assist in the collection of both sensory and analytical data. A short format has been devised for describ ing the sulphury characteristics of beer flavour. Methods ...
J. Inst. Brew.. November-December, 1985, Vol. 9\,pp. 364-369
364
DEVELOPMENT OF ROUTINE INVESTIGATIONAL TOOLS FOR THE STUDY OF SULPHURY FLAVOURS IN BEER Bv T. L. Pkppard*
(Brewing Research Foundation, Nulfield. Surrey. UK) Received 24 December 1984
A number of investigational tools are described, for characterising sulphury flavours in beer; these assist in the collection of both sensory and analytical data. A short format has been devised for describ ing the sulphury characteristics of beer flavour. Methods of data processing which determine whether or not a panel has discriminated between two or more beers, when using descriptive flavour analysis, are outlined. An analytical method has been devised for detecting and quantifying certain flavouractive organosulphur volatiles in beer. The technique, which is based on a purge/trap/desorb procedure, requires minimal modification of existing capillary GC equipment. Key words: Beer (analysis method for), flavour. flavour profile, gas chromatography, statistical analysis, sulphur compound, sulphuryflavour. Introduction
In recent years, tremendous advances have been made in the analytical methods available Tor concentration, separation and characterisation of beer flavour constituents. Thus,
the number or such substances identified now exceeds 800.'2
However, many of the components which are present at the
highest levels are relatively unimportant, in terms or the contribution which they make to the overall flavour impres sion of beer. Conversely, certain groups of compounds, such as aldehydes and those containing sulphur, are highly flavour-potent and, though frequently present at levels well below 1 ppb, can have a major influence on beer flavour. Progress towards the characterisation of beer flavour generally involves three distinct phases. The first is to obtain
sensory data from which genuine differences between beers
whilst research into the area of beer staling employed short
format of 14 descriptors.1-20 In the present studies, it was
once again felt appropriate to design a shortened format, suitable for describing the sulphury characteristics of beer flavour. Following sensory evaluation of a range of sound and defective beers from both commercial and pilot breweries by a panel of experienced tasters, a format designed specifi cally to describe sulphury flavour was drawn up (see Figure I). Clearly, not all sulphury beers exhibit every one of the 7 Name:—
Dale:—
Beer No:—
Time:— BREWING RESEARCH FOUNDATION SULPHURY FLAVOUR PROFILE
Inlensity Scale: 0 ubscnl
A—Mandatory (please fill in all boxes in this section)
can be described, and for this flavour profile analysis has
Aroma
been the method of choice.2'8 The second phase is the
collection of relevant analytical data; frequently this is achieved using an instrumental technique, such as gas chromatography (GC), which measures a number of analytes simultaneously. Finally, the third phase is to seek correlations between sensory and analytical data. The present paper describes the development of routine invcstigational tools, designed to assist in these areas when characterising sulphury flavours in beer. Results and Discussion Descriptive Flavour Analysis J. A Short Format for Sulphury Flavours.—Descriptive Flavour Analysis (frequently referred to as Flavour Profile Analysis) is now well established in the area of flavour assessment, being used both for quality monitoring and for
investigational or product development work.2'8 For such
purposes numerous formats have been designed. These for mats often differ markedly in appearance, with great variety in the number and type of descriptors used, the type of intensity scaling employed and whether or not subjective
9 extreme
0720
Sulphidic(H,S)
0724
Lightstruck
0726
Rubbery
0730
Cabbagy
0732
DMS
0736
Onion-like
0741
Meaty
Tasie
B—Optional (for other prominent flavours) Aroma
Taste
judgements of quality and preference are included. For example, one format currently in use at the BRF requires assessors to score 38 terms for aroma and 31 terms for taste, using a category scale running from 0 to 10. However, in
connection with specific research topics, it is often advan tageous to direct assessors' attention to particular aspects of flavour, using a shortened format which comprises an appropriate selection of flavour descriptors. Thus, in the past, studies connected with hop character have been
carried out using a short format of 10 relevant terms,8 'Present address: The Stroll Brewery Company, Detroit, Michigan, USA.
Fig. I. Short Format used for Descriptive Analysis of Sulphury Flavours.
Vol.91, 1985]
characteristics listed in the mandatory part (A) of the form. However, it was considered that the majority of such beers could be adequately described within the framework of the format. Even so, it was decided to provide assessors with the
optional part (B) of the form for scoring additional flavour notes. These might be abnormal sulphury characteristics, not readily described in terms of the descriptors listed in part A. Alternatively, they could be other prominent flavour notes which, though not themselves sulphury in nature, might have a marked influence on the perception of
genuine sulphury characteristics, e.g. by masking. Allowing tasters to score other flavour notes in part B can also help to overcome the physchological difficulties experienced by an assessor having to submit a completely blank form, in the case where no sulphury characteristics have been identified!
Flavour terms cannot be adequately defined other than by the use of reference standards. For example, 27 such standards have so far been adopted for use in connection with the system of terminology developed jointly by work
ing groups of the ASBC, the EBC and the MBAA.1314
Reference standards used in the present studies are shown in TABLE 1. Reference Standards for Sulphury Flavours Flavour Descriptor
Reference Standard
0720Sulphidic(H2S) 0724 Lightstruck
aq. sodium sulphide (for aroma only) 3-mcthyl-2-butenc-l-thiol and authentic lightstruck beers 2-furfuryl mercaptan methyl thioacelate dimethyl sulphide dimethyl trisulphide thiaminc (for aroma only)
0726 Rubbery 073OCabbagy 0732 DMS 0736 Onion-like 0741 Meaty
365
peppard: sulphury flavours in beer
Table I, although it is recognised that in some cases the sub stances indicated are responsible for flavour notes which do not entirely match those occurring 'naturally' in beer. Clearly this is an area in which more appropriate reference standards should become available, as the less common sulphury flavours in beer are characterised. 2. Evaluation of Results.—The results obtained for a
series of beers by descriptive flavour analysis, are most simply presented in tabulated form, or as histograms. However, it is important to determine the significance (or otherwise) of apparent differences between beers. In this respect, the use of so-called 'cobweb plots' is a significant improvement, since it indicates both the mean panel score and the 95% Confidence Interval for each descriptor
on each beer.10'11 This type of visual presentation of
results has also been used in conjunction with parametric statistical tests, in order to determine whether or not there are significant differences between beers. It is generally accepted that data generated by sensory
analysis are not parametric, i.e. they do not derive from any particular type of distribution. Consequently this kind of data should be analysed using non-parametric statistical procedures. Accordingly, in the present studies, a series of suitable computer programs (collectively designated as FLA VSTAT) was written, in BASIC, for use with an Apple II microcomputer (see Experimental section). These pro grams allow the entry, editing and storage of data from descriptive flavour analysis; printer output indicates the computed panel means and totals, together with the raw data actually recorded by individual assessors. In addition, however, FLAVSTAT carries out non-parametric statistical tests to determine the significance of apparent differences between beers. The statistical procedures employed by FLAVSTAT are
based on so-called Randomization Tests,6 which make no
assumptions about the distribution of the data. These tests are procedures for determining statistical significance direc tly from experimental data, without recourse to significance tables. The data are permuted or divided repeatedly, on a random basis, between beers. For each permutation of the data, a test statistic (e.g. t or F) is computed to determine the proportion of data permutations which provide as large a test statistic value as that associated with the original experimental results. If that proportion is as small as sig nificance level P, then results are significant at the P level. In the case of a comparison between two beers, the equivalent of a t-test is employed, whilst for three beers the equivalent of an analysis of variance (ANOVA) is carried out. Where
the latter indicates a possible significant difference between beers, each pair is subjected to the t-test. An example of the printout is obtained using FLAVSTAT is given in the Appendix. In this particular case, the comparison is between two beers aged for 15 weeks at 18°C and one beer aged for the same length of time at 0°C. The results indicate that beer nos. 2 and 3 are significantly more cabbagy than beer no. I, with P=0-0l2 for aroma and P=0-053 for taste. The raw data obtained by individual assessors (rarely shown in publications!) illustrates a number of points. First, there is a degree of confusion amongst tasters regarding the language used to describe perceived flavours, although the latter will vary genuinely to some extent from one taster to the next. Secondly, even when assessors appear to agree on their choice of descriptor, the use of intensity ratings varies widely. With these factors in mind, an option was built into FLAVSTAT, that enables combination of individuals' scores for selected flavour descriptors, and allows statistics to be carried out on these combined data. The Appendix illustrates the effects of combining: (i) cabbagy and onionlike aromas, (ii) all sulphury aroma notes, except DMS. Clearly, the results of statistics on such combined data must be interpreted with caution, as combination is carried out with the benefit of hindsight. Also, combining flavour notes inevitably leads to loss of some descriptive information. The method described above for processing data obtained by descriptive flavour analysis, is most suited to the comparison of a small number of beers, tasted ideally within the same session. If required, replication can be achieved simply by repeating the session. However, on occasions the number of beers to be compared is more than can realistically be tasted within one session. Then it is necessary to choose an appropriate experimental design,
such as one of the many listed by Cochran and Cox.4 The choice will ultimately depend on the total number of beers to be compared, the number of replicate analyses required for each, and the number of samples to be tasted within any one session. In these studies, results from descriptive flavour analysis of a number of beers (including replicates), accumulated during the course of several tasting sessions,
were
subjected
to
principal
components
analysis
(PCA).3-17'19-21 This technique enables graphical represen
tation of the similarity/dissimilarity between beers by one or more plots on 2-dimensional Cartesian co-ordinates. It allows investigation of the underlying relationships which exist between individual flavour notes, and moreover enables interpretation of observed similarity/dissimilarity in terms of the latter. Figures 2a and 2b illustrate the use of PCA for deter
mining the ability of a panel to discriminate between the sulphury characteristics exhibited by a series of 7 ales. All beers were tasted on 3 occasions, in accordance with an
incomplete block design which involved 7 tasting sessions with 3 beers assessed in each, so that ultimately each beer was compared against every other. Therefore in Figure 2a, the different beers are represented by 7 triangles with the replicate analyses as vertices. Clearly, 7 relatively small, well-separated triangles would indicate the panel's ability to discriminate successfully between all beers. On the other
366
[J. Inst. Brew.
peppard: sulphury flavours in beer
second component
(261%)
first component
(32-6%)
b)
second component (26 1%)
6
•
4 first component
•
3
(32 6%)
Fig. 2. Result of Principal Components Analysis on Descriptive Data from 7 Beers: (a) Standardised Component Scores (b) Component Loadings on the first two principal component axes. • = aroma, O = taste; I = lightstruck, 2 = sulphidic (H2S), 3=rubbery,
4=cabbagy, 5 = DMS, 6=onion-like, 7=meaty.
hand, large over-lapping triangles are indicative of poor dis crimination. Therefore, in the present example, the panel has been able to discriminate to some extent between all beers except W and E. Beers L and S are particularly well separated from the remainder (and each other), although one replicate of beer S showed rather poor agreement with the other two. As judged by the positions of the beers rela tive to the original variables (compare Figure 2a with 2b), beer L was characterised by DMS flavour, whilst beer S was characterised by sulphidic and rubbery flavour notes. One further interesting observation from the results of PCA, was the closeness in relative positions of aroma and taste aspects for all descriptors. Clearly, with the results of aroma and taste being so highly correlated, there is a case for evalu ating sulphury flavour by aroma only, therefore lessening the problems which can arise due to taste carry-over from one sample to the next. In the past, the use of multivariate techniques such as PCA has largely been restricted to those workers with access to mainframe computers and sophisticated statistical packages. Nowadays, however, it is possible to purchase software enabling PCA to be run on laboratory micro computers. Consequently, the technique is now potentially available to most researchers, as a routine data processing
aid. Instrumental Analysis ofOrganosulphur Volatiles
Numerous methods have been devised for the concen tration, separation and estimation of volatile beer flavour
constituents. The trend within recent years, however, has
been towards the use of so-called purge/trap/desorb (PTD)
systems.16 These involve purging volatiles from beer with
inert gas, into a cold trap or a trap packed with adsorbent material. After a suitable collection period, volatiles are desorbed from the trap by heating in a stream of inert gas, and are transferred directly into a gas chromatograph for analysis. In systems which employ adsorbents, the desorption process can last up to 20 minutes. In such cases, the volatiles are either re-collected in an intermediate cold trap, or are 'thermally focused' at the front end of the chromatographic column, often cooled to well below 0°C. In the present studies, the aim was to develop a PTD system, suit able for the analysis of sulphur volatiles, with minimal modification of existing equipment, a Finnigan 1020 GC-MS instrument fitted with a flame photometric detector (FPD) and cryogenic GC oven cooling (capable of giving oven temperatures as low as — 50°C). Modifications of, and additions to the existing equipment are described in the Experimental section, as are the pro cedures followed. Porapak Q was chosen as the adsorbent, in preference to either Tcnax GC or Chromosorb 102, since it gave rather better recoveries for sulphur volatiles. In separate studies however, dealing with other less volatile beer flavour constituents, Tenax GC was the adsorbent of choice. During the procedure, volatiles desorbed from the Porapak Q trap are re-condensed as a narrow band at the front end of a fused silica capillary column cooled to — 30°C (so-called 'thermal focusing'). The type of capillary column selected was one with a chemically bonded stationary phase,
CP Wax 57CB™. This phase is suitable for use at low
Vol.91, 1985]
temperatures, and its performance is not seriously impaired
by traces of water which arc inevitably introduced into the
column along with the volatiles.5 In order to avoid the
phenomenon of peak-splitting, which tends to occur with sub-ambient use of a capillary column, the latter was placed in a collar made from aluminium foil and asbestos paper as
described by Mooney.iS
The sensitivity of the method depends on the analyte under investigation, but detection limits of less than 0-25 ug/litre are readily achieved with sulphur volatiles such as diethyl sulphide, ethyl thioacctate, diallyl sulphide and diethyl disulphidc. When purging was carried out with two adsorbent tubes in scries, the percentage of trapped material in the first tube varied from 50-100% (although mostly nearer the upper figure), depending on the nature of the analyte. However, the reproducibility of the technique generally appears to be quite acceptable. In 11 analyses, the
ratio of two sulphur compounds (diisopropyl sulphide and S-methyl heptanethioate), added to beer to give a level of I -25 ug/litre, had a coefficient of variation of 26%, or 13% when two results were rejected as outliers. Unfortunately the method in its present form is not suitable for the most highly volatile sulphur compounds in beer, such as hydro gen sulphide and methanethiol. That this might be due to
contact with the hot stainless steel injection needle (see Experimental Section) was one possibility. However the situation was not rectified when the stainless steel needle
was replaced by one made from platinum, which is a more inert metal. Instead, poor retention of such volatiles on the Porapak Q trap seems likely. Beer packaged in clear or green glass bottles, on exposure to daylight or light from a number of artificial sources, is susceptible to the formation of a flavour described as
lightstruck or sunstruck.9 The PTD procedure has been used to detect the presence of 3-methyl-2-butene-l-thiol,7 in beer which had been damaged by over-exposure to light. Figure 3a shows part of the FPD chromatogram obtained by analysis of an imported lager (bottled in green glass) as purchased from a local supermarket. Figure 3b shows the marked
367
peppard: sulphury flavours in beer
increase
in
level
of 3-methyl-2-butene-l-thiol, c
e
occurring after an additional 1 hour exposure to diffuse daylight. Both samples of beer had a pronounced lightstruck flavour. Experimental
Sensory Analysis.—Descriptive flavour analysis was carried out by panels of 8 trained assessors, using the short format for sulphury flavour shown in figure 1. In view of the transient nature of some sulphury flavours, beers were assessed immediately after dispense into glasses. Processing
of Sensory
Data.—Data
processing
was
carried out using an Apple II Plus microcomputer with 48K
of memory, and the DOS 3-3 operating system. The micro computer was equipped with an Epson MX-80 F/T matrix
printer, connected through an EP12-80/100 (PKASO™) printer interface (Interactive Structures Inc., Bala, PA,
USA), and three 5{ inch floppy disc drives. The program for
carrying out principal components analysis was part of a commercial software package (Personal Computer Soft ware Ltd., London, UK); other programs were written by the author in Applesoft BASIC, and were designed to be compatible with the commercial software. Instrumental Analysis of Sulphur Volatiles in Beer
Reagents.—The antifoam used was as a solution of 10% silicone DC anlifoam RD emulsion (Hopkin and Williams, Romford, Essex, UK) in water. The internal standard solution comprised 005ul diisopropyl sulphide (Aldrich, Gillingham, Dorset, UK) dissolved in 100 ml absolute ethanol (AR grade, James Burrough, London, UK).
The nitrogen used was OFN grade (BOC, London, UK) further purified through an activated charcoal filter (Alltech Associates, Carnforth, Lanes, UK). Porapak Q (50 mg, 50-80 mesh) (Waters Associates, Northwich, Cheshire, UK), held between two plugs of silanized glass wool (Phase Separations, Queensferry, Clwyd, UK) in a glass injection port liner (87 mm x 7 mm o.d. x2mm i.d.), was purged before use by heating to I8O°C in a stream of helium.
Equipment.—Volatiles were thermally desorbed from Porapak Q traps using the small rapid heating unit, shown diagrammatically in figure 4. Thermal focusing and subsequent gas chromatographic separations were carried out using a Finnigan 1020 GC-MS
system, fitted with a flame photometric detector (394 nm
*mw
A
C
^PTffrVfT^P
EF
s
filter). The oven had the facility for sub-ambient operation (down to -SOX) employing cooling with liquid carbon dioxide. Chromatography was performed with a 25 metre x 0-3 mm i.d. fused silica WCOT column, with a chemically
bonded stationary phase, CP Wax 57CB™, of 1 -2 micron
>**»4f W
film thickness (Chrompack, London, U.K.). Helium (CP grade, BOC) was used as carrier gas, at an inlet pressure of 14 psi. Injector and detector temperatures were set at 150°C; the temperature programme operated is described below. Data were collected and processed using an HP3390A electronic integrator (Hewlett-Packard, Wokingham, Berks, UK).
12
16
20
TIME (mm)
Fig. 3. Sections of Gas Chromalograms obtained using Purge/Trap/ Desorb Procedure: (a) bottled lager, as purchased from local supermarket (b) bottled lager, as above but further exposed (I h) to diffuse daylight.
Identities of Peaks: A = diisopropyl sulphide (internal standards), B = clhanol, C = methyl thioacetatc, D = dimethyl disulphidc, E=ethyl thioacctate, F = 3-mcthyl-2-butcne-l-thiol, G= unknown.
Procedure
I. Purge and Trap Stage.—Beer (400 gm), containing 5
drops of antifoam solution, was placed in a one litre round-
bottomed flask and spiked with 1 ml of internal standard
solution, to give a level of 1.25 ppb diisopropyl sulphide.
The flask was fitted with a Drcchsel head with an inlet tube drawn out to a fine point and situated below the surface of the beer (see Figure 5). The Porapak Q trap was then butted up against the outlet tube of the Drechsel head, and a leaktight connection ensured by means of a short length of PVC
368
[J. Inst. Brew.
peppard: sulphury flavours in beer
Scale- 1 cm Stainless Steel Needle luei Fitting
PTFE Seal Glass Injection Linor
Glass Wool Plug Heating Block-
3. Gas Chromatographic Separation.—The full temperature programme employed during analyses was as follows:
(i) 10min hold at
Porapak Q
-30°C (during desorb and thermal
focusing stage) (ii) - 30°C to 60°C, ramped at 30C/min (iii) 60cC to 200°C, ramped at 3°C/min
Stainless Steel Casing— To Power Supply
Thermocouple
PTFE Seal
volatiles were being desorbed from the Porapak Q, carried through the injection port of the gas chromatograph and re-condensed as a narrow band at the front end of the cooled capillary column. At the end of the 10 minute period, the injection needle was withdrawn, the carrier gas supply turned on and the injection split and septum purge valves re-opened. In addition, the temperature programme moved automatically into a rapid heating phase (30°C/min).
Spiing Loaded Retainer
Acknowledgements.—The author wishes to thank, Mr A. J. Bennett for construction of the rapid heating unit, Mr C. W. Towner for technical assistance and the Director of the Brewing Research Foundation for permission to publish this paper. References
1. Barrett, J.. Halsey, S. A. & Pcppard. T. L.. Journal of the Institute
ofBrewing. I983,'89, 356.
2. Clapperton, J. F., Journal ofthe Institute ofBrewing, 1973.79,495. 3. Clappcrton. J. F. & Piggolt, J. R.. Journal of the Institute of
Helium Supply
Fig. 4. Purge/Trap/Dcsorb Procedure. The Rapid Heating Unit.
PVC Tubing
3-WayTap
To Flow Meier
Purified Nitrogen (lOOml/min)
Porapak Q Trap Drechsel Head
Beer (400 gm) -
-Water Bath (30 C)
Fig. 5. Purge/Trap/Dcsorb Procedure. Purging Beer Volalilcs onto Porapak Q Trap.
tubing. The flask was stood in a water-bath thermostatted at 30°C, and the inlet tube of the Drechsel head connected to a supply of purified nitrogen. The flow rate was set at ca 100 ml/min, as measured at the outlet end of the Porapak Q trap. Purging of beer volatiles onto Porapak Q was con tinued for 1 h, during which time the flow rate was monitored. 2. Desorb and Thermal Focusing Stage.—After 1 h, the trap was removed from the Drechsel head and placed, with its orientation reversed in relation to the direction of gas flow, inside the rapid heating unit shown in Figure 4. Helium, at a pressure of 10 psi, was allowed to flow through the trap for 30 sec, in order to flush out entrapped air. In the meantime, the supply of helium carrier gas to the capillary column (previously cooled to — 30°C) was shut off by means of a toggle valve. In addition, the injection split and septum purge valves of the gas chromatograph were also shut. At the end of 30 sec, the injection needle on the front of the desorb oven was inserted through the injection septum of the gas chromatograph. Simultaneously, the 10 minute initial holding period of the temperature programme was started, and rapid heating (ambient to 165°C in ca 2-5 min) applied to the desorb oven unit. During this period,
Brewing. 1979.85,271. 4. Cochran. W. G. & Cox. G. M.. Experimental Designs. New York: Wiley & Sons Inc., 1957. 5. de Nijs, R. C. M. & Dc Zeeuw. J., Journal of High Resolution Cliromatography ami Cliromatographv Communications, 1982. 5, 501. 6. Edgington. E. S.. Randomization Tests. New York: Marcel Dckker Inc.. 1980. 7. Gunst, F. & Verzele, M.. Journal of the Institute of Brewing. 1978, 84,291. 8. Hudson, J. R., European Brewery Convention—Monograph VII. Flavour Symposium, Copenhagen. 1981.17. 9. Kuroiwa. Y., Hashimoto. N., Hashimoto. H.. Kokubo. E. & Nakagawa. K.. Proceedings of the American Society of Brewing Chemists. 1963.181. 10. Malek, D. M., Schmitt. D. J. & Munroe, J. H., Journal of the American Society of Brewing Chemists, 1982,40, 133. 11. Mecredy. J. M., Sonnemann, J. C. & Lehmann. S. J.. Brewers Digest. 1975.50(6), 42. 12. Mcilgaard. M. C., in Brewing Science. I'olume 3. Pollock, J. R. A. (ed). London: Academic Press 1985, in press. 13. Meilgaard. M. C, Dalgliesh, C. E. & Clapperton. J. F.. Journal of
the Institute of Brewing. 1979,85, 38. 14. Meilgaard. M. C. Reid. D. S. & Wyborski. K. A., Journal of the American Society of Brewing Chemists. 1982,40,119. 15. Mooney, S. A.. Journal of High Resolution Chromatography and Chromatography Communications, 1982,5,507. 16. Nunez, A. J., Gonzalez, L F. & Janck, J., Journal of Chromalography. 1984.300,127. 17. Pangborn. R. M., in Flavour '81. Proceedings of the 3rd Weurman Flavour Symposium. Munich' Schreier. P. (ed). Berlin: Walter dc Gruyter. 1981.3.
18. Peppard, T. L, Journal of the Institute of Brewing 1985,91,16. 19. Peppard, T. L., Journal of the Institute of Brewing, in press. 20. Peppard, T. L.. Buckee. G. K. & Halsey. S. A., European Brewery Convention. Proceedings ofthe 19th Congress. London. 1983, 549. 21. Vuataz, L, Nestle Research News. 1976/77, 57-71.
APPENDIX
DESCRIPTIVE FLAVOUR ANALYSIS Date: 09/11/83 Beer I: Control—Aged 15 weeks at 0 Degs. Beer 2: Control—Aged 15 weeks at 18 Degs. Beer 3: Test—Aged 15 weeks at 18 Degs.
Tasters:ABCDEFGH
Time: 11
Vol. 91, 1985]
369
peppard: sulphury flavours in beer
FLAVOUR NOTE COMB!NATIONS AROMA TASTE
SULPHURY FORMAT—IRAW SCORES (& TOTALS) AROMA BEER I BEER 2 BEER 3 Sulphidic 00000003 (3) 20300000 (5) 20000002 Lighlstruck 00000000 (0) 00000000 (0) 00000000 Rubbery 00000000 (0) 02000000 (2) 00000020 00000042 (6) 06452534 (29) 04561345 Cabbagy 00200167 (16) 00003000 (3) 02000000 DMS 00000000 (0) 50000200 (7) 3O3OIO00 Onion-like Meaty 00000000 (0) 00100045 (10) 00000002 BEER1 BEER 2 BEER 3 TASTE Sulphidic 10000002 (3) 10000000 (I) 10000004 00000000 (0) 00000000 (0) 00000000 Lightstruck Rubbery 00000200 (2) 04000000 (4) 00000200 Cabbagy 10000002 (3) 02322203 (14) 00233202 DMS 00200205 (9) 00002200 (4) 05000300 Onion-like 00000000 (0) 30000020 (5) 10002000 00000000 (0) 00200001 (3) 00000001 Meaty
1. 2. 3. 4. 5. 6. 7. 8.
(4)
(0) (2) (28)
(2) (7) (2)
(S) (0) (2) (12) (8) (3) (1)
Sulphidic Lighlstruck Rubbery Cabbagy
9. 10. II. 12. 13. 14. 15. 16.
DMS Onion-Like Mealy All
BEER 3 A T 0-5 0-6
Lighlstruck
Rubbery
Cabbagy
0-8 20
DMS
Onion-like Meaty
0-3 0-4 II
0-3 3-6 04 0-9 1-3
03 3-5 03 09
0-5 1-8 05 06 04
0-3
0-3 1-5 10 0-4 01
ANOVA/T-TEST (ON RAW SCORES) MAXIMUM NUMBER OF PERMUTATIONS: 5000
46 123467
i
ANOVA/T-TEST (ON COMBINED FLAVOUR NOTES) MAXIMUM NUMBER OF PERMUTATIONS: 5000
GROUP 1 2
2V3 — — — >0 5 >0S >0-5 0-306 2V3 — —
IV3 — — — 0013 0178 0185 >0-5 I V 3 — —
IV2 — — — 0 0113 0-238 0-482 0-218 IV 2 — —
Cabbagy DMS
>0-5 —
0095 —
0031 —
Rubbery
Onion-like Meaty
>0-5
0053 >0-5
0-462 >0-5
STAR RATINGS: AROMA ANOVA T-TESTS:
Sulphidic Lightstruck Rubbery Cabbagy DMS Onion-like
Meaty TASTE Sulphidic Lightstruck
Rubbery
Cabbagy DMS Onion-like
Meaty
N.S.D. N.S.D. N.S.D.
N.S.D. N.S.D. N.S.D. ANOVA T-TESTS: N.S.D. N.S.D.
N.S.D i
N.S.D. N.S.D. N.S.D
Star Rating Key: N.S.D.—P > 0-100 !—P< =0-100 •—P< =0050 ••—P0-5 —
0 474 —
0-47 —
2V3
IV3
1V2
N.S.D. N.S.D. N.S.D N.S.D. 2V3
• N.S.D. N.S.D. N.S.D. 1V3
* N.S.D. N.S.D. N.S.D IV2
N.S.D.
!
*
N.S.D.
N.S.D.
N.S.D.
ANOVA T-TEST: 0 0004 00004
STAR RATINGS: GROUP ANOVA T-TESTS: 1 • * • 2 • • • Star Rating Key: N.S.D.—P>OIOO !—P0-5 Rubbery >0-5 Cabbagy 0012 DMS 012 Onion-iike 0 366 Meaty 0165 TASTE ANOVA T-TESTS: Sulphidic >0-5 Lightstruck >0-5
DMS Onion-like Meaty All
FLAVOUR NOTES
GROUP 1
PROBABILITIES:
SULPHURY FORMAT—PANEL MEANS BEER I BEER 2 A T A T Sulphidic 0-4 0-4 0-6 01
Sulphidic Lightstruck Rubbery Cabbagy
2V3 >0S
IV3 0 0016 00036
IV2 00012 00016
2V3 N.S.D. N.S.D.
I V3
1 V3
0-344
