Can. Inst. Food set. Technol. J. Vol. 16, No. 3, pp. 201-205, 1983

Preparation, Composition and Functional Propertiesof Oat Protein Isolates

1

Ching-Yung Ma

Food Research InstituteAgriculture Canada

Ottawa, Ontario KIA OC6

AbstractProtein isolates were prepared from dehulled, defatted groats of

Hinoat and Sentinel oats by two methods: isoelectric precipitation of analkaline extract (alkaline isolate) and dialysis or dilution of a salt extract(salt isolate). Both types of isolates contained over 900/0 protein (N x5.80), but the yield of N was much higher in alkaline isolate (over 60%)than salt isolate (25%). There was no sigificant difference in the proxi­mate chemical compositions of the isolates from the two oat varieties.Both types of isolates had similar amino acid composition, althoughalkaline isolate had slightly higher lysine and total essential amino acidcontents than salt isolate. Some functional properties of the isolates wereassessed and compared to wheat gluten and soy protein isolate. Theresults indicate that the oat isolates had high fat binding capacity andgood foaming properties.

ResumeDes isolats de proteines ont ete prepares seIon deux procedes, a partir

. de caryopses d'avoine (var. Hinoat et Sentinel) degraisses et decorti­ques: par precipitation isoelectrique d 'un extrait alcalin (isolat alcalin) etpar dialyse ou dilution d'un extrait salin (isolat salin). Les isolatscontenaient tous deux au-dela de 90% proteines (N x 5.80) mais lerendelnent en N etait de beaucoup superieur pour I' isolat alcalin (plus de60%) en comparaison acelui de l'isolat salin (25%). On n'a pas observede difference significative dans les analyses approximatives des isolatsdes deux varietes d' avoine. Les deux types d' isolats possedaient unecomposition semblable en acides amines; par contre, l'isolat alcalinavait un contenu de lysine et d' acides amines totaux superieur acelui del'isolat salin. Quelques proprietes fonctionnelles des isolats ont eteetudiees et comparees acelles du gluten de ble et de I'isolat de proteinesdu soja. Les resultats demontrent une grande facilite alier les gras et debonnes proprietes mousseuses pour les isolats d' avoine.

Introduction

Oats have been used essentially for animal feed,although oat proteins have been shown to have goodnutritional value (Hischke et al., 1968) and can be usedmore widely for human consumption. Compared to othercereals, oats provide a relatively cheap source of proteinswhich do not contain antinutritional factors found in someplant protein sources. Protein concentrates and isolateshave been prepared from oats by different procedures(Cluskey etal., 1973, 1978; Wu and Stringfellow, 1973;Youngs, 1974; Wu et al., 1977; Bell et al., 1978), butthere is limited information on the chemical and function-

IContribution No. 509. Food Research Institute, Agriculture Canada.

al properties of oat proteins. In this work, protein isolateswere prepared from a high and moderately high proteincontent oat cultivar, Hinoat and Sentinel, respectively, bytwo different procedures. One procedure involvedisoelectric precipitation of an alkaline extract, and theother dialysis or dilution with water of a salt extractsimilar to that described by Murray et al. (1978, 1981).The chemical compositions and functional properties ofthe isolates were determined to assess the potential of oatproteins as a food ingredient.

Materials and MethodsTwo oat varieties, Sentinel and Hinoat, were grown at

the Central Experimental Farm, Ottawa, in 1980 and1981, respectively. The oats were dehulled, ground in acoffee grinder, and defatted by Soxhlet extraction withhexane.

Salt soluble protein isolates were prepared by theprocedure as described by Murray et al., (1978,1981).The ground groats were mixed with 0.5 M CaCl2 at agroat solvent ratio of 1: 10 (w:v). The slurry was stirred for60 min at room temperature and centrifuged at 6000 x gfor 20 min. The supernatant was either dialyzed againstcold running tap water or diluted with water. The salt­soluble proteins (salt isolate, SI) which precipitated, werecollected by centrifugation and freeze-dried.

Isoelectrically precipitated alkaline isolates were pre­pared by mixing the groats with dilute NaOH (0.015 N) ata groat solvent ratio of 1:8 (w:v); which gave an initial pHof 9.5. The slurry was stirred at room temperature for 60min and centrifuged at 4000 x g for 10 min. The super­natant was neutralized with 2 N HCl to pH 5.5, recentri­fuged, and the alkaline isolate (AI) residue and alkalinesupernatant (AS) were freeze-dried.

Nitrogen was determined by the microKjeldahlmethod (Concon and Soltess, 1973), converted to proteinusing a conversion factor of 5.80 (Tkachuk, 1969), andthe protein content was expressed as a percentage of thesample dry weight. Carbohydrate contents were estimatedby the phenol-sulphuric acid method (Dubois et al.,1956). Moisture, ash and fat were determined by AACC

Copyright 1983 Canadian Institute of Food Science and Technology

201

(1971) approved methods. Amino acid analyses wereperformed by hydrolyzing the samples according to themethod of Liu and Chang (1971) and analyzing the hyd­rolysates on a Beckman Model 121 M amino acid ana­lyser.

Functional PropertiesSolubility of the protein isolates was determined by

dispersing the isolates in distilled water, stirring at roomtemperature for 20 min, and then adjusting the pH valuesbetween 1.5 and 10.0. The samples were then centrifugedat 10,000 x g for 30 min and the supematant analyzed fornitrogen by the microKjeldahl method.

Emulsifying activity index (EAI) was determined bythe Pearce and Kinsella (1978) turbidimetric method andwater hydration capacity (WHC) was determined accord­ing to Quinn and Paton (1979). The procedure ofLin et al.(1974) was used to determine fat binding capacity (FBC)and the foaming properties were assessed by the proce­dure of Yatsumatsu et al. (1972). Surface (So) and ex­posed (Se) hydrophobicities were determined according tothe methods of Kato and Nakai (1980) and Townsend(1982), respectively.

Results and DiscussionYields and Chemical Compositions

Table 1 presents the yields and chemical compositionsof the two types of protein isolates from Hinoat andSentinal groats. SI constituted only 5-6% by weight of thegroats while AI made up about 12-13%. Both isolates hada protein content of over 90% using a conversion factor of5.80. The yield of Kjeldahl nitrogen was much higher inAI (over 60%) than SI (25%). The AS fraction from thealkaline extracts, constituting about 7.5 % of the groats byweight, had substantially less protein (ca 25%) than AIand represented about 10% of the total nitrogen. AlthoughHinoat groats had higher protein content than Sentinel, theyield of nitrogen in the respective isolates was about thesame. All the oat isolates were low in fat, ash and car­bohydrate. AS, on the other hand, had about 10% ash and60% carbohydrate.

Amino Acid CompositionTable 2 shows the amino acid composition of the

protein isolates from the two cultivars along with theamino acid profiles of the defatted groats. Compared tothe FAO/WHO (1973) recommendations, lysine is thelimiting amino acid in both SI and AI, with AI havinghigher aromatic and sulphur containing amino acids than

SI. The total essential amino acid content of AI was about40 g/16 g N; higher than that of the groats and the FAOrecommended level (35 g/16 g N), and considerablyhigher than that of SI (33 g/16 g N).

Functional PropertiesThe pH solubility curves of protein isolates from Sen­

tinel groats are shown in Figure 1. The curves of theHinoat isolates were not significantly different from theSentinel samples, with both AI and SI showing bellshaped curves, with minimum solubilities around pH 6and pH 5 for SI and AI, respectively. SI had highersolubility at acid pH than AI, while AI had significantlyhigher solubility than SI at alkaline pH, particularly at pHvalues between 7 and 9.

Table 3 summarizes the results of some of the func­tional properties studied for the oat protein isolates. Vitalgluten (Industrial Grain Products, Montreal, Quebec) andsoy protein isolate (Supro 610, Ralston Purina Co., St.Louis, MO), two plant proteins widely used in foods,were also included for comparison. Results on EAI deter­mination (Table 3) show that SI had a much lower EAIthan AI. The Sentinel isolates had slightly higher EAI thanthe Hinoat isolates. The AS fraction had considerablyhigher EAI than AI. When compared to gluten and soyisolates, the oat isolates, particularly SI, had lower emul­sifying activity.

EAI of the oat isolates were also determined at variouspH values (Figure 2). The pH EAI curves of both SI andAI resembled the pH solubility curves with minimumemulsifying activity between pH 4-6. However, the dif­ference between the highest and lowest EAI was not asmarked as the difference in solubility.

Both SI and AI had considerably lower WHC than soyisolate, but was comparable to gluten. AS, in contrast,had a fairly high WHC. The FBC of the oat isolates wasabout the same as soy isolate and considerably higher thangluten; AS again having a much higher FBC than theisolates (Table 3).

Except for SI from Hinoat, which had a low foamabil­ity, the oat isolates had a foamability equal to or higherthan that of the other two plant proteins; AS also havingfairly good foamability (Table 3). The foam stability ofsamples was determined at 30 and 60 min after foamingand all oat isolates had good foam stability when com­pared to gluten and soy isolates, with the exception of AS,which was poor in this regard.

The foamability and foam stability of the oat isolateswere also determined at various pH values. The pH

Table 1. Yields and chemical composition of oat protein isolates (% dry basis) I.

HinoatSalt isolate (SI)Alkaline isolate (AI)Alkaline supematant (AS)

SentinelSalt isolate (SI)Alkaline isolate (AI)Alkaline supemantant (AS)

I Average of duplicate determinations.2Percentage by weight of defatted groats.

202 / Ma

6.113.47.5

5.111.97.5

Protein Yield of Fat Ash Carbohydrate(%) Protein (%) (%) (%) (%)

98.9 26.2 0.8 0.2 0.195.7 65.9 1.3 1.0 0.322.8 8.9 1.0 11.4 59.6

95.9 24.8 1.0 0.3 0.190.8 67.2 2.3 1.2 0.224.7 10.0 0.9 10.6 58.2

J. Inst. Can. Sci. Technol. Aliment. Vol. 16, No. 3, 1983

Table 2. Amino acid composition of oat protein isolates (g/16 gN)'.

Hinoat Sentinel

Salt Alkaline Salt Alkaline

Amino acid Groat isolate isolate Groat isolate isolate

Lysine 3.4 3.3 3.8 4.3 3.2 4.0

Histidine 2.2 2.6 2.5 2.3 2.3 2.6

Agrinine 6.4 8.9 8.2 6.3 7.2 8.2

Aspartic acid 7.8 9.6 8.7 8.3 8.8 8.6

Threonine 3.0 3.4 3.6 3.3 3.1 3.6

Serine 4.4 5.0 5.0 4.5 4.8 5.2

Glutamic acid 19.8 20.4 23.5 20.7 18.0 24.8

Proline 4.7 4.3 5.4 5.3 4.0 5.9

Glycine 4.2 4.3 4.3 4.9 4.0 4.4

Alanine 4.2 4.1 4.6 4.9 4.0 4.9

Valine 5.0 4.3 4.9 5.2 3.8 5.2

Cystine 1.8 0.9 1.5 2.3 0.7 1.7Methionine 1.2 0.9 1.8 1.2 1.3 2.1

Isoleucine 3.7 3.6 3.8 4.0 3.6 3.8Luecine 7.3 7.2 8.6 7.8 6.9 9.1Tyrosine 3.3 4.3 4.8 3.3 4.2 4.6Phenylalanine 6.1 5.9 6.7 6.3 5.7 6.3

Total essential 34.8 33.8 39.4 35.7 32.5 40.5

IAverage of duplicate determinations.2Values taken from FAO/WHO (1973). Energy and protein requirements.

FAOScoringPattem2

5.5

4.0

5.03.53.54.07.06.06.0

35.0

10.59.07.56.04.53.01.5

50

60

3C, D). The curves showed a drop in foamability at pH 6with the foam stability of AI increasing with a rise in pH(Figures 3C, D).

The So and Se hydrophobicities of the oat isolates werealso determined (Table 3), AI having a higher So than SI,with SI from Hinoat having an exceptionally low So value.When heated in the presence of 1.5% sodium dodecylsulphate, the hydrophobicity (Se) of all isolates increasedmarkedly to a common value. Gluten and soy isolates alsohad Se values comparable to the oat isolates.

Preliminary experiments had shown that the yield ofprotein in AI was increased progressively with increase inalkali concentration, and no optimal pH was observed asreported previously (Wu et al., 1977). Although higher

2 3 4 5 6 7 8 9 10 11o

70

60w..Jl:ll:l..J

50 400

'"Z"#. -..

40 '1 30-'""'

30

20

20

10

10

100

90

80

foamability curves for SI followed the shape of the solu­bility curves with minimum foamability occurring be­tween pH 4.5 and 6.0 (Figures 3A, B), this parameterdecreasing again at pH higher than 7.5, even thoughsolubility was increased. The foam stability ofSI was verylow at acid pH and increased to a maximum at pH 7.5(Figures 3A, B). For AI, the foamability was low at acidpH and increased gradually with increase in pH (Figures

pH

pH

Fig. I. Nitrogen solubility curve of oat protein isolates from Sentinelgroats (A-SI; e-AI).

Fig. 2. EAI of oat protein isolates at various pH 'alues ( O-AI fromHinoat; e-AI from Sentinel; D-SI from Hinoat; A-SI fromSentinel).

Can. Inst. Food Sci. Technol. J. Vol. 16. No. 3. 1983 Ma /203

Table 3. Functional properties of oat protein isolates. gluten and soy isolate].

EAI WHC FBC Foamability Foam stability (%) So Se(m2/g) (mUg) (mUg) (mL)2 30 min 60 min

HinoatSalt isolate 10.2 0.9 1.6 25 18 17 20 980Alkaline isolate 23.2 0.8 1.4 76 50 45 240 1010Alkaline supemantant 56.2 3.0 3.9 63 12 10 nd3 nd

SentinelSalt isolate 14.6 0.8 1.5 65 40 38 85 915Alkaline isolate 30.6 0.8 1.8 80 52 50 269 1120Alkaline supemantant 48.6 3.1 4.2 72 10 9 nd ndGluten 49.4 1.0 0.9 50 25 10 75 1080Soy isolate 35.0 2.5 1.8 75 52 30 95 900

]Average of duplicate determinations.2Yolume of protein solution = 50 mL.3Not determined.

pH

Fig. 3. Foamability and foam stability of oat protein isolates at variouspH values (e·foamability: a·foam stability: A: SI from Hinoat:B: SI from Sentinel: C: AI from Hinoat: 0: AI from Sentinel).

yield can be obtained by increasing pH, at values greaterthan 10, the slurry became viscous and darkened. A pH of9.5 was therefore chosen and the resulting isolates had alight brown colour. A yield of 53% was reported by Wu etal., (1977) for the preparation of protein isolates fromhexane defatted Garland oat flour by alkali extraction.The yield obtained for Hinoat and Sentinel groats wasconsiderably higher (66-67%), which could be due to ahigher solid:solvent ratio (1 :6) used by the other workers.Using a conversion factor of 6.25, Wu et al., (1977)reported a protein content of 94-103% in the oat isolates,slightly higher than the present results (91-96%), based ona conversion factor of 5.8.

For SI, 0.5 M CaClzwas a more effective solvent than1.0 M NaCI. The yield of protein was affected slightly bythe salt concentration and an ionic strength of 1.0 wasfound to be the optimum for protein extraction, yielding acolourless extract.

Arntfield and Murray (1981) prepared fababean pro-

tein isolates by both salt and alkaline extractions andfound both the temperature of denuration and thermaltransition decreased with increases in extraction pH, sug­gesting protein denaturation. For oat isolates prepared atpH 9.5, there may be some denaturation of the proteins.However, alkaline extraction gave a much higher yieldthan salt extraction which makes the salt extraction econo­mically less attractive. The difference in the protein yieldbetween the two processes could be due to the fact that saltonly extracted globulins, while alkali extracted both glo­bulins and other Osborne proteins from oats (Ma et al.,1981). Although globulins are the major soluble proteinfraction in oats (Wu et al., 1972; Peterson and Smith,1976), the other Osborne fractions made up a signfiicantportion of the proteins.

The essential amino acid profiles of AI were similar tothose reported in the isolates prepared from other oatvarieties by alkaline extraction (Wu et al., 1977). Acomparison of the amino acid compositions of the twoisolates indicates that AI had a considerably better essen­tial amino acid profile than SI. Apart from lysine, whichwas limiting in both isolates, SI was also limited inthreonine and valine.

The AI had a pH solubility pattern which closelyresembled the isolate prepared from hexane defatted Daloat groats (Wu et al., 1977) and was not much differentfrom the SI. At pH 9.5 both isolates were over 90%soluble, indicating that the conditions employed for pre­paring AI can lead to substantial solubilization of thesalt-soluble proteins.

AI had a much higher EAI than SI and this could bedue to the higher solubility of AI at ·pH 7.5, the pH atwhich EAI were determined. This fact may also explainthe high EAI observed in AS which contained proteinssoluble at neutral pH. The relationship between solubilityand emulsifying activity is clearly illustrated in Figure 2and these results suggest the dependence on soluble pro­teins for emulsification, as has been reported for cotton­seed proteins (Cherry et al., 1979).

In contrast to emulsifying activity, all oat isolates hadsimilar WHC and FBe. AS had a much higher WHCwhich could be due to high fibre content in this fraction(Lapsley, 1980). The FBC of AS was also markedlyhigher than the isolates which may be attributed to a muchlower bulk density in this fraction, leading to substantialentrapment of oil.

BA

c

o 1.5 3.0 4.5 6.0 7.5 9.0 10.5 0 1.5 3.0 4.5 6.0 7.5 9.0 10.5

90

40

50

80

70

60

20

30

10

70

20

30

10

40

80

60

50

204/ Ma J. Inst. Can. Sci. Technol. Aliment. Vo!. 16, No. 3. 1983

Ma / 205

The foaming properties of the oat protein isolatescompared favourably with the other two plant proteins,except for SI from Hinoat. The relationships betweenfoaming properties and pH in the oat isolates did notexactly follow the pH solubility curves (e.g., the foama­bility and foam stability of AI were low at acid pH,although the protein solubility was fairly high). This wasin contrast to oilseed proteins, in which the pH foamingproperties relationship closely follows that of the proteinsolubility (Cherry et al., 1979). The results show thatfoaming properties of oat proteins do not depend entirelyon the quantity of soluble proteins. No qualitative analy­ses (e. g., gel electrophoresis) were made on the oat pro­teins extracted at various pH levels, and it was not knownwhether the difference in foaming properties was attri­buted to specific type(s) of proteins solubilized at a par­ticular pH.

Hydrophobicity has been shown to have great influ­ence on protein functionality (Voutsinas, 1982). In thisstudy, So was found to differ considerably between thetwo types of isolates and between the two oat varieties,while Se remained fairly constant. The higher So values ofAI could be due to some degree of denaturation or unfold­ing of the protein molecules. It has been demonstrated thatproteins having similar solubilities have higher EAI if Sois higher (Voutsinas, 1982). A good correlation has alsobeen demonstrated between Se and foaming properties(Townsend, 1982). In the present study, however, Soseems to correlate better than Se with foamability andfoam stability of the SI.

Protein concentrates had been prepared from Hinoatand Sentinel groats by alkaline extraction at pH 9.5 (Ma etal., 1981). The concentrates were found to have EAI,FBC and WHC intermediate between AS and AI. In thepreparation of oat concentrates, the neutralized extractswere freeze-dried, without centrifugation to separate ASand AI. The AS, though a small fraction, would contri­bute to the overall functional performance of the proteinconcentrate.

The present data indicate that protein isolates can beprepared from oats by salt and alkaline extraction.Although salt extraction was a milder procedure thanalkaline extraction, thus less liable to denaturation, itsyield was much lower. The alkaline isolates had a betteramino acid profile and were functionally equal to or betterthan the salt-soluble isolates. The alkaline procedure alsoproduces an AS fraction which has excellent functionalityand hence, alkaline extraction at pH around 9.5 seems tobe the more effective procedure to produce protein iso­lates from oats. Although the oat isolates had functionalproperties comparable to gluten and soy isolate, a know­ledge of the full potential of oat protein isolates as foodingredient requires further assessment in a variety of foodsystems.

Acknowled~ementThe technical assistance of A. Boisvert and G. Khan­

zada is acknowledged.

References

AACC, 1971. Approved Methods. American Association of CerealChemists, St. Paul, MN.

Amtfield, S.D. and Murray, E.D. 1981. The influence of processing

Can. Inst. Food Sci. Technol. J. Vo!. 16, No. 3, 1983

parameters on food protein functionality. I. Differential scan­ning calorimetry as an indicator of protein denaturation. Can.Inst. Food Sci. Technol. J. 14:289.

Bell, A., Boocock, J.R.B. and Oughton, R.W. 1978. Extraction ofprotein food values from oats. U.S. patent 4,089,848.

Cherry, J.P., McWatters, K.H. and Beuchat, L.R. 1979. Oilseed pro­tein properties related to functionality in emulsions and foams.ACS Symp. Ser. 92: 1.

Cluskey, J.E., Wu, Y.V., Wall, J.S. and Inglett, G.E. 1973. Oatprotein concentrates from a wet-milling process: Preparation.Cereal Chem. 50:475.

Cluskey, J.E., Wu, Y.V. and Wall, J.S. 1978. Density separation ofprotein from oat flour in nonaqueous solvents. J. Food Sci.43:785.

Concon, J.M. and Soltess, D. 1973. Rapid micro-Kjeldahl digestion ofcereal grains and other biological materials. Anal. Biochem.53:35.

Dubois, M., Gilles, K.A., Hamilton, J.K., Rebers, P.A. and Smith, F.1956. Colorimetric method for determination of sugars andrelated substances. Anal. Chem. 28:350.

FAO/WHO. 1073. Energy and protein requirements. WHO Tech. Rep.Ser. #522.

Hischke, H.H., Jr., Potter, G.C. and Graham, W.R., Jr. 1968. Nutritivevalue of oat proteins. I. Varietal differences as measured byamino acid analysis and rat growth responses. Cereal Chem.45:374.

Kato, A. and Nakai, S. 1980. Hydrophobicity determined by a fluore­scence probe method and its correlation with surface propertiesof proteins. Biochem. Biophys. Acta 624:13.

Lapsley, K. G. 1980. Some physico-chemical characteristics of dietaryfiber. M.Sc. Thesis. University of British Columbia, Vancou­ver, BC.

Lin, M.J., Humbert, E.S. and Sosulski, F.W. 1974. Certain functionalproperties of sunflower meal products. J. Food Sci. 39:368.

Liu, T.-Y. and Chang, Y.H. 1971. Hydrolysis of proteins with p­toluenesulfonic acid. Determination of tryptophan. J. BioI.Chem. 246:2842.

Ma, C.-Y., Harwalkar, V. and Paton, D. 1981. Extraction and charac­terization of protein concentrates from high-protein oats. Am.Assoc. Cereal Chem. 66th Annual Meeting (Abstract).

Murray, E.D., Myers, C.D. and Barker, L.D. 1978. Protein product andprocess for preparing same. Canadian patent 1,028,552.

Murray, E.D., Mysers, C.E., Barker, L.D. and Maurice, T.J. 1981.Functional attributes of proteins. A noncovalent approach toprocessing and utilizing proteins. In: Utilization of Protein Re­sources. D.W. Stanley, E.D. Murray and D.H. Lees (Eds.). p.158. Food and Nutrition Press, Westport, CT.

Pearce, K.N. and Kinsella, J.E. 1978. Emulsifying properties of pro­teins: Evaluation of a turbidimetric technique. J. Agric. FoodChem. 26:716.

Peterson, D.M. and Smith, D. 1976. Changes in nitrogen and carbohy­drate fractions in developing oat groats. Crop Sci. 16:67.

Quinn, J.R. and Paton, D. 1979. A practical measurement of waterhydration capacity of protein materials. Cereal Chem. 56:38.

Tkachuk, R. 1969. Nitrogen-to-protein conversion factors for cerealsand oilseed meals. Cereal Chem. 46:419.

Townsend, A. 1982. Relationship between physiocochemical propertiesand their foaming characteristics. Ph.D. Thesis. University ofBritish Columbia, Vancouver, BC.

Voutsinas, L.P. 1982. Studies on the hydrophobicity of proteins andenzymes. Ph.D. Thesis. University of British Columbia, Van­couver, BC.

Wu, Y. V., Sexson, K.R., Cavins, J.F. and Inglett, G.E. 1972. Oats andtheir dry-milled fractions:protein isolation and properties of fourvarieties. J. Agric. Food Chem. 20:757.

Wu, Y.V. and Stringfellow, A.C. 1973. Protein concentrates from oatflours by air classification of normal and high-protein varieties.Cereal Chem. 50:489.

Wu, Y.V., Sexon, K.R., Cluskey, I.E. and Inglett, G.E. 1977. Proteinisolate from high-protein oats: Preparation, composition andproperties. J. Food Sci. 42:1383.

Yatsumatsu, K., Sawada, K., Wada, T. and Ishu, K. 1972. Utilizationof soybean products in fish paste products. Agric. Bioi. Chem.36:737.

Youngs, V.L. 1974. Extraction of a high-protein layer from oat groatbran and flour. J. Food Sci. 39:1045.

Accepted December 2, 1982