d b y c ryomi c r o s c o p y , t h e rma l ana l y s i s , o r e l e c t r i c a l r e s i s t en c e me a s ur e ­ ment s ( 2 2 and r e f s . the r e i n ) , on an exp e r iment a l t ime s c a l e s imi l a r t o t ha t f o r T g ' b y our D S C method ( 1 0 6 . 1 0 9 ) . A c omp r eh e n s i v e l i s t o f c o l l ap s e p ro c e s s e s ( Ta b l e I ) , a l l o f wh i ch a r e gove rned b y Tg ' o f f ro z en s y s t ems ( o r a h i ghe r T g p e r t a i n i ng t o l o w mo i s t u r e s ys t em s p r o c e s s e d o r s t o r e d a t T > O ° C ) a n d invo lve p o t ent i a l l y d e t r iment a l p l a s t i c i z a t i o n by wa t e r , ha s b e en ident i f i ed and e l u c i d a t e d ( 1 - 5 . 1 8 2 2 . 2 6 ) . The two p a r t s o f Tab l e I , taken t o g e t he r , empha s i z e how t h e Tg va l ue s r e l evant t o b o t h low a n d h i gh t emp e ra t u r e c o l l ap s e p r o c e s s ­ e s a r e s y s t ema t i c a l ly r e l a t e d through the c o r r e s po n d i ng wa t e r c o n ­ t ent s , t hus i l lus t ra t ing how t h i s i nt e rp r e t a t i o n o f c o l l ap s e p h enome ­ na ha s b e e n g e n e ra l i z e d to i n c l ude b o t h h i gh t emp e r a t u r e/ l ow mo i s t u r e and l o w t emp e ra t u r e/h igh mo i s ture f o o d p roduc t s and p ro c e s s e s (� 22 26) P r ev i ou s v e r s i o n s o f Tab l e I ( 2 2 . 2 6 ) c o nt a i n e d ext e n s ive r e f e re n c e s f rom the food s c i en c e and t e chno l o g y l i t e ra t ur e to s p e c i f ­ i c examp l e s o f b o t h low t emp e r a t ure/h i g h mo i s t u r e and h i g h t emp e r a ­ t u r e / l ow mo i s t u r e c o l l ap s e p r o c e s s e s . I n a l l c a s e s , a p a rt i a l l y o r c omp l e t e l y amo rphous s y s t em in the me chani c a l s o l i d s t a t e a t T < T g and l o c a l vi s c o s i t y > ng a t Tg wou l d b e s t a b l e a g a i n s t c o l l a p s e , w i t h ­ i n t h e p e r i o d o f exp e r iment a l mea s urement s o f Tg , T c , and/o r T r . I n c r e a s e d mo i s t u r e con t ent ( and concomi t a n t p l a s t i c i z a t i o n ) wou l d l e a d t o d e c r e a s e d s t a b i l i t y and she l f - l i f e , a t any p a r t i c u l a r s t o ra g e The va r i ous phenomeno l o g i c a l t h r e s ho l d t emp e r ­ t emp e ra t u r e (3 7 . 1 15) . a t u r e s f o r the d ive r s e c o l la p s e p r o c e s s e s l i s t e d i n Tab l e I a l l c o r ­ r e s pon d t o the p a r t i c u l a r Tg ' o r o t h e r T g r e l evant t o t h e s o l ut e ( s ) . s y s t em and i t s c o n t ent o f p l a s t i c i z i ng wa t e r . Our i nt e rp r e t a t i o n o f the phys i c o chemi c a l b a s i s o f c o l l ap s e ha s a l s o p ro v i d e d i n s i g h t s to the emp i r i c a l c o un t e rme a s u r e s t ra d i t i o na l ly emp l o y e d t o i nh i b i t c o l l ap s e p r o c e s s e s tV . In p ra c t i c e , c o l l ap s e i n a l l i t s d i f f e r e n t mani f e s t a t i o n s c a n b e p r event e d , a n d f o o d p ro duc t q ua l i t y , s a f e t y , and s t ab i l i t y ma i n t a i ne d , by t h e f o l l o w i n g m e a s ur e s ( 1) : 1 ) s t o ra g e a t a t emp e r a t u r e b e low o r s uf f i c i ent l y n e a r T g ( 1 1 0 ) ; 2 ) d e l i b e r a t e f o rmu l a t i o n to i n c r e a s e T c ( i . e . Tg ) t o a t emp e r a t u r e a b ove o r s uf f i c i en t l y n e a r the p r o c e s s ing o r s t o ra g e t emp e ra t ur e , by i n c r e a s i ng the c omp o s i t e Mw of the wa t e r - c omp a t i b l e s o l i d s i n a p ro d ­ u c t m i x t u r e , o f t e n a c c omp l i s h e d by add ing " p o l yme r i c ( c ryo ) s t a b i l i z ­ e r s " ( 1 , 2 . 1 8 ) s uc h a s l ow DE SHP s o r o t he r h i gh MW c a r b o hyd ra t e s , p r o t e i n s , o r c e l l u l o s e and p o l y s a c cha r i d e gum s t o f o rmu l a t i on s domi ­ na t e d by l o w MW s o l ut e s such a s s uga r s and/o r p o l yo l s ( 3 5 - 3 7 . 1 1 0 ) ; and 3 ) in hyg ro s c op i c g l a s s y s o l i d s and o t he r low mo i s t u r e amo rphous f o o d s y s t ems e s p e c i a l l y p rone t o the d e t r iment a l e f f e c t s of p l a s t i c i ­ z a t i o n b y wa t e r ( i n c l ud i ng va r i ous f o rms o f " candy " g l a s s e s ) ( 1 1 0 ) , a ) r e duc t i on o f the r e s i dua l mo i s ture cont ent to � 3 % d u r i n g p r o c e s s .

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i n g , b ) p a c ka g i ng in s up e r i o r mo i s ture - ba r r i e r f i lm o r f o i l to p r e ­ vent mo i s t u r e up take dur i ng s t o ra g e , and c ) avo idanc e o f exc e s s iv e t emp e r a t u r e and humi d i t y ( Z 2 0 % R . H . ) c o nd i t i o n s dur ing s t o r a g e ( � 1 1 0 ) . The s uc c e s s f u l p ra c t i c e o f the p r inc i p l e s o f c ryo s t a b i l i z a t i on t e chno l o g y ha s o f t e n b e e n s hown t o r e ly on the c r i t i c a l ro l e o f h i g h ­ p o l yme r i c s a c cha r i d e s a n d p r o t e i n s i n p r event i ng c o l l ap s e ( by r a i s i n g t h e comp o s i t e Mw a n d r e s u l t ing Tg ' o f a f ro z e n p roduc t r e l a t ive t o T f ) and t o app l y e q ua l l y we l l t o l ow mo i s t u r e f o o d s , s uc h a s amo r ­ phous , f r e e z e - d r i e d powd e r s ( 1 - 5 . 1 8 - 2 2 . 2 6 - 2 8 . 4 2 ) . C o l l ap s e p ro c e s s e s dur i ng f r e e z e r s t o ra g e a r e p romo t e d b y t h e p r e s e n c e o f h i g h c o n t e n t s o f low MW s a c cha r i d e s o f c ha ra c t e r i s t i c a l ly l o w Tg ' and h i g h Wg ' in the c ompo s i t i o n o f many f ro z en f o o d s ( e . g . de s s e r t s ) ( 1 . 2 . 1 8 - 2 2 ) . The f undament a l phys i c o c h emi c a l b a s i s o f t h e c ryo s t a b i l i z a t i o n o f s uc h p roduc t s ha s b e e n i l l u s t ra t e d b y t h e i d e a l ­ i z e d s t a t e d i a g ram ( mo d e l e d a f t e r one f o r f ruc t o s e - wa t e r (l» s hown i n F i gu r e 1 2 , wh i ch ha s a l s o b e e n us e d t o exp l a i n why Tg ' i s t h e k e y ­ s t one o f the c o n c e p t ua l f ramewo rk o f thi s t e c hno l ogy ( 1 8 - 2 2 ) . A s , s hown i n F i gure 1 2 , the ma t r ix s ur round ing t h e i c e c rys t a l s i n a max ­ ima l ly f ro z e n s o lut i o n i s a s up e r s a t u ra t e d s o lut i o n o f a l l t h e s o lut e in t h e f ra c t i o n o f wa t e r r ema i n i ng unf ro z e n . Th i s ma t r ix exi s t s a s a g l a s s o f c o n s t a n t compo s i t i o n a t any t emp e r a t u r e b e l o w Tg ' , b u t a s a r ub b e ry f l u i d o f l owe r c o n c e n t r a t i o n a t h i g h e r t emp e ra tu r e s b e tween Tg ' and the Tm o f i c e . I f t h i s amo rphous ma t r ix i s ma i n t a i n e d a s a me c ha n i c a l s o l i d , a s a t T f 1 < Tg ' and l o c a l v i s c o s i t y > � a t Tg , t h e n d i f f u s i on - l im i t e d p ro c e s s e s that typ i ca l ly r e s u l t i n r e du c e d q ua l i ty and s t ab i l i t y c a n b e v i r t ua l l y p r even t e d o r , a t l e a s t , g r e a t l y i nh i b ­ i t e d . Thi s phys i c a l s i t ua t i o n ha s b e en i l l u s t ra t e d by s c ann i ng e l e c ­ t ro n mi c ro s copy pho t o g raphs (la) o f f ro z en mo d e l s o l ut i on s , whi c h s how s ma l l , d i s c r e t e i c e c rys t a l s emb e d d e d and immo b i l i z e d i n a c o n ­ t inuou s amo rphous ma t r ix o f f re e z e - c o n c e nt r a t e d s o lut e - UFW whi ch ex ­ i s t s a s a g l a s s y s o l i d a t T < Tg ' . The s i t ua t i o n ha s b e e n d e s c r i b e d b y ana l o gy t o an unyi e l d i ng b l o c k o f window g l a s s w i t h c a p t u r e d a i r bubb l e s (la) . I n con t ra s t , s t o ra g e s t a b i l i ty i s r e duc e d i f a n a t u r a l ma t e r i a l i s imp ro p e r ly s t o r e d a t t o o h i g h a t emp e ra t ur e , o r a f a b r i ­ c a t e d p ro d u c t i s imp ro p e r l y f o rmu l a t e d , s o t h a t t h e ma t r ix i s a l l owed to exi s t as a rub b e ry f l u i d a t Tf 2 > Tg ' ( s ee Figure 1 2 ) , i n and t h rough whi ch d i f fus i o n is f r e e t o o c cur . Thus , t h e Tg ' g l a s s ha s b e en r e c o g n i z e d a s the mani f e s t a t ion o f a kine t i c b a r r i e r t o any d i f ­ f u s i on - l imi t e d p ro c e s s ( 1 , 4 0 ) , inc l ud i ng furthe r i c e f o rma t i o n ( w i t h ­ i n t h e exp e r iment a l t ime f rame ) , d e s p i t e t h e c o n t inued p r e s e n c e o f UFW a t a l l t emp e ra t u r e s b e l ow Tg ' . The d e l u s ive " hi g h a c t i va t i o n e n e r g y " o f t h i s k i ne t i c b a r r i e r t o re l axa t i o n p r o c e s s e s ha s b e e n i d e n ­ t i f i e d a s t h e ext reme t emp e r a t u r e depende n c e t h a t gove rns chang e s i n l o c a l v i s c o s i t y a n d f r e e vo l ume j us t above Tg ( 2 2 ) . Th i s p e r s p e c t ive o n t h e g l a s s at Tg ' - C g ' as a me chani c a l b a r r i e r ha s p ro v i d e d a l ong ­ s o ught t h e o re t i c a l exp l a na t ion o f how und e r co o l e d wa t e r c an p e r s i s t ( ov e r a r e a l i s t i c t ime p e r i o d ) i n a s o lut i o n i n t h e p r e s en c e o f i c e c rys t a l s ( 1 8 , 2 0 , 2 2 ) . R e c o g n i z ing the s e f a c t s , and r e l a t in g t hem t o t h e c o n c e p t ua l f ramewo rk de s c r i b e d by F i gu r e 1 2 , o n e c a n a pp r e c i a t e why t h e t emp e ra t ur e o f t h i s g l a s s t rans i t i o n i s s o imp o r t ant t o a s ­ p e c t s o f f ro z en f o o d t e chno l o g y invo lving f r e e z e r s t o ra g e s t a b i l i t y , f r e e z e - c o n c e n t r a t i o n , and f re e z e - d rying ( 3 8 . 4 0 . 4 2 , 1 0 7 . 1 1 5 , 1 1 6 ) , wh i c h a r e a l l s ub j e c t t o va r i ous r e c rys t a l l i z a t i o n and c o l l ap s e phe nomena at T > Tg ' ( 1..1. ) . The o p t imum Tf f o r a na tura l ma t e r i a l o r o p t imum f o rmu l a f o r a

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f a b r i c a t e d p ro d u c t i s d i c t a t e d by the Tg ' cha r a c t e r i s t i c o f a p a r t i c ­ u l a r comb i n a t i o n o f s o l ut e s and UFW i n the ma t r ix c omp o s i t i o n o f t h e g l a s s a t Tg ' . C g ' ( 1 . 2 . 1 8 - 2 2 ) . Tg ' i s gove r n ed in t urn by t h e Mw o f t h i s p a r t i cu l a r ma t r ix c omb i na t i on i n a c omp l ex f o o d s ys t em ( � 4 0 ) . Mo r e ov e r , the dynami c b ehav i o r o f rub b e ry f ro z en f o o d p ro d uc t s d u r i ng s t o ra g e above Tg ' i s d rama t i c a l ly t emp e ra t ur e - d e p e n d e n t , a n d t h e ra t e s o f d i f f u s i o n - l imi t e d d e t e r i o ra t i o n p r o c e s s e s a r e quant i t a ­ t iv e l y d e t e rm i n e d by the t emp e rature d i f f e r e n c e A T Tf - Tg ' ( i n D C ) ( 3 . 1 8 ) . The s e r a t e s have b e en s hown t o i n c r e a s e exp o n e n t i a l l y w i t h i n c r e a s i n g A T , i n a g r e ement w i t h WLF , r a t h e r than Ar r h en i u s , k i ne t i c s ( 1 8 - 2 2 ) . Re s u l t s o f a c ryomi c ro s copy exp e r iment (la) , i n whi ch the i n c r e a s e i n i c e c ry s t a l d i ame t e r wa s me a s ur e d as a f un c t i o n of Tg ' f o r a s e r i e s o f mo d e l s ug a r/ma l t o dext r i n s o lut i o n s ( T g ' r a n g e - 9 . 5 t o -3 1 ° C ) a f t e r 4 we e k s o f s t o ra g e in a - 1 8 ° C home f r e e z e r , i l l u s t ra t e d t h i s dynam i c b ehavi o r and the c ryo s t a b i l i z i ng ( i . e . T g ' - e l eva t i ng ) e f f e c t o f a h i g h MW SHP (�) . When Tf wa s b e l ow Tg ' ( - 1 8 < - 9 . 5 ° C ) , t h e i c e c ry s t a l s i z e r ema ined n e a r l y the s ame a s f o r t h e i ni t i a l l y f ro z en s amp l e s . When Tf wa s a b ove Tg ' , the i n c r e a s e i n i c e c ry s t a l s i z e ( i . e . d e c r e a s ing s t a b i l i ty ) d emon s t ra t e d a s t r i k i ng c o r r e l a t i on w i t h d e c r e a s i ng Tg ' ( thus , inc r e a s ing A T ) , and t h e t emp e ra t u r e d e p e n ­ d e n c e wa s c l e a r ly g r e a t e r t h a n that exp e c t e d f o r Ar r h e n i u s k i n e t i c s . Fo r t h e c ryo s t a b i l iz a t i o n o f r e a l f ro z en f o o d p ro d uc t s s uc h a s i c e c r e am ( w i t h d e s i ra b l e smoo t h , c r eamy t ex t ur e ) a g a i n s t i c e c ry s t a l g rowth ove r s t o ra g e t ime ( a t T f > Tg ' ) , i n c lus i o n o f po l yme r i c c ryo ­ s t a b i l i z e r s s uc h a s l ow DE ma l t o d ext r i ns e l eva t e s the c omp o s i t e Tg ' o f a m i x o f s o l ub l e s o l i d s tha t i s typ i c a l l y domina t e d by l o w MW s ug ­ In p r a c t i c e , a r e t a rd e d r a t e o f m i g r a t o ry i c e r e c ry s t a l ­ a r s (�) . l i z a t i on ( " g r a i n g rowt h " o f p r e - exi s t ing i c e c rys t a l s ) ( 4 7 ) a t T f and a n i nc r e a s e i n o b s e rv e d T r r e su l t . Such b ehav i o r h a s b e e n d o c ume n t e d i n s ev e r a l " s o f t - s e rve " i c e c ream p a t ent s ( 2 7 . 2 8 . 1 1 1 ) . I n s uch p ro d ­ u c t s ( and i n a va r i e t y o f o t h e r f ro z en f o o d s and a q u e o u s mo d e l s y s ­ t ems ) , i c e r e c ry s t a l l i z a t i o n ha s b e e n s hown t o i nvo lve a d i f f u s i o n ­ l imi t e d ma tur a t i on p ro c e s s wi th a me chan i sm ana l o g o u s t o " O s twa l d r i p e n i ng " , whe r e by l a r g e r c rys t a l s g row w i t h t ime a t t h e exp e n s e o f s ma l l e r o n e s wh i ch eventua l l y d i s ap p e a r ( 1 8 . 2 0 , 2 2 and r e f s . t h e r e i n ) . The r i p ening ra t e a t If i s r e duc e d ( due to re duc e d AT a b ove T g ' ) by f o rmu l a t i o n w i t h low DE ma l t o d ext r i n s o f h i g h Tg ' ( � ) . Low DE ma l t o dext r i n s have a l s o b e en us e d t o s t a b i l i z e f ro z e n d a i ry p ro duc t s a g a i n s t l a c t o s e c rys t a l l i z a t i on dur i ng s t o ra g e ( 1 1 2 ) , a no the r c o l ­ l ap s e p r o c e s s ( s e e Tab l e I) wh i ch can o c c ur i n a p r a c t i c a l t ime f rame at T f > Tg ' . I n f a c t , a s indi c a t e d by t h e f o o t no t e t o Tab l e I ( � 2 6 ) , h i gh - p o l yme r i c S H P s have b e en us e d a s e f f e c t ive s t a b i l i z e r s a g a i n s t c o l l ap s e i n the ma j o r i ty o f the l i s t e d c o l l a p s e p r o c e s s e s . As no t e d e a r l i e r , whe th e r f o r c ryo s t a b i l i z a t i o n , e n c ap s u l a t i o n , the rmo ­ me chani c a l s t a b i l i z a t i o n , o r f a c i l i t a t i o n o f d ryi n g p r o c e s s e s , t h e u t i l i t y o f s uch S H P s d e rive s f rom the s t ru c t u r e - func t i o n r e l a t i on s h i p d e f i n e d by the e n t ang l ement p l a t eau r e g i o n i n F i gure 6 . The c ryo s t a b i l i z i ng func t i ona l i t y o f s a c c ha r i d e p o l yme r s ha s a l s o b e e n d emons t ra t e d by D S C me a s urement s o f T g ' va l u e s f o r va r i o u s d i a g no s t i c t h r e e - c omponent a q u e o u s s o l ut i o n s a s mo d e l s ys t em s f o r f ro z e n f o o d s ( 1 8 . 2 0 . 2 2 ) . The s e r e s u l t s i l l u s t ra t e d v e ry c l ea r l y t h e d e p e n d e n c e o f Tg ' on the we i ght - ave r a g e c omp o s i t i o n o f a c ompa t i b l e , mu l t i - s o l ut e mixture ( 1 ) . In thi s cont ext , an i nt e r e s t ing i l l us t ra ­ t i o n o f wha t ha s b e e n g l e a n e d f rom an ana l ys i s o f g l a s s c urve s f o r s uc h c o mp l ex aqueous mixtur e s i s s hown i n F i g u r e 1 3 ( 1 ) . In thi s =

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1 00% Sol ute 1 0% Solute 2 0% Plasticize r 3

0% Sol ute 1 1 00% Solute 2 0% Plasticize r 3 T92

0% Sol ute 1 0% Sol ute 2 1 00% P lasticizer 3

� �?-"!:J�tt==t:-::r7i

Figure 13. A schematic 3-dimensional state diagram for a hypothetical 3component aqueous system. The two solutes (e.g. polymer + monomer) are both non-crystallizing, interacting, and plasticized by water, which is the crystallizing solvent. The diagram illustrates the postulated origin of a sigmoidal curve of Tg' vs. w% solute composition. (Reproduced with permission from reference 3. Copyright 1988 Cambridge University Press.)

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a r t i s t ' s r e n d e ring o f a thr e e - d imens i o na l s t a t e d i a g ram f o r a hyp o ­ t he t i c a l t h re e - c omp onent s y s t em , b o t h s o l ut e s ( e . g . a p o l yme r , 2 , and i t s monome r , 1 ) are non - c ry s t a l l i z i ng , i nt e ra c t i ng ( i . e . c omp a t i b l e ) , and p l a s t i c i z e d by wa t e r , wh i c h i s t h e c ry s t a l l i z ing s o lvent , 3 . The d i a g ram reve a l e d the p o s t u l a t e d o r i g in of a s i gmo i d a l Tg ' ( c ) curve , i . e . t h e T g ' g l a s s curve ABCDEF ( 1 ) . In f a c t , s im i l a r s i gmo i d a l c u rve s o f T c v s . w% concent ra t i on , f o r c o l l ap s e during f re e z e - d rying o f ana l o g o u s t h re e - c omponent aqueous s ys t ems , h a d p r ev i o u s l y b e en r e ­ p o r t e d ( F i g u r e 5 i n MacKenz i e ( 34 » , but " th e b a s i s f o r [ th e i r no n ­ Four s e r i e s o f mo d e l l in e a r i t y ) ha [ d ) no t b e e n d e t e rmine d " ( 3 4 ) . s o l ut i on s a t 1 0 w% t o t a l s o l i d s c ompo s e d o f mixt u r e s wi t h va r y i n g r a t i o s o f ma l t o d ext r i n s ( 0 . 5 - 1 5 DE ) t o f ruc t o s e d emon s t ra t e d a n e x ­ p e r iment a l ve r i f i c a t i o n o f the p o s t ul a t e d s i gmo i da l shap e o f Tg ' ( c ) c u rv e s , a s s hown by the p l o t s o f Tg ' v s . w% ma l t o d ex t r i n i n F i gu r e 1 4 (�) . I t ha s b e en f o und tha t such s i gmo i da l g l a s s c u rv e s r e p r e s e n t t h e g e ne r a l behav i o r o f c ompa t i b l e mixture s o f b o t h homo l o g ou s a n d non - homo l o g o u s p o l yme r i c ( inc l ud i ng Na c a s e ina t e p ro t e i n ) a n d l o w MW ( i n c l ud i ng va r i ous s ug a r s and a c i d s ) s o l ut e s ( � ) . I n a l l s uc h c urv e s , t h e l o w - a n d h i gh - Tg ' t i e p o i n t s we r e d e t e rm i n e d b y t h e T g ' va l ue s o f the i n d i v i dua l l ow and h i gh MW s o l ut e s , r e s p e c t i ve l y . Fig­ u r e 1 4 i l l u s t ra t e d th a t the c omp o s i t e Tg ' va lue cha ra c t e r i s t i c o f a g iven amo rphous s o l u t e ( s ) - UFW compo s i t i on i s gove rne d by t h e Mw o f t h e p a r t i cu l a r c omb i na t i on o f c ompa t i b l e wa t e r - s o l ub l e s o l i d s i n a c omp l ex f r o z en s y s t em .. I t h a s a l s o b e en u s e d t o i l lu s t r a t e t h e p r i n ­ c i p l e o f p o l yme r i c c ryo s t a b i l i z a t i o n : t h e s t a b i l i z i ng inf l ue n c e o n t h e s t ru c t ura l s t a t e o f a c omp l ex amo rphous ma t r i x d e r ive s f rom t h e h i g h MW o f p o l yme r i c c ryo s t a b i l i z e r s a n d the r e s u l t ing e l eva t i ng e f ­ f e c t o n Tg ' o f a f o o d p roduct (�) . S a c cha r i d e Po lyme r s a s C o l lap s e I nhi b i t o r s i n Low Mo i s t u r e Sys t ems . As exp l a i n e d e l s ewhe r e ( 2 3 ) , i f the re l a t i v e shap e s o f t h e p o l yme r ­ d i luent g l a s s curve s a r e s imi l a r w i t h i n a homo l o gous p o l yme r s e r i e s , i n c r e a s e s in MW ( o f the d i l uent - f r e e po lyme r ) l e a d t o p ro p o r t i ona l i n c r e a s e s i n b o t h Tg and Tg ' . Thi s f a c t ha s b e e n r e c e n t l y d emons t r a ­ t e d b y the a q u e o u s g l a s s curve s f o r ma l t o s e , ma l t o t r i o s e , and ma l t o ­ hexao s e p ub l i s h e d b y O r f p r d e t a l . ( 1 1 3 ) , c o up l e d wi t h Tg ' - Wg ' va lue s f o r t he s e o l i g o s a c cha r i d e s ( l ) . P r i o r t o t h i s co n f i rma t i o n , i t h a d b e e n a s s ume d th at a p l o t o f Tg vs . MW f o r d ry PHC s o r S H P s wo u l d r e ­ f l e c t the s ame fundame nt a l b ehavi o r a s tha t o f Tg ' v s . s o l u t e MW s hown i n F i gu r e s 6 , 7 , and 8 ( 2 6 ) . E a r l i e r ev i d e n c e s upp o r t i n g t h i s a s s ump t i o n h a d b e e n p rovi d e d by T o and F l ink ( 3 5 ) , who r ep o r t e d a p l o t o f T c V S . DP f o r a s e r i e s o f low mo i s t u r e , f ra c t i ona t e d S H P o l i ­ gome r s o f 2 s DP s 1 6 ( i . e . non - e n t ang l i ng ( 1 » , s imi l a r i n s ha p e t o t h e p l o t o f T g ' vs . MW f o r t h e non - en t a ng l i ng PHC s i n F i g u r e 7 . It h a d b e en p o int e d o u t t h a t T c f o r low mo i s t u r e SHP s , whi c h i nc r e a s e s mono t o n i c a l l y w i t h i n c r e a s ing DP , rep r e s ent s a g o o d quant i t a t ive a p ­ p roxima t i o n o f dry Tg ( 1 ) . The ba s i c a s s ump t i o n wa s ve r i f i e d f o r the homo l o g o u s s e r i e s o f g l uco s e and i t s pure ma l t o - o l i g ome r s of D P 2 - 7 ( 2 6 ) . A p l o t o f Tg vs . MW s howed t h a t d ry Tg i n c r e a s e s mono t o n i c a l ly w i t h inc r e a s ing MW o f the monod i s p e r s e s ug a r , f rom Tg 3 1 ° C f o r g lu ­ c o s e ( i n g o o d a g r e ement wi th s ever a l o t h e r p ub l i s h e d va l ue s ( l and re f s . the r e i n » t o Tg l 3 8 . S o C for ma l t ohe p t a o s e ( 2 6 ) . The p l o t s howed t h e s ame qua l i t a t ive c u rva ture ( a nd a b s e n c e o f a n e n t ang l ement p l a t e a u ) as the c o r r e s p ond ing T g ' p l o t i n F i gure 8 , and t h e p l o t of d ry Tg v s . l /MW s howed the s ame l i n e a r i t y and r va lue as t h e c o r r e =

=

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[ Th e s e r e s u l t s w e r e s p ond i ng Tg ' p l o t in the ins e t o f F i gu r e 8 ( 2 6 ) . s ub s equent l y c o r r o b o r a t e d b y O r f o rd e t a l . ( 1 1 3 ) , who r e c en t l y r e po r t ­ e d a s im i l a r c urve o f d ry Tg vs . DP f o r g l uc o s e and i t s ma l t o - o l i go ­ me r s o f DP 2 - 6 . ] Furt he r ve r i f i c a t i o n o f the a s s ump t i o n wa s d emon ­ s t ra t e d by a p l o t ( s hown in F i gure 1 5 ( 2 6 » o f T g v s . w% c ompo s i t i o n f o r a s e r i e s o f s p r a y - d r i e d , low mo i s t u r e powd e r s ( a bout 2 w% wat e r ) p r e p a r e d f rom s o lut i o n b l ends o f comme r c i a l SHP s , L o d ex 1 0 and Ma l ­ t r i n M3 6 5 . Thi s p l o t s howe d that Tg i n c r e a s e s f rom 5 8 ° C f o r Ma l t r i n M3 6 5 ( 3 6 DE , Tg ' -2 2 . S 0 C ) t o 1 2 1 ° C f o r Lodex 1 0 ( 1 1 DE , Tg ' - l l . S 0 C) f o r t h e s e S H P s a t about 2 w% mo i s ture . H e r e a g a i n , the cha ra c t e r i s ­ t i c mono t o n i c i nc r e a s e o f Tg w i t h Mw ( = i nc r e a s ing c ompo s i t i o n a s w% L o d ex 1 0 ) and c urva ture exp e c t e d and t he o r e t i c a l l y p r e d i c t e d f o r ho ­ mo l o g o u s ( m i x t ur e s o f ) o l i g ome r s w i t h MW va lue s b e l ow t h e e n t a ng l e ­ ment p l a t e a u l im i t we r e evident . As ment i o n e d e a r l i e r , the p r i n c i p l e s o f c ryo s t a b i l i z a t i o n t e ch ­ no l o g y have a l s o b e e n app l i e d s uc c e s s f u l ly t o t h e p r event i o n o f c o l ­ l ap s e p ro c e s s e s i n low mo i s t u r e , g l a s s - f o rming f o o d s y s t ems , t h rough t h e u s e o f s a c cha r i d e p o l yme r s a s s t a b i l i z i ng ing r e d i e nt s to r a i s e the c omp o s i t e Mw and r e s u l t ing Tg o f a mixture o f wa t e r - c ompa t i b l e s o l i d s , o the rwi s e typ i c a l ly domina t e d b y l ow MW , l ow T g c omp o n e n t s s uc h a s s ug a r s and a c i d s ( 2 6 ) . As i l lus t ra t e d i n F i g u r e 1 6 ( da t a f rom Fouad S a l e e b , G e n e ra l F o o d s C o rp . , p e r s ona l c ommun i c a t i o n , 1 9 84 . ) , t h e t h e rmome chan i c a l s t ab i l i z a t i o n o f amo rphou s f o o d p o wd e r s b y l ow DE S H P s h a s b e e n d emon s t ra t e d in mo d e l s y s t em s t ud i e s o f s p ray - d r i e d , t h r e e - c omp o n e n t mixture s . F i gure 1 6 s hows tha t t yp i c a l low MW g l a s s ­ f o rme r s ( e . g . c ommon f o o d i ng r e d i e n t s s uch a s ma l t o s e monohyd ra t e , manno s e , and c i t r i c a c i d ) , a t l ow mo i s t u r e cont ent s , o f t en have l ow Tg va l ue s , a ro und and even b e l ow room t emp e r a t u r e . Fo r t h i s r e a s on , s uc h amo rphous f o o d mat e r i a l s a r e p a r t i cu l a r l y s en s i t iv e t o mo i s t u r e up t a ke and p rone t o c o l l ap s e ( e . g . c a k i ng ) dur i ng amb i ent s h e l f s t o r ­ a g e . Howeve r , a s s hown i n F i gu r e 1 6 , i n mixed g l a s s e s c o n t a i n i n g a p o l yme r i c s t a b i l i z e r s uch a s 1 0 DE ma l t o dext r i n , the c ompo s i t e T g i n c r e a s e s d rama t i c a l ly w i t h i n c r e a s ing w % s t abi l i z e r , d u e t o i n c r e a s ­ i n g Mw . Thus , i n g ene ra l , 1 0 DE ma l t o d ext r i n i s an exc e l l e n t t h e rmo ­ m e chan i c a l s t a b i l i z e r , wh i ch i s c apab l e o f e l eva t i ng t h e Tg o f a n amo rphous m i x t u r e t o a " s a f e " t emp e r a t u r e we l l a b o v e r o o m t emp e r a ­ t u r e , and t h e r e by inhi b i t ing co ll ap s e p r o c e s s e s d u r i n g amb i en t s t o r ­ a g e and i n c r e a s ing p roduct s he l f - l i f e . =

=

C o n c l u s i on In t h i s chap t e r , we have r evi ewed the deve l opment and h i gh l i g h t e d s ome t e chno l o g i c a l app l i c a t i o n s o f a p o lyme r cha ra c t e r i z a t i o n me t ho d , b a s e d on l ow t emp e r a t ur e D S C and d e r ived f rom a f o o d p o l ym e r s c i e n c e r e s e a r ch a p p r o a c h , t o ana lyz e t h e s t ru c t ur e - phys i co chemi c a l p r o p e r t y r e l a t i o n s h i p s o f l i ne a r , b ranche d , and cyc l i c mono - , o l i go - , a n d p o l y ­ s a c c ha r i d e s . Through the us e o f t h i s D S C c h a r a c t e r i z a t i o n m e t ho d , imp o r t a n t s ub t l e t i e s o f the s t ru c t u r e - p ro p e r t y r e l a t i o n s h i p s o f S H P s and PHC s have b e e n revea l e d . O u r D S C r e s u l t s h a v e empha s i z e d t h e un ­ avo i d a b l e c o n c lus i o n , conc e rning the cho i c e o f a s u i t a b l e s a c cha r i d e i ng r e d i ent f o r a s p e c i f i c f o o d app l i c a t i on , t h a t o n e S H P ( o r PHC ) i s no t ne c e s s a r i ly i nt e r c hang e a b l e w i t h ano the r o f the s ame nomi n a l DE ( o r MW ) . We have s hown that cha ra c t e r i z a t i o n of f undame nt a l s t ru c ­ t u r e - p ro p e r t y r e l a t i on s h i p s , in t e rms o f Tg ' , i s h i g h l y a dv i s ab l e b e f o r e s e l e c t i o n o f such i ng r e d i e n t s f o r us e i n f a b r i c a t e d f o o d p ro d -

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8

-

T / 3

°c

18

-28

-38 0 •

-48

0 •

- 58

8

1

2

3

4

5

We i ght

G �

7

B

9

8 . 5 DE 5 DE 18 DE 15 DE 18

na l todextr i n

Figure 14. Variation of the glass transition temperature, Tg', for maximally frozen solutions against weight % maltodextrin in 10 w% total solids solutions of maltodextrin + fructose, for four different low DE maltodextrins. (Reproduced with permission from reference 18. Copyright 1988 Cambridge.) 1381.------, 128

1 18 188

98

88 78

68

58

8

18

28

38

48

Co�pos i t i on

58 as

68

78

wX Lodex

88

18

98 188

Figure 15. Variation of the glass transition temperature, Tg, against weight % composition for spray-dried, low moisture powders prepared from aqueous solution blends of Lodex 10 (10 DE maltodextrin) and Maltrin M365 (36 DE corn syrup solids) SHPs. (Reproduced with permission from reference 26. Copyright 1989 Elsevier.)

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1 20 1 00

Tg

80

°C

60

MALTOSEH2O 40

MANNOSE

20

CITR I C ACID

0

40

20

60

1 00

80

COM POS I T I O N WE I G HT % LO DEX 1 0 Figure

.1 6 .

Va r i a t i o n o f

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256

BIOTECHNOLOGY OF AMYLODEXTRIN OLIGO SACCHARIDES

u c t s . The s tud i e s revi ewe d in t h i s chap t e r have a l s o s e rv e d t o d em ­ ons t ra t e t h e maj o r oppo r t un i ty o f f e r e d by the f o o d p o lyme r s c i en c e a p p r o a c h t o expand no t only o u r quant i t a t ive knowl e d g e b u t a l s o , o f b ro a d e r p ra c t i c a l va lue , o u r qua l i t a t ive und e r s t anding o f , a n d a b i l i ­ t y t o c o r r e c t ly p r e d i c t , the s t ruc t ur e - f un c t i o n r e l a t i o n s h i p s o f l in ­ e a r , b ra n c he d , and cyc l i c mono - , o l i g o - , and p o ly s a c cha r i d e s i n a w i d e va r i e t y o f f o o d p ro duc t s and p ro c e s s e s .

L i t e ra t u r e C i t e d 1. 2.

3.

4.

5.

6. 7. 8. 9. 10. 11. 12. 13 . 14 . 15.

16 . 17.

18. 19. 20 .

Levine , H . ; S l a d e , L . C a rbohyd r . Po 1ym . 1 9 8 6 , Q , 2 1 3 - 4 4 . L e v i n e , H . ; S l a d e , L . I n F o o d S t ru c t u r e - I t s C re a t i o n a n d Eva l ­ ua t i on ; Mi t che l l , J . R . ; B l an s ha rd , J . M . V . , E d s . ; But t e rwo r t h s : Londo n , 1 9 8 8 ; pp 1 4 9 - 8 0 . L e v i ne , H . ; S l a d e , L . In Wa t e r S c i en c e Rev i ew s ; F r an k s , F . , E d . ; Camb r i dg e Un ive r s i t y P r e s s : C amb r i d g e , 1 9 8 8 ; Vo l . 3 , pp 7 9 - 1 85 . S l a d e , L . ; Levine , H . ; F i n l e y , J . W . ; I n P ro t e i n Qua l i ty and the E f f e c t s o f P r o c e s s in� ; Phi l l i p s , D . ; F i n l ey , J . W . , E d s . ; Ma r c e l D e kke r : New Y o r k , 1 9 8 9 ; p p 9 - 1 24 . L e v i n e , H . ; S l a d e , L . In Dough Rheo l o gy and B a k e d P ro du c t Tex ­ t u r e ; Fa r i d i , H . ; Faub i on , J . M . , E d s . ; Van No s t rand Re i nh o l d! AVI : New Yo rk , 1 9 8 9 ; pp 1 5 7 - 3 3 0 . S l a d e , L . ; Levine , H . CRC C r i t . Revs . F o o d S c i . Nut r . 1 9 9 0 , i n pres s . S l a d e , L . ; Levine , H . ; In Wa t e r Re l a t i on s h i p s I n F o o d s ; L e v i n e , H . ; S l a d e , L . , E d s . ; P l enum : New Yo rk , 1 9 9 1 ; pp 2 9 - 1 0 1 . F l o ry , P . J . P r inc ip l e s o f Po lyme r Chemi s t ry ; C o rne l l Uni ve r s i t y P r e s s : I tha c a , 1 9 5 3 . Wunde r l i ch , B . In The rma l Cha ra c t e r i z a t i o n - o f P o lyme r i c Ma t e r i ­ a l s ; Tur i , E . A . , E d . ; Ac a d em i c P r e s s : O r l ando , 1 9 8 1 ; pp 9 1 - 2 3 4 . F e r ry , J . D . Vi s co e l a s t i c P rope r t i e s o f Po lyme r s , 3 rd e dn . ; J ohn W i l ey & S o n s : New Yo r k , 1 9 80 . S e a r s , J . K . ; Da rby , J . R . The Te chno l o �y o f P l a s t i c i z e r s ; Wi l ey ­ I n t e r s c i en c e : New Yo rk , 1 9 8 2 . B i l lmeye r , F . W . Text b o o k o f Po lyme r S c i e n c e , 3 rd e d n . ; Wi l ey ­ I nt e r s c i e nc e : New Yo rk , 1 9 84 . S p e r l i ng , L . H . Int roduc t i on t o Phys i c a l Po lyme r S c i e n c e ; W i l e y ­ I nt e r s c i en c e : New Yo rk , 1 9 8 6 . S l a d e , L . ; Levine , H . C a rbohyd r . Po lym . 1 9 8 8 , � , 1 8 3 - 2 0 8 . S l a d e , L . ; Levine , H . In Indus t r i a l Po lys a c cha r i d e s - The I m ­ pa c t o f B i o t e chno 1 o �y and Adva n c e d Methodo l o g i e s ; S t iva l a , S . S . ; C r e s c e nz i , V . ; D e a , I . C . M . , E d s . ; Go rdon and B r e a c h S c i ­ e n c e : New Yo rk , 1 9 8 7 ; pp 3 8 7 - 4 3 0 . S l a d e , L . ; Levine , H . In CRA S c i ent i f i c C o n f e r e nc e ; C o rn Re f i n ­ e r s As s o c . : Wa s h i ng t on , DC , 1 9 8 8 ; p p 1 6 9 - 2 4 4 . S l a d e , L . ; Levine , H . In Front i e r s in C a r b ohyd r a t e Re s e a r c h - I : F o o d App l i c a t i ons ; Mi l 1 ane , R . P . ; BeMi l l e r , J . N . ; C ha n d r a s e ka r ­ an , R . , E d s . ; E l s ev i e r App l i e d S c i en c e : Londo n , 1 9 8 9 ; p p 2 1 5 70 . L e v i n e , H . ; S l a d e , L . C ryo - L e t t . 1 9 8 8 , 2 , 2 1 - 6 3 . Levine , H . ; S l a d e , L . J . Chem . S o c . , Fa raday T r a n s . I 1 9 8 8 , 8 4 , 261 9 -33 . L e v i n e , H . ; S l a d e , L . C omment s Ag r i c . F o o d Chem . 1 9 8 9 , 1 . 3 1 5 - 9 6 .

16.

21 . 22 .

23 . 24 .

25 .

26 . 27 . 28 . �9 . 30 . 31 . 32 . 33 . 34 .

35. 36 . 37 .

38 . 39. 40 . 41 . 42 . 43 . 44 . 45 .

46 . 47 . 48 . 49 .

LEVINE & SLADE

Characterization of Oligosaccharides

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L e v i n e , H . ; S l a d e , L . C ryo - L e t t . 1 9 8 9 , lQ , 3 4 7 - 7 0 . L e v i n e , H . ; S l a d e , L . I n The rma l Ana lys i s o f Fo o d s ; Ma , C . - Y . ; H a rwa l ka r , V . R . , E d s . ; E l s evi e r App l i e d S c i en c e : London , 1 9 9 0 ; chapt e r 9 . S l a d e , L . ; Levine , H . Pure App l Chern . 1 9 8 8 , QQ , 1 84 1 - 64 . S l a d e , L . ; Levine , H . I n Advan c e s i n Me a t R e s e a r c h . Vo l . 4 C o l l a g e n a s a F o o d ; P e a r s on , A . M . ; Dut s on , T . R . ; B a i l e y , A . , E d s . ; AVI : We s t p o r t , 1 9 8 7 ; pp 2 5 1 - 6 6 . S l a d e , L . ; Levine , H . In F o o d S t ruc t u r e - I t s C re a t i o n a n d Eva l ­ ua t i o n ; Mi t che l l , J . R . ; B l an s ha r d , J . M . V . , E d s . ; But t e rwo r t h s : London , 1 9 8 8 ; pp 1 1 5 - 4 7 . L e v i n e , H . ; S l a d e , L . In Wa t e r and F o o d Qua l i ty ; H a rdman , T . M . , E d . ; E l s ev i e r : London , 1 9 8 9 ; pp 7 1 - 1 34 . C o l e , B . A . ; Levine , H . I . ; McGui r e , M . T . ; Ne l s on , K . J . ; S l a d e , L . U . S . P a t ent 4 3 7 4 1 5 4 , 19 8 3 . C o l e , B . A . ; Levine , H . I . ; McGui r e , M . T . ; Ne l s on , K . J . ; S l a d e , L . U . S . P a t ent 4 4 5 2 8 24 , 1 9 84 . S l a d e , L . ; A l t oma r e , R . ; O l t z i k , R . ; Me d c a l f , D . G . U . S . P a t e n t 4 657 770 , 1 987 . ' B e Mi l l e r , J . N . ( a s r ep o r t e d by H i l l , M . A . ) C a r b o hyd r . P o l ym . 1 9 8 9 , lQ , 6 4 . F ranks , F . ; ,As qui th , M . H . ; Hammond , C . C . ; S ka e r , H . B . ; E c h l i n , P . J . Mi c ro s c . 1 9 7 7 , 1 1 0 , 2 2 3 - 3 8 . Ma cKenz i e , A . P . Ph i l . Trans . Roya l S o c . London B . 1 9 7 7 , 2 7 8 , 1 6 7 - 89 . Ka r e l , M . In P rope r t i e s o f Wa t e r i n Fo o d s ; S ima t o s , D . ; Mul t o n , J . L . , E d s . ; Ma r t i nus N i j ho f f : Do r d r e cht , 1 9 8 5 ; pp 1 5 3 - 6 9 . MacKenz i e , A . P . In F r e e z e D ry ing and Adva n c e d F o o d Te chno l o gy ; Go l d l i th , S . A . ; Rey , L . ; Rot hm ay r , W . W . , E d s . ; A c a d em i c P r e s s : New Yo r k , 1 9 7 5 ; p p 2 7 7 - 3 0 7 . To , E . C . ; F l ink , J . M . J . F o o d Te chno ! . 1 9 7 8 , ll , 5 5 1 - 94 . F l i nk , J . M . I n Phys �'ca l P rope r t i e s o f F o o d s : P e l e g , M . ; B a g l ey , E . B . , E d s . ; AVI : We s tp o r t , 1 9 8 3 ; pp 4 7 3 - 5 2 1 . Ka r e l , M . ; F l ink , J . M . I n Advanc e s in D ry i ng ; Muj umda r , A . S . , E d . ; Hemi s phe r e : Wa s h i n g t o n , 1 9 8 3 ; Vo l . 2 , pp 1 03 - 5 3 . F r anks , F . In Wa t e r : A Comprehe n s ive T r e a t i s e ; . F r a n k s F . , E d . ; P l enum P r e s s : New Yo rk , 1 9 8 2 ; Vo l . 7 , p p 2 1 5 - 3 3 8 . F r a nk s , F . B i ophy s i c s and B i o che m i s t ry a t Low Temp e r a t u r e s ; C a mb r i d g e Unive r s i t y P r e s s : C amb r i d g e , 1 9 8 5 . F ranks , F . In P rope r t i e s o f Wa t e r i n F o o d s : S ima t o s , D . ; Mul t o n , J . L . , E d s . ; Ma r t i nus N i j ho f f : D o r d r e cht , 1 9 8 5 ; p p 4 9 7 - 5 0 9 . F ranks , F . J . Mi c ro s c . 1 9 8 6 , 1 4 1 , 2 4 3 - 4 9 . F r anks , F . P ro c e s s B i'o chem . 1 9 8 9 , lilli , R3 - R7 . Ma r s h , R . D . L . ; B l a n s ha rd , J . M . V . C a r b o hyd r . Po lym . 1 9 8 8 , 2 , 301 - 17 . S o e s an t o , T . ; Wi l l i ams , M . C . J . Phys . Chern . 1 9 8 1 , 8 5 , 3 3 3 8 - 4 1 . S t a rkwe a t h e r , H . W . I n Wa t e r in Po lyme r s ; Row l an d , S . P . , E d . ; AC S S ymp . S e r . 1 2 7 ; Ame r i c an Chemi c a l S o c i e t y , Wa s hi n g t o n , D C , 1 9 8 0 ; pp 4 3 3 - 4 0 . H o f e r , K . ; Ha l l b ru c ke r , A . ; Maye r , E . ; J o ha r i , G . P . J . Phys . C h ern . 1 9 8 9 , 9 3 , 4 6 7 4 - 7 7 . Luye t , B . Ann , NY A c a d . S c i . 1 9 6 0 , 8 5 , 5 4 9 - 6 9 . Ra smus s en , D . ; Luye t , B . B i o dynam i c a 1 9 69 , lQ , 3 1 9 - 3 1 . MacKenz i e , A . P . ; Ra smus s en , D . H . In Wa t e r S t ru c t u r e a t t h e Wa .

,

258

50 . 51 . 52 . 53 . 54 . 55 .

56 .

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t e r - Po lyme r I nt e r f a c e ; J e l 1 i nek , H . H . G . , E d . ; P l e num P re s s : New Yo rk , 1 9 7 2 ; pp 1 4 6 - 7 1 . Va s s o i 1 1 e , R . ; E 1 H a c h a d i , A . ; Vi g i e r , G . C ryo - L e t t . 1 9 86 , I , 305 - 10 . Ma c F a r l ane , D . R . C ryo - L e t t . 1 9 8 5 , Q , 3 1 3 - 1 8 . Bout ron , P . ; Kaufmann , A . C ryo b i o l . 1 9 7 9 , lQ , 5 5 7 - 6 8 . B o h o n , R . L . ; C onway , W . T . The rmo c h im . A c t a 1 9 7 2 , � , 3 2 1 - 4 1 . V r e n t a s , J . S . ; Hou , A . C . J . App l . P o 1ym . S c i . 1 9 8 8 , 3 6 , 1 9 3 3 34 . Maye r , E . C ryo - Le t t . 1 9 8 8 , 2 , 6 6 - 7 7 . Fahy , G . M . ; L evy , . D . I . ; Al i , S . E . C ryob i o l . 1 9 8 7 , 24 , 1 9 6 2 13 .

57 .

58 . 59 .

60 .

61 . 62 . 63 . 64 .

65 .

66 .

67 .

68 .

69 . 70 . 71 . 72 . 73 . 74 . 75 .

76 .

77 . 78 .

.

G r a e s s l e y , W . W . In Phys i c a l P rope r t i e s o f Po lyme r s ; Ma rk , J . E . ; E i s en b e rg , A . ; G r a e s s l e y , W . W . ; Mand e lke rn , L . ; Ko e ni g , J . L . , E d s . ; Ame r i c a n Chemi c a l S o c i e t y , Wa s h i ng t o n , DC , 1 9 84 ; pp 9 7 1 53 . B ryd s o n , J . A . In Po lyme r S c i en c e ; J e nk i n s , A . D . , E d . ; No r t h H o l l and , Ams t e r dam , 1 9 7 2 ; pp 1 9 4 - 2 4 9 . S h a l a b y , S . W . In The rma l Cha ra c t e r i z a t i o n o f P o lyme r i c Ma t e r i ­ a l s ; Tur i , E . A . , E d . ; Ac a d emi c P r e s s , O r l ando , 1 9 8 1 ; pp 2 3 5 3 64 . D z i e d z i c , S . Z . ; Ke a r s 1 e y , M . W . In G l uco s e · Syrup s : S c i en c e and T e chno l o �y ; D z i e d z i c , S . Z . ; Ke a r s 1 ey , M . W . , E d s . ; E l s ev i e r Ap ­ p l i e d S c i en c e , London , 1 9 84 , pp 1 3 7 - 6 8 . B ro o k s , J . R . ; G r i f f i n , V . K . C e re a l Chern . 1 9 8 7 , 6 4 , 2 5 3 - 5 5 . F l o ry , P . J . Fa r a d ay D i s c . Chern . S o c . . 1 9 7 4 , 5 7 , 7 - 1 8 . R i c ht e r , M . ; S ch i e rbaum , F . ; Augus t a t , S . ; Kno ch , K . D . U . S . P a t ent 3 9 6 2 4 6 5 , 1 9 7 6 . R i ch t e r , M . ; S ch i e rb aum , F . ; Augus t a t , S . ; Kno ch , K . D . U . S . P a t en t 3 9 8 6 8 9 0 , 1 9 7 6 . B raudo , E . E . ; B e l av t s eva , E . M . ; T i t ova , E . F . ; P l a s hc h i n a , I . G . ; K r y l o v , V . L . ; To l s t o guzov , V . B . ; S c h i e r baum , F . R . ; R i cht e r , M . S t arke 1 9 7 9 , 11, 1 8 8 - 9 4 . B raudo , E . E . ; P l a shchina , I . G . ; To 1 s t o guzov , V . B . C a r b o hyd r . Po lym . 1 9 84 , � , 2 3 - 4 8 . B u l p i n , P . V . ; C ut l e r , A . N . ; D e a , ' I . C . M . I n Gums and S t a b i l i z e r s' f o r the F o o d Indus t ry 2 ; Phi l l i p s , G . O . ; Wed l o c k , D . J . ; W i l I i ams , P . A . , E d s . , P e rgamon P r e s s , Oxf o r d , 1 9 8 4 ; pp 4 7 5 - 84 . Reuthe r , F . ; Dama s chun , G . ; G e r n a t , C . ; S ch i e r b a um , F . ; K e t t ­ l i t z , B . ; Rado s t a , S . ; No thnag e l , A . C o l I . Po lym . S c i . 1 9 84 , 2 6 2 , 643 - 4 7 . L e n ch i n , J . M . ; T rub i ano , P . C . ; H o f fman , S . U . S . P a t e n t 4 5 1 0 1 66 , 1 985 . Mi l e s , M . J . ; Mo r r i s , V . J . . ; Ring , S . G . C a r b o hyd r . R e s . 1 9 8 5 , 135 , 257 -69 . E l l i s , H . S . ; Ring , S . G . C a rbohyd r . P o l ym . 1 9 8 5 , 2 , 2 0 1 - 1 3 . G e rman , M . L . ; B l umenf e l d , A . L . ; Yuryev , V . P . ; To l s t o gu z o v , V . B . C a rb ohyd r . Po lym . 1 9 8 9 , 11 , 1 3 9 - 4 6 . F e r ry , J . D . J . Ame r . Chern . S o c . 1 94 8 , 7 0 , 2 2 4 4 - 4 9 . M i t c h e l l , J . R . J . Text . S t ud . 1 9 8 0 , 11 , 3 1 5 - 3 7 . F ranks , F . Pure App l . C h ern . 1 9 8 7 , 5 9 , 1 1 8 9 - 2 0 2 . Z o b e l , H . F . S t a rke 1 9 8 8 , 4 0 , 1 - 7 . Rus s e l l , P . L . J . C e re a l S c i . 1 9 8 7 , Q , 1 4 7 - 5 8 . Me s t r e s , C . ; C o l onna , P . ; B u l eon , A . J . C e r e a l S c i . 1 9 8 8 , I , 1 23 -34 .

16. 79 . 80 . 81 .

82 .

83 . 84 . 85 . 86 . 87 . S8 . 89 . 90 .

91 .

92 . 93 . 94 . 95 . 96 . 97 . 98 . 99 . 1 00 . 101 . 102 . 1 03 . 1 04 . 1 05 . 1 06 . 1 07 .

108 . 1 09 . 1 10 .

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Characterization of Oligosaccharides

259

M i l e s , M . J . ; Mo r r i s , V . J . ; O r f o r d , P . D . ; R i n g , S . G . C a rb o hyd r . Res . 1 985 , 1 3 5 , 27 1 - 8 1 . Ma t suku r a , U . ; Ma t s una g a , A . ; Ka inuma , K . J . J p n S o c . S t a r c h S c i . 1 9 83 , 3 0 , 1 06 - 1 3 . R i n g , S . G . ; C o l o nna , P . ; l ' Ans on , K . J . ; Ka l i chev s ky , M . T . ; Mi l e s , M . J . ; Mo r r i s , V . J . ; O r f o rd , P . D . C a r b o hyd r . R e s . 1 9 8 7 , 1 6 2 , 277 - 93 . R i n g , S . G . ; O rf o rd , P . D . In Gums and S t a b i l i z e r s f o r t h e F o o d Indus t ry 3 ; Phi l l i p s , G . O . ; We d l o c k , D . J . ; Wi l l i ams , P . A . , E d s . , E l s evi e r App l i e d S c i en c e , London , 1 9 8 6 ; pp 1 5 9 - 6 5 . We l s h , E . J . ; Ba i l ey , J . ; Chanda rana , R . ; No r r i s , W . E . P ro g . F d . Nut r . S c i . 1 9 8 2 , Q , 4 5 - 5 3 . G i d l e y , M . J . Ma c romo l e cu l e s 1 9 8 9 , 2 2 , 3 5 1 - 5 8 . S t e eneken , P . A . M . C a rbohyd r . P o l yrn . 1 9 8 9 , 11 , 2 3 - 4 2 . G i d l e y , M . J . ; B u l p i n , P . V . Ma c romo l e c u l e s 1 9 8 9 , 2 2 , 3 4 1 - 4 6 . C l a rk , A . H . ; G i d l ey , M . J . ; R i c ha rd s op , R . K . ; Ro s s - Murphy , S . B . Ma c romo l e cu l e s 1 9 8 9 , 11 , 3 4 6 - 5 1 . R i n g , S . G . S t a rke 1 9 8 5 , Jl , 80 - 8 3 . l ' An s o n , K . J . ; Mi l e s , M . J . ; Mo r r i s , V . J . ; Ring , S . G . ; Nave , C . C a r b o hyd r . Po l yrn . 1 9 8 8 , � , 4 5 - 5 3 . G i d l e y , M . J . ; Bul p i n , P . V . ; Kay , S . In Gums and S t a b i l i z e r s f o r t h e F o o d Indus t ry 3 ; Ph i l l i p s , G . O . ; We d l o c k , D . J . ; Wi l l i am s , P . A . , E d s . , E l s ev i e r App l i e d S c i en c e , London , 1 9 8 6 ; p p 1 6 7 - 7 6 . Wh i s t l e r , R . L . ; Dan i e l , J . R . In S t a r c h : Chemi s t ry and T e c hno l o ­ gx ; Wh i s t l e r , R . L . ; BeMi l l e r , J . N . ; Pa s cha l l , E . F . , E d s . ; A c a ­ d emi c P r e s s , O r l ando , 1 9 84 ; 2nd e dn . , pp 1 5 3 - 8 2 . J a nkows ki , T . ; Rha , C . K . S t a r ke 1 9 8 6 , 3 8 , 6 - 9 . Bu l e on , A . ; Dup r a t , F . ; Booy , F . P . ; Chanzy , H . C a rb o hyd r . P o lyrn . 1 9 84 , !±. , 1 6 1 - 7 3 . H i z ukur i , S . C a rbohyd r . R e s . 1 9 8 6 , 1 4 7 , 3 4 2 - 4 7 . Atwe l l , W . A . ; H o o d , L . F . ; L i n e b a c k , D . R . ; Va r r i ano - Ma r s t on , E . ; Z o b e l , H . F . C e r ea l Foo d s Wo r l d 1 9 8 8 , 3 3 , 3 0 6 - 1 1 . R in g , S . G . Int . J . B i o I . Ma c romo l . 1 9 8 5 , I , 2 5 3 - 5 4 . Boye r , R . F . ; Ba e r , E . ; H i l tne r , A . Ma c romo l e c u l e s 1 9 8 5 , l§ , 427 -34 . Doms z y , R . C . ; A l amo , R . ; E dwa r d s , C . O . ; Mand e l k e rn , L . Ma c ro ­ mo l e c u l e s 1 9 8 6 , 12 , 3 1 0 - 2 5 . B u r c ha rd , W . P r o g r . C o l l o i d Po lyrn . S c i . 1 9 8 8 , 7 8 , 6 3 - 6 7 . Krus i , H . ; Ne ukom , H . S t a rke 1 9 84 , 3 6 , 3 00 - 0 5 . Ke i n a t h , S . E . ; Boye r , R . F . J . App l . Po lyrn . S c i . 1 9 8 1 , 2 6 , 2 0 7 7 85 . We s s on , J . A . ; Take z o e , H . ; Yu , H . ; Chen , S . P . J . App 1 . P hys . 1 982 , 53 , 6513 - 1 9 . Durning , C . J . ; T a b o r , M . Ma c romo l e c u l e s 1 9 8 6 , 12 , 2 2 2 0 - 3 2 . Muh r , A . H . ; B l a n s ha r d , J . M . V . J . F o o d T e chno l . 1 9 8 6 , 11 , 6 8 3 710. Luy e t . , B . J . J . Phys . Chem . 1 9 3 9 , 4 3 , 8 8 1 - 8 5 . R e i d , D . S . C ryo - L e t t . 1 9 8 5 , Q , 1 8 1 - 8 8 . B l a n s h a r d , J . M . V . ; F ranks , F . I n Foo d S t ru c t u r e and B e h av i o u r ; B l an s h a rd , J . M . V . ; L i l l f o r d , P . , E d s . ; A c a demi c P r e s s , Londo n , 1 9 8 7 ; pp 5 1 - 6 5 . P i ka l , M . J . ; Shah , S . ; S en i o r , D . ; Lang , J . E . J . Pha rma c e u t . S c i . 1 9 8 3 , 11 , 6 3 5 - 5 0 . P i ka l , M . J . ; S hah , S . Int . J . Pha rm . 1 9 9 0 , in p r e s s . Wh i t e , G . W . ; C a ke b r e a d , S . H . J . Fo o d Te chno 1 . 1 9 6 6 , 1 , 7 3 - 8 2 . .

260

Ill . 112. 1 13 . 1 14 . 115.

116. 1 17 . 118.

119. 1 20 .

BIOTECBNOLOGY OF AMYLODEXTRIN OLIGOSACCHARIDES

Ho l b ro o k , J . L . ; Hanove r , L . M . U . S . P a t ent 4 3 7 6 7 9 1 , 1 9 8 3 . Kahn , M . L . ; Lyn ch , R . J . U . S . P a t ent 4 5 5 2 7 7 3 , 1 9 8 5 . O r f o r d , P . D . ; P a r ke r , R . ; Ring , S . G . ; Smi t h , A . C . I n t . J . B i o I . Ma c romo l . 1 9 8 9 , 11 , 9 1 - 9 6 . R a do s t a , S . ; S ch i e rbaum , F . ; Reuthe r , F . ; Ang e r , H . S t a rk e 1 989 , � , 395 -401 . Ka r e l , M . I n F o o d P rope rt i e s and C omput e r - A i d e d En� i ne e r i n� o f F o o d P r o c e s s i n� Sys t ems ; S i ngh , R . P . ; Me d i na , A . G . , E d s . ; K 1 u ­ we r , D o r d r e cht , 1 9 8 9 ; p p 1 3 5 - 1 5 5 . F r a n k s , F . Int . Indus t . B i o t e chno 1 . 1 9 9 0 , in p r e s s . Rus s e l l , P . L . ; O l ive r , G . J . C e rea l S c i . 1 9 8 9 , lQ , 1 2 3 - 1 3 8 . Lund , D . B . I n Fo o d P rope r t i e s and C omput e r - A i d e d E n� i ne e r in� of Food P ro c e s s i n� Sys t ems ; S i ngh , R . P . ; Me d i na , A . G . , E d s . ; K l u ­ we r , D o r d r e cht , 1 9 8 9 ; p p 2 9 9 - 3 1 1 . A ra s , L . ; R i cha r d s o n , M . J . Po lyme r 1 9 8 9 , 3 0 , 2 2 4 6 - 2 2 5 2 . Doub l i e r , J . L . ; Chop l i n , L . C a rbohyd r . R e s . 1 9 8 9 , 1 9 3 , 2 1 5 - 2 2 6 .

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November 2,

1990

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Biotechnology of Amylodextrin Oligosaccharides Robert B. Friedman, EDITOR

American Maize-Products Company

Developed from a symposium sponsored by the Divisions of Carbohydrate Chemistry and of Agricultural and Food Chemistry at the 1 9 8th National Meeting

of the American Chemical S ociety, Miami Beach, Horida,

September 1 0- 1 5, 1 9 8 9

American Chemical Society, Washington, D C 1 99 1

Library or Congress Cataloging-in-Publication Data

Biotechnology of amylodextrin oligosaccharides I editor. p.

Robert Friedman,

cm.-(ACS symposium series; 458)

"Developed from a symposium sponsored by the Divisions of Carbohy!lrate Chemistry and of Agricultural and Food Chemistry at the 198th National Meeting of the American Chemical Society, Miami Beach, Florida, September 10-15, 1989" Includes bibliographical references and indexes. ISBN 0-8412-1993-1 1. Amylodextrins-Biotechnology-Congresses. 2. Oligosaccharides- BioteChnology-Congresses. I. Friedman, Robert, 1938. II. American Chemical Society. Division of Carbohydrate Chemistry. III. American Chemical Society. Division of Agricultural and Food Chemistry. IV. American Chemical Society. Meetmg (198th: 1989: Miami Beach, Fla.) V. Series. rDNLM: 1. Amylose-chemical synthesis-congresses. 2. Biotech­ 3. Dextrins-chemical synthesis-congresses. nology-congrcsses. 4. Oligosaccharides-chemical synthesis-congresses. QU 83 B616 1989] TP248.65.A46B56 1991 661 '.8-dc20 DNLM/DLC for Library of Congress

91-13893 CIP

The paper used in this publication meets the minimum r�uirements of American National Standard for Information Sciences-Permanence of Paper for Printed Library Materials, �I Z39.48-1984.