NOTE
Modified Wheat Starches Increase Bread Yield R. A. Miller,1–3 C. C. Maningat,4 and R. C. Hoseney1 Cereal Chem. 85(6):713–715
The yield of bread (amount of bread produced from a given weight of flour) is important to the commercial bread baker. Adding more water into the dough formula is an effective method of increasing bread yield with essentially no increase in processing costs. Thus, increased dough absorption is important from an economic point of view. According to the United States Food and Drug Administration Code of Federal Regulations (http://www.cfsan.fda.gov), standardized white bread produced in the United States can contain up to 38% water (USDA 2003). With most flours, it is not possible to add sufficient water in the formula to obtain bread with a final moisture content of 38%. Dough that contains excess water becomes wet and sticky and cannot be processed. In general, the amount of water lost during baking is controlled by a number of factors. These include oven temperature, baking time, surface area of the bread, and water absorption of the dough. Increased water absorption leads to higher moisture in the resulting bread and increased bread yield (Tipples and Kilborn 1968; Czuchajowska et al 1989; Puhr and D’Appolonia 1992). Dough size and shape, oven temperature, and baking time are essentially fixed in a commercial bakery. Therefore, increasing water absorption is the most practical way to increase bread yield. The water absorption of flour is determined by a number of factors including the levels of protein, arabinoxylans, and damaged starch present in the flour. Tipples and Kilborn (1968) reported that increased starch damage level and the accompanying increase in dough water absorption led to an increase in bread yield. Damaged starch imbibes water and swells at room temperature. Thus, a low level (≈5% fwb) of damaged starch has a positive effect on dough by increasing water absorption. However, at high levels (>8% fwb), the damaged starch granules interact with the gluten and change the rheological properties of the dough. The dough becomes strong but loses its elastic character. The dough is unable to expand normally during proofing and oven spring, resulting in loaves with reduced loaf volume and poor crumb grain. Added αamylase can overcome this problem by degrading the damaged starch to decrease the interaction and improve oven spring. This is the major advantage of adding α-amylase to bread flour. The degradation of the damaged starch by α-amylase also releases some of the water held by the damaged granules. Therefore, if the damaged starch level is too high, the dough becomes wet and sticky during fermentation and may produce bread with a sticky crumb. Starch can be chemically or physically modified to alter its physical properties and make it more useful in certain applications. Modifications that are commonly performed and the properties of the resulting modified starches are discussed by BeMiller (2007) and Miyazaki et al (2006). Certain of the modified starches, including pregelatinized starches, imbibe water and swell at room temperature in a manner similar to that found with 1 R&R
Research Services, Manhattan, KS 66502. Grain Science and Industry, KSU, Manhattan, KS 66506. 3 Corresponding author. Phone: 785-532-6194. E-mail:
[email protected] 4 MGP Ingredients, Atchison, KS 66002. 2 Present address: Dept. of
doi:10.1094 / CCHEM-85-6-0713 © 2008 AACC International, Inc.
damaged starch. The majority of the modified starches available are produced from corn starch. Corn starch is not compatible with gluten in breadmaking; however, wheat, rye, and barley starches are compatible with gluten (Hoseney et al 1971). Thus, modified wheat starch would be preferred in breadmaking. It is possible that certain modified wheat starches and, particularly, pregelatinized modified wheat starches might increase dough absorption in a manner similar to damaged starch but without the drawbacks described above. The modified starch may be less reactive with the gluten protein and, thus, have less effect on dough rheology. It is also possible that the modified starch would be a poorer substrate for α-amylase and not be as severely degraded during fermentation. Another approach to increasing dough absorption would be the use of the enzyme glucose oxidase which has been reported to increase dough absorption (Vemulapalli et al 1998). The objectives of this study were to determine whether bread yield could be increased by adding modified wheat starch or pregelatinized modified wheat starch to the bread formula. In addition, the effect of glucose oxidase added in combination with pregelatinized modified starch was studied. MATERIALS AND METHODS Glucose oxidase was obtained from Amano Enzymes USA (Elgin, IL). The flour used was a commercial malted bread flour containing no additives (ADM, Decatur, IL). Wheat gluten and modified wheat starches provided by MGP Ingredients (Atchison, KS) were hydroxypropylated wheat starch (H) (Midsol 40), hydroxypropylated and cross-linked wheat starch (HC) (Midsol 46), pregelatinized hydroxypropylated wheat starch (PH) (Pregel 40), and pregelatinized hydroxypropylated and cross-linked wheat starch (PHC) (Pregel 46). The hydroxypropylated starches contained 4–5% hydroxypropyl groups. The cross-linked starches were treated with a medium level of cross-linking agent. Bread was baked as pup loaves using Approved Method 1010B (AACC International 2000) straight-dough procedure with 90 min of fermentation. The bread formula consisted of flour (100 g, 14% mb), nonfat dry milk (4 g), shortening (3 g), instant active dry yeast (2 g), sugar (6 g), salt (1.5 g), and calcium propionate (0.5 g). Water absorption and mixing time were optimized for each treatment. The effect of the treatments on dough-handling properties was evaluated subjectively. Loaf volume was measured by rapeseed displacement. Proofed doughs were weighed immediately before placement in the oven. Baked loaves were weighed 1 hr after removal from the oven. The loss in weight was assumed to be moisture loss during baking. In all, four loaves of each treatment were baked in three separate bakes for a total of 12 loaves of each treatment. In one experiment, combinations of the two modified starches and pregelatinized modified starches were added to the formula. The combinations used included HC + PHC, HC + PH, H + PHC, and H + PH. Flour (10 g) was replaced with 10 g of a blend of 8.33 g of modified starch H or HC plus 1.67 g of gluten. Gluten was added to maintain the protein content of the flour. Pregelatinized modified starch PHC or PH was added at a level of 1.5% Vol. 85, No. 6, 2008
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TABLE I Effect of Modified and Pregelatinized Modified Wheat Starches on Dough and Breada Treatmentb
Water Level (% fwb)
Control HC + PHC HC + PH H + PHC H + PH a b
Dough Weight Before Baking (g)
Loaf Weight 1 hr After Baking (g)
Weight Loss During Baking (g)
Loaf Volume (cm3)
186b 192a 193a 193a 193a
157b 161a 161a 163a 162a
29b 31ab 32a 30ab 31ab
819b 865a 843ab 871a 861ab
66 72 72 72 72
Different letters within a column indicate significant differences (P = 0.05). H, hydroxypropylated wheat starch; HC, hydroxypropylated and cross-linked wheat starch; PH, pregelatinized hydroxypropylated wheat starch; PHC, pregelatinized hydroxypropylated and cross-linked wheat starch.
TABLE II Effect of Pregelatinized Modified Wheat Starches on Dough and Breada Treatmentb Control PHC PHC PHC PH PH PH a b
Level (% fwb)
Water Level (% fwb)
1.0 1.5 2.0 1.0 1.5 2.0
66 70 72 74 70 72 74
Dough Weight Before Baking (g) 186c 189b 191ab 193a 189b 190ab 193a
Loaf Weight 1 hr After Baking (g) 158c 159a–c 159a–c 160ab 157c 160ab 162a
Weight Loss During Baking (g) 29b 30ab 31a 32a 32a 31ab 33a
Loaf Volume (cm3) 845b 875ab 896ab 906ab 883ab 905ab 872ab
Different letters within a column indicate significant differences (P = 0.05). H, hydroxypropylated wheat starch; HC, hydroxypropylated and cross-linked wheat starch; PH, pregelatinized hydroxypropylated wheat starch; PHC, pregelatinized hydroxypropylated and cross-linked wheat starch.
(fwb). Preliminary baking experiments showed that these levels could be added to the flour without changing the rheological properties of the dough as determined by subjective doughhandling characteristics. Loaves containing no added starch were included as the control. In a second experiment, pregelatinized modified starches PHC or PH were added at levels of 1.0, 1.5, and 2.0% (fwb). The starch replaced an equivalent weight of flour. The same treatments were also baked in combination with glucose oxidase at 175 ppm. Loaves containing no added starch or glucose oxidase and also loaves containing glucose oxidase at 175 ppm were baked as controls. Statistical Analyses Data was evaluated using JMP Statistical Discovery Software (JMP v.5, SAS Institute, Cary, NC). RESULTS Water absorption of control doughs was 66% (fwb). Replacing a portion of the flour with modified starch, gluten, and pregelatinized starch significantly increased water absorption by 6% to a level of 72% (fwb). Preliminary experiments showed that pregelatinized starch had a strong influence on dough absorption. This was not surprising because pregelatinized starches absorb water to a greater extent than native starches. Preliminary experiments also showed that the hydroxypropylated starches used in the study had little effect on dough absorption. It was reasoned that, upon gelatinization, the hydroxypropylated starch may increase water retention in the bread. The increased absorption did not have a negative effect on the dough-handling properties of the doughs (determined subjectively). All of the doughs containing the combinations of modified starch and pregelatinized modified starches had good viscoelastic character and were not wet or sticky. Doughs containing the PH starch (HC + PH and H + PH) were softer than the doughs made with PHC starch (HC + PHC and H + PHC). Loaves containing PHC starch (HC + PHC and H + PHC) had significantly larger volumes than the control loaves but were not significantly different from loaves containing PH starches (HC + PH and H + PH). 714
CEREAL CHEMISTRY
As expected, the increased water absorption in the doughs containing the starches corresponded to an increased dough weight before baking (Table I). With the exception of loaves containing HC + PH, all loaves exhibited the same weight loss during baking. Although the loaves containing HC + PH lost more moisture than the control loaves, it was only 2.9 g more (≈1.8% of 160-g loaf). The average weight of baked loaves containing the modified and pregelatinized modified starches was higher than control loaves (Table I). Thus, the addition of the modified and pregelatinized modified starches increased bread yield by an average of 3.1% by increasing the amount of water that could be added to the dough. The next step was to investigate the effectiveness of the two pregelatinized modified starches (PH and PHC) alone. The water absorption was 66% (fwb) for control loaves. Addition of 1.0, 1.5, or 2.0% PHC or PH starch significantly increased water absorption by 4, 6, and 8%, respectively. At optimum water absorption, dough containing all three levels of PHC starch had dough-handling properties that were similar to the control doughs. At the higher levels (1.5 and 2.0%) of PH starch, the doughs were slightly sticky compared with the control doughs. As expected, the increased water absorption significantly increased dough weight before baking for loaves containing both of the pregelatinized modified starches (Table II). The higher dough absorption coupled with the relatively small loss of weight during baking and cooling resulted in a significant increase in loaf weight and therefore an increase in bread yield for loaves containing 2% PHC starch and loaves containing the higher levels (1.5 and 2.0%) of PH starch. Agents that produce hydrogen peroxide (calcium peroxide or glucose oxidase) have a drying effect on dough (Dubois and Ash 1974; Vemulapalli et al 1998). Therefore, the effect of glucose oxidase was also examined as a possible way to further increase water absorption in the dough. A glucose oxidase level of 175 ppm (fwb) was determined to be the optimum level in preliminary baking trials. The addition of glucose oxidase at 175 ppm significantly increased water absorption by 4% to a level of 70% (fwb). Surprisingly, the addition of glucose oxidase to dough containing the pregelatinized modified starches did not allow an additional
TABLE III Effect of Pregelatinized Modified Wheat Starches and Glucose Oxidase on Dough and Breada Treatmentb
Level (% fwb)
Water Level (% fwb)
Dough Weight Before Baking (g)
Control PHC + GO PHC + GO PHC + GO PH + GO PH + GO PH + GO GO
1.0 1.5 2.0 1.0 1.5 2.0
66 70 72 74 70 72 74 70
186d 190bc 189c 188cd 189c 191ab 192a 189c
a b
Loaf Weight 1 hr After Baking (g) 158b 158b 159ab 156c 158b 161a 159ab 158b
Weight Loss During Baking (g) 29c 33a 30ab 33a 32ab 30ab 33a 32a
Loaf Volume (cm3) 846a 862a 876a 873a 899a 908a 874a 866a
Different letters within a column indicate significant differences (P = 0.05). H, hydroxypropylated wheat starch; HC, hydroxypropylated and cross-linked wheat starch; PH, pregelatinized hydroxypropylated wheat starch; PHC, pregelatinized hydroxypropylated and cross-linked wheat starch; GO, glucose oxidase at 175 ppm (fwb).
increase in absorption. The reason for this was unclear. Increasing water absorption in dough containing either of the pregelatinized modified starches plus glucose oxidase to levels above the optimum level obtained with the starches alone caused the dough to become sticky and unmanageable. The addition of glucose oxidase to doughs containing either of the pregelatinized modified starches at their optimum absorption did not affect doughhandling properties or loaf volume (Table III). The addition of glucose oxidase also significantly increased dough weight (Table III). However, glucose oxidase appeared to increase moisture loss during baking and cooling. The reason for this was unclear. As a result, loaves containing glucose oxidase alone or in combination with the pregelatinized modified starch had higher water absorption and dough weight but did not have a heavier baked weight than control loaves. In comparing weight of baked loaves containing pregelatinized modified starch with and without glucose oxidase (Table II vs. Table III), loaves containing glucose oxidase were lighter. Thus, glucose oxidase did not improve bread yield and reduced the effectiveness of the pregelatinized modified starches. SUMMARY Bread yield was increased by adding either a combination of modified and pregelatinized modified wheat starch or pregelatinized modified starch to the formula. The starches increased dough water absorption without causing any noticeable effect on dough-handling properties or loss of loaf volume. The higher dough absorption coupled with a relatively small loss of weight during baking and cooling resulted in a significant increase in loaf weight and therefore an increase in bread yield.
Glucose oxidase increased dough absorption but did not allow an additional increase in absorption of doughs containing pregelatinized modified starch. Glucose oxidase appeared to increase moisture loss during baking and cooling. Thus, glucose oxidase did not improve bread yield when used alone and did not increase the improvement in bread yield over that of pregelatinized modified starch alone. LITERATURE CITED BeMiller, J. N. 2007. Carbohydrate Chemistry for Food Scientists. 2nd Ed. AACC International: St. Paul, MN. Czuchajowska, Z., Pomeranz, Y., and Jeffers, H. C. 1989. Water activity and moisture content of dough and bread. Cereal Chem. 66:128-132. Dubois, D. K., and Ash, D. J. 1974. Encapsulated calcium peroxide for continuous bread process. Baker’s Dig. 48(3):40-41, 59. Hoseney, R. C., Finney, K. F., Pomeranz, Y., and Shogren, M. D. 1971. Functional (breadmaking) and biochemical properties of wheat flour components. VIII. Starch. Cereal Chem. 48:191-201. Miyazaki, M., Hung, P. V., Maeda, T., and Morita, N. 2006. Recent advances in application of modified starches for breadmaking. Trends Food Sci. Technol. 17(11):591-599. Puhr, D. P., and D’Appolonia, B. L. 1992. Effect of baking absorption on bread yield, crumb moisture, and crumb water activity. Cereal Chem. 69:582-586. Tipples, K. H., and Kilborn, R. H. 1968. Effect of pin milling on the baking quality of flour in various breadmaking methods. Cereal Sci. Today 13:331-334, 336. USDA. 2003. Part 136. Bakery products. Subpart B—Requirements for Specific Standardized Bakery Products. Paragraph 136.110, Bread, Rolls and Buns. GPO: Washingon, DC. Vemulapalli, V., Miller, K. A., and Hoseney, R. C. 1998. Glucose oxidase in breadmaking systems. Cereal Chem. 75:439-442.
[Received December 10, 2007. Accepted May 29, 2008.]
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