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Nutritive Value of Meat Substitute Prepared from Brewers' Yeast and Isolated Soy Protein
Nutritive Value of Meat Substitute Prepared from Brewers' and Isolated Soy Protein
Yeas~
B. K. Dwivedi* and D. L. Gibson Department of Dairy and Food Science University of Saskatchewan, Saskatoon and
J. M. Bell Department of Animal Science University of Saskatchewan, Saskatoon
Abstract Two experiments were conducted with mice to evaluate the protein quality of a meat substitute. In the growth test studies, weight gains of mice on meat substitute were equal to weight gains of mice on soy protein isolate. However, the weight gains were slightly lower than 'Ilormal because of the inadequate amounts of methionine and cystine in the meat substitute and isolated soy protein rations. In the protein digestibility studies, it was observed that meat substitute proteins are higWy digestible. The true digestibility of meat substitute was 92% compared to whole egg at 95.5%. In the protein quality determinations it was found that average weight gains of mice, apparernt and true biological value and protein efficiency ratio (PER) for meat substitute were considerably less when compared to whole egg. When meat substitute was fortified with 1.0% methionine, these values were quite cOIll[larable to whole egg.
Resume Deux experiences avec des souris ont servi a revaluation proteique d'une simili-viande. Dans les etudes de croissance, les gains en poids des souris ont ete les memes avec la simili-viande et avec la proteine de soja. Ils ont ete legerement inferieurs a la normale a cause des teneurs inadequates en methionine et en cystine dans les deux types de ration. Dans les etudes de digestibilite, on a observe que les proteines de simili-viande sont fortement digestibles. La digestibilite vraie de la simili-viande a ete 92% par rapport a celIe de I'oeuf entier qui est 95.5%. Les determinations de la qualite protl~ique ont mis en evidence que les gains en poids moyens des souris, les valeurs biologiques aPIParente et vraie et Ie rapport d'efficacite proteique (PER) ont ete considerablement inferieurs avec la simili-viande qu'avec I'oeuf entier. En fortifiant la simili-viande avec 1% de methionine, ces valeurs ont ete avantageusement comparees a I'oeuf entier.
Introduction ~imu~ated meat products were successfully prepared m th.lS Department from processed brewers' yeast, soy protem and other vegetable ingredients (Gibson and Dwivedi, 1970). These products compared favorably to the respective natural meat products in flavor texture and palatability. ' All the ingredients used in the development of these meat analogs were of food grade standards and possessed good nutritional quality; brewers' yeast used as the base material, is widely recognized as a good source of proteins of high biological value and of other nutrients such as phosphorus and vitamin-B complex.. Harris et al. (1951) reported on the basis of repletIOn values for protein-deficient adult male rats th~t yeast possessed 50 to 85% of the food value of casem. When supplemented with methionine however, the yeast gave repletion values equival~nt to 'Present address: Del?artment of Food Science & Technology University of Nebraska, Lincoln, Neoraska 68503. ]
..,.)
casein. These findings confirm the earlier work of Macrae et al. (1942), Klose et al. (1945) and Cannon (1948). Isolated soy protein, another good quality vegetable protein, used in the preparation of meat analogs has been reported to give a PER value of 2.20 (Hackler et al.) 1963). This value is reasonably good when compared with other good quality animal 01' vegetable proteins. This study was undertaken to determine the overall nutritive value of one of the meat substitutes (simulated meat balls). Weanling mice were used in growth tests to evaluate protein quality having been found satisfactory as test animals in earlier work (Bell and Youngs, 1970). Since brewers' yeast and isolated soy protein are short in methionine the experiment was designed to find the effect of methionine addition on the protein quality of meat substitute.
Experimental procedure Two experiments were carried out on mice fol' evaluating the nutritive value of simulated meat balls. Growth test studies were conducted to determine the effect of these pl"oducts, when mixed with other cereal foods commonly used in the human diet, on the growth of weanling mice. Protein quality evaluation was carried out to determine the biological value of the proteins present in the meat substitute. 'l'he weanling male mice used in the experiments were derived from Carworth Farms No.1 strain. 'l'he mice weighed between 9.5 and 12.0 g and were individually housed in wire bottomed cages, with collection pans in a metal battery. The environmental temperature of the room was maintained at 24± 1°0. Food and water were provided ad libituJn and replenished every second day during the 14-day test. Growth test The experiment was conducted with 5 levels - 0, 25, 50, 75 and 100% of dietary proteins derived from meat substitute. The protein content in all the rations was maintained at 18%. The control protein was a soy protein isolate. The meat substitute (Table 1), filler material (Table 2) and protein-free basal mixture (Table 3) accounted for 90.5% of the weight of the final diet (Table 3). The remaining 9.5% consisted of 5% vitamin mixture and 4.5% mineral mixture (Table 3). At the end of the experiment, individual mice were weighed and their weight gains and feed intakes were recorded. Protein quality evaluation The experiment consisted of 3 levels and 2 sources of protein. The levels of protein were 8, 11 and 14% Can. Inst. Food Sci. Techno!. J. Vo!. 5, No.3, 1972
f the ration calculated on a dry matter basis. '['he ~wo protein sources were meat su~stitute an.d whole A fourth level of meat substItute was lIlcluded eg~taining 13% protein from meat replacer and 1% COethionine. There were three replicates of each ration. m The protein sources and protein-free basal mixture accounted for 85.5% of the weight of the final diet (Table 4). The remaining 14.5% c?nsisted ~f 5% vitamin mixture (Table 3), 4.5% mmeral mIxture (Table 3) and G% lard. At the end of the experiment, the feces from the three mice on each diet were collected and analyzed. The digestibility coefficients of proteins were obtained for each diet by the use of chromic oxide indicator technique. Chromic oxide in the feces was determined by a modification of the Bolin et al. (1952) method using perchloric acid for organic matter destruction. Crude protein in feces and mouse carcass was determined by the Kjeldahl method. Determinations of the body compositions of the mice were carried out by a modified Swedish tube method (Troeng, 1955). The apparent and true protein digestibilities were calculated with the formulae described by Maynard and Loosli (1962). Protein efficiency ratio, apparent and true biological values for meat substitute and whole egg were determined using the criteria discussed by 'Maynard and Loosli (1962). The endogenous urinary nitrogen excretion was determined by Brody's formula (1945): EN 146 WO.72 where EN Endogenous urinary nitrogen in lIIg/ day W A.verage of the initial and final weight of mouse in Kg. EN was then multiplied by 14 to obtain EN for 14 days. The nitrogen gained by the mouse was calculated by subtracting 2.64% of the initial weight of the mouse, which represents the amount of nitrogen in a weanling mouse, from the amount of nitrogen in the mOUse at the end of the test. The nitrogen gained was then substracted from the true digestible nitrogen intake. '['he difference was taken to represent the amount of nitr,ogen lost through urine. No attempt was made to calculate the amount of nitrogen lost through hair or skin sloughing.
Results and Discussion Growth test The average weight gain and feed intake of mice for each ration are recorded in Table 5. From these data average weight gainjg protein intake for indio vidual rations were calculated, and it was observed Table 1.
Table 2.
Composition of filler material. %*
Food stuff
10.0 10.0 10.0 20.0 10.0 20.0 10.0 5.0 5.0
Cane sugar Oatmeal Macaroni Wheat flour Rice flour Potato flakes Com flour Com flakes Shredded wheat "Dry matter basis
that weight gains did not differ significantly for different levels of meat substitute (P > .05); however, the weight gains were significantly different among replicates (P < .05). The feed intake also did not show any significant variation (P > .05) for different levels of meat substitute and for replicates. These studies show that meat substitute and soy protein isolate have the same effect on the growth of weanling mice; however, the weight gains were lower than normal, perhaps due to the inadequate amounts of methionine and cystine in the meat substitute and soy protein isolate rations.
Protein quality evaluation The apparent and true protein digestibility coefficents of meat substitute and whole egg are given in Table 6. It was observed that apparent and true protein digestibility of whole egg, meat substitute and meat substitute fortified with methionine were not significantly different (P > .05). The values for weight gains per 14 days, PER and biological value (apparent and true) are given in Table 7. Weight gains, PER and biological values for meat substitute proteins were observed to be inferior (P < .05) when compared to whole egg proteins, except in the case of methionine fortified rations in which these values were not significantly different (P > .05). This confirms that lower weight gains of mice in the growth test were due to the inadequacy of methionine. '['he slight differences observed in the biological value and PER of meat SUbstitute proteins fortified with methionine when compared to whole egg proteins may be explained on the basis that the total' nitrogen of meat substitute, a maj'Ol' portion of which comes from brewers' yeast, is not in the form of protein alone, but about 6% of it is accounted for by purine and pyrimidine compounds (Thorne, 1957). If this nitrogen is considered, the corrected protein content of the methionine added ration comes to Table 4.
Composition of diets for protein quality test. ----
Feed-stuff
Crude protein
Basal
(%)
Proximate composition of meat substitute. %
Dry matter Crude protein (N x 6.25) Ash Fat Nitrogen free extract and crude fibre J. lnst. Can. Sci. Technol. Aliment. Vol. 5. No 3, 1972
--~~~-
Protein Cellu- Methionine source lose
41.80 14.30 1.66 17.20 8.64
Meat substitute
Whole egg (defatted)
8.3 11.0 13.6 13.6 7.9
64.0 58.5 53.1 53.9 69.3
16.5 22.0 27.4 25.6 11.2
5.0 5.0 5.0 5.0 5.0
10.6 13.2
65.5 61.8
15.0 18.7
5.0 5.0
1.0
156
Table 3.
Compositions of diets for growth test.
Constituents
o 0.0 46.0 20.0 24.5 5.0 4.5
Meat substitute Soy protein isolate mix 1 Filler material Protein-free basal mixture 2 Vitamin mixture 3 Mineral mixture 4 1 2
3
4
Levels of meat substitute % 75 50 25 23.0 23.0 20.0 24.5 5.0 4.5
11.5 34.5 20.0 24.5 5.0 4.5
100 46.0 0.0 20.0
34.5 11.5 20.0 24.5 5.0 4.5
24.5
5.0 4.5
Soy protein isolate mix: soy protein isolate, 36.5%; Crisco fat, 36.0%; stal1ch, 27.5%. Protein-free basal mixture: corn starch, 50%; cerelose, 30%; sucrose, 15%; cellulose, 5%. Vitamin mixture: thiamine HC1, 0.01%; riboflavin, 0.02%; pantothenic acid (as calcium pentothenate), 0.10%; niacin, 0.1%; biotin, 0.002%; pyridoxine HC1, 0.01%; vitamin B12 (1 % triturate), 0.05%; folic acid, 0.005%; inositol, 0.004%; choline chloride, 8%; vitamin A (325,000 I.U'/g) , 0.03%; vitamin D (500,000 I.U'/g), 0.0125%; vitamin E (125,000 I.U'/g), 1%; vitamin K (as menadione), 0.4%; starch, 90.5%. Mineral mixture: NaCI (iodized), 4%; CaHP04 .2H zO, 68.7%; KHC03, 13.6%; MgO, 1.8%; MnS04.H zO, 0.3%; CuS04.5HzO, 0.1%; FeS04.2HzO, 0.3%; ZnO, 0.1%; CrZ03, 11.1%.
Table 5.
Average weight gain and feed intake of mice in growth test studies.
Levels of meat substitute (%)
Soy protein in diets (%)
0 25 50 75 100
15.6 13.6 11.6 9.6 7.6
Feed intake
Weight gain (g) 8.75 7.38 7.73 6.90 7.25
± ± ± ± ±
Weight gain/g Protein intake
(g) 1.61" 1.50 0.50 0.83 0.88
47.78 44.21 44.68 46.66 47.35
± ± ± ± ±
4.07" 2.75 1.01 1.84 3.84
0.976 0.890 0.961 0.815 0.855
"S.E. of mean.
Table 7.
A comparison of protein quality of meat substitute by several methods. Weight gain in 14 days
Dietary protein level (%)
Protein source
Whole egg (defatted) Meat substitute Meat substitute (1 % methionine added)
___Biological value Apparent True (%)
PER
(g)
7.9 10.6 13.2 8.3 11.0 13.6
9.74 9.52 9.83 4.01 3.75 6.55
13.6
9.50
± ±
1.30" 1.40 1.29 0.39 1.45 0.38
2.52 1.85 1.89 1.07 0.74 1.10
± ± ± ± ± ±
0.29" 0.39 0.20 0.03 0.24 0.15
55.0 42.0 39.3 26.8 17.5 25.4
67.2(100)"" 53.0(00) 50.6( 100) 40.0(59.6) 28.0(52.8) 36.6(72.2)
±
0.68
1.70
±
0.15
36.3
47.4(93.7)
± ± ±
-1-
" S.E. of mean. ""Figures in brackets show the true B.V. of protein source, taking whole egg as standard, i.e. 100% B.V.
Table 6.
Apparent and true protein digestibility of meat substitute and whole egg.
Feed-stuff Meat Meat substitute (1% methionine added) Whole egg (defatted) "S.E. of mean.
157
Digestibility Apparent protein True protein (%) 86.97
-1-
0.21"
91.97
±
1.07"
85.79
±
1.18
89.60
±
0.96
89.84
±
1.07
95.50
±
1.39
12.8% (about 0.8% less than reported). The nutritional contribution of purine and pyrimidine COlllpounds is controversial. However, there are reports that addition :of yeast in a high protein diet caused increased elimination of uric acid but there was no increase in blood uric acid; on the other hand, addition of yeast in a low protein diet did not cause an increase in uric acid secretion (Still and Koch, 1928).
Conclusions Growth test and protein quality determinations indicate that meat substitute prepared from brewers' Can. lnst. Food Sci. Technoi. J. Vol. 5, No.3, 1972
rocessed yeast, isolated soy protein and other vegetible ingredients ~ave. excellent protein d~gestibility and fair.ly go~d blOlog.Ica~ value. "'Yhen. thIs product is fortifIed wIth metillomne, the bIOlogIcal value becomes comparable to that of whole egg or any good quality animal protein.
Acknowledgements Financial support from the Canada Department of Agriculture through an Extra Mural Research Grant for this investigation is gratefully acknowledged.
References Bell J. M. and Youngs, C. G. 1970. Studies on the nutritive value of pea protein concentrate. Can. J. Animal Sci., 50: 219. Bolin, D. W .. King, R. P. and Klosterman. E. W. 1952. A simplified method for determination of chromic oxide when used as index substance. Science, 116: 634. Brody, S. 1945. Bioenergetics and Growth. Reinhold Pub. Corp., New York.
J. lnst. Can. Sci. Techno!. Allment. Vol. 5, No 3, 1972
Cannon, P. R. 1948. Protein values of yeast. Yeast in feeding. Proc. Symposium Nov. 8-10. The Associates. Food and Container Inc., Chicago. Gibson, D. L. and DWivedl, B. K. 1970. Production of meat substitutes from spent brewers' yeast and soy protein. Can. Inst. Food Tech. J., 3': 113. Hackler, I. R., Hand, D. B., Steinkraus, K. H. and Van Buren, J. P. 1963. A comparison of the nutritional value of protein from several soybean fractions. J. Nutr., 30: 205. Harris, E. E., Hajney, G. J. and Johnson, M. C. 1951. Protein eValuation of yeast grown on wood hydrolysate. Ind. Eng. Chem., 43: 1593.
Owusu-Domfeh, K. 1967. Nutritive value of some Ghanaian feed stuffs. M.Sc. thesis. Dept. of Animal Sci., Unlv. of Sask., Saskatoon. Klose, A. A. and Fevold, H. L. 1945. Nutritional value of yeast protein to the rat and chick. J. Nutr., 29: 421. Macrae, T. F., El-sadr, M. M. and Seller, K. C. 1942. The nutritive value of yeast protein: Comparison of the supplementary values of yeast protein and casein for maize protein In the nutrition of pig. Blochem. J., 36: 460. Maynard, L. A. and Loosll, J. K. 1962. Animal Nutrition. McGrawHlll Book Co. Inc., New York. Still. E. U. and Koch, E. M. 1928. A study of the effect of the yeast upon metabolism. Am. J. Physiol., 85: 33. Thorne, R. S. W. 1957. Yeasts. Edited by W. Roman. Dr. W. Junk Publlshers. The Hague. Troeng, S. 1955. 011 determination of oil seed. Gravimetric routine method. J. Am. Oil Chem. Soc., 32: 124. Received Mar. 18, 1970.
158
Yeas~
B. K. Dwivedi* and D. L. Gibson Department of Dairy and Food Science University of Saskatchewan, Saskatoon and
J. M. Bell Department of Animal Science University of Saskatchewan, Saskatoon
Abstract Two experiments were conducted with mice to evaluate the protein quality of a meat substitute. In the growth test studies, weight gains of mice on meat substitute were equal to weight gains of mice on soy protein isolate. However, the weight gains were slightly lower than 'Ilormal because of the inadequate amounts of methionine and cystine in the meat substitute and isolated soy protein rations. In the protein digestibility studies, it was observed that meat substitute proteins are higWy digestible. The true digestibility of meat substitute was 92% compared to whole egg at 95.5%. In the protein quality determinations it was found that average weight gains of mice, apparernt and true biological value and protein efficiency ratio (PER) for meat substitute were considerably less when compared to whole egg. When meat substitute was fortified with 1.0% methionine, these values were quite cOIll[larable to whole egg.
Resume Deux experiences avec des souris ont servi a revaluation proteique d'une simili-viande. Dans les etudes de croissance, les gains en poids des souris ont ete les memes avec la simili-viande et avec la proteine de soja. Ils ont ete legerement inferieurs a la normale a cause des teneurs inadequates en methionine et en cystine dans les deux types de ration. Dans les etudes de digestibilite, on a observe que les proteines de simili-viande sont fortement digestibles. La digestibilite vraie de la simili-viande a ete 92% par rapport a celIe de I'oeuf entier qui est 95.5%. Les determinations de la qualite protl~ique ont mis en evidence que les gains en poids moyens des souris, les valeurs biologiques aPIParente et vraie et Ie rapport d'efficacite proteique (PER) ont ete considerablement inferieurs avec la simili-viande qu'avec I'oeuf entier. En fortifiant la simili-viande avec 1% de methionine, ces valeurs ont ete avantageusement comparees a I'oeuf entier.
Introduction ~imu~ated meat products were successfully prepared m th.lS Department from processed brewers' yeast, soy protem and other vegetable ingredients (Gibson and Dwivedi, 1970). These products compared favorably to the respective natural meat products in flavor texture and palatability. ' All the ingredients used in the development of these meat analogs were of food grade standards and possessed good nutritional quality; brewers' yeast used as the base material, is widely recognized as a good source of proteins of high biological value and of other nutrients such as phosphorus and vitamin-B complex.. Harris et al. (1951) reported on the basis of repletIOn values for protein-deficient adult male rats th~t yeast possessed 50 to 85% of the food value of casem. When supplemented with methionine however, the yeast gave repletion values equival~nt to 'Present address: Del?artment of Food Science & Technology University of Nebraska, Lincoln, Neoraska 68503. ]
..,.)
casein. These findings confirm the earlier work of Macrae et al. (1942), Klose et al. (1945) and Cannon (1948). Isolated soy protein, another good quality vegetable protein, used in the preparation of meat analogs has been reported to give a PER value of 2.20 (Hackler et al.) 1963). This value is reasonably good when compared with other good quality animal 01' vegetable proteins. This study was undertaken to determine the overall nutritive value of one of the meat substitutes (simulated meat balls). Weanling mice were used in growth tests to evaluate protein quality having been found satisfactory as test animals in earlier work (Bell and Youngs, 1970). Since brewers' yeast and isolated soy protein are short in methionine the experiment was designed to find the effect of methionine addition on the protein quality of meat substitute.
Experimental procedure Two experiments were carried out on mice fol' evaluating the nutritive value of simulated meat balls. Growth test studies were conducted to determine the effect of these pl"oducts, when mixed with other cereal foods commonly used in the human diet, on the growth of weanling mice. Protein quality evaluation was carried out to determine the biological value of the proteins present in the meat substitute. 'l'he weanling male mice used in the experiments were derived from Carworth Farms No.1 strain. 'l'he mice weighed between 9.5 and 12.0 g and were individually housed in wire bottomed cages, with collection pans in a metal battery. The environmental temperature of the room was maintained at 24± 1°0. Food and water were provided ad libituJn and replenished every second day during the 14-day test. Growth test The experiment was conducted with 5 levels - 0, 25, 50, 75 and 100% of dietary proteins derived from meat substitute. The protein content in all the rations was maintained at 18%. The control protein was a soy protein isolate. The meat substitute (Table 1), filler material (Table 2) and protein-free basal mixture (Table 3) accounted for 90.5% of the weight of the final diet (Table 3). The remaining 9.5% consisted of 5% vitamin mixture and 4.5% mineral mixture (Table 3). At the end of the experiment, individual mice were weighed and their weight gains and feed intakes were recorded. Protein quality evaluation The experiment consisted of 3 levels and 2 sources of protein. The levels of protein were 8, 11 and 14% Can. Inst. Food Sci. Techno!. J. Vo!. 5, No.3, 1972
f the ration calculated on a dry matter basis. '['he ~wo protein sources were meat su~stitute an.d whole A fourth level of meat substItute was lIlcluded eg~taining 13% protein from meat replacer and 1% COethionine. There were three replicates of each ration. m The protein sources and protein-free basal mixture accounted for 85.5% of the weight of the final diet (Table 4). The remaining 14.5% c?nsisted ~f 5% vitamin mixture (Table 3), 4.5% mmeral mIxture (Table 3) and G% lard. At the end of the experiment, the feces from the three mice on each diet were collected and analyzed. The digestibility coefficients of proteins were obtained for each diet by the use of chromic oxide indicator technique. Chromic oxide in the feces was determined by a modification of the Bolin et al. (1952) method using perchloric acid for organic matter destruction. Crude protein in feces and mouse carcass was determined by the Kjeldahl method. Determinations of the body compositions of the mice were carried out by a modified Swedish tube method (Troeng, 1955). The apparent and true protein digestibilities were calculated with the formulae described by Maynard and Loosli (1962). Protein efficiency ratio, apparent and true biological values for meat substitute and whole egg were determined using the criteria discussed by 'Maynard and Loosli (1962). The endogenous urinary nitrogen excretion was determined by Brody's formula (1945): EN 146 WO.72 where EN Endogenous urinary nitrogen in lIIg/ day W A.verage of the initial and final weight of mouse in Kg. EN was then multiplied by 14 to obtain EN for 14 days. The nitrogen gained by the mouse was calculated by subtracting 2.64% of the initial weight of the mouse, which represents the amount of nitrogen in a weanling mouse, from the amount of nitrogen in the mOUse at the end of the test. The nitrogen gained was then substracted from the true digestible nitrogen intake. '['he difference was taken to represent the amount of nitr,ogen lost through urine. No attempt was made to calculate the amount of nitrogen lost through hair or skin sloughing.
Results and Discussion Growth test The average weight gain and feed intake of mice for each ration are recorded in Table 5. From these data average weight gainjg protein intake for indio vidual rations were calculated, and it was observed Table 1.
Table 2.
Composition of filler material. %*
Food stuff
10.0 10.0 10.0 20.0 10.0 20.0 10.0 5.0 5.0
Cane sugar Oatmeal Macaroni Wheat flour Rice flour Potato flakes Com flour Com flakes Shredded wheat "Dry matter basis
that weight gains did not differ significantly for different levels of meat substitute (P > .05); however, the weight gains were significantly different among replicates (P < .05). The feed intake also did not show any significant variation (P > .05) for different levels of meat substitute and for replicates. These studies show that meat substitute and soy protein isolate have the same effect on the growth of weanling mice; however, the weight gains were lower than normal, perhaps due to the inadequate amounts of methionine and cystine in the meat substitute and soy protein isolate rations.
Protein quality evaluation The apparent and true protein digestibility coefficents of meat substitute and whole egg are given in Table 6. It was observed that apparent and true protein digestibility of whole egg, meat substitute and meat substitute fortified with methionine were not significantly different (P > .05). The values for weight gains per 14 days, PER and biological value (apparent and true) are given in Table 7. Weight gains, PER and biological values for meat substitute proteins were observed to be inferior (P < .05) when compared to whole egg proteins, except in the case of methionine fortified rations in which these values were not significantly different (P > .05). This confirms that lower weight gains of mice in the growth test were due to the inadequacy of methionine. '['he slight differences observed in the biological value and PER of meat SUbstitute proteins fortified with methionine when compared to whole egg proteins may be explained on the basis that the total' nitrogen of meat substitute, a maj'Ol' portion of which comes from brewers' yeast, is not in the form of protein alone, but about 6% of it is accounted for by purine and pyrimidine compounds (Thorne, 1957). If this nitrogen is considered, the corrected protein content of the methionine added ration comes to Table 4.
Composition of diets for protein quality test. ----
Feed-stuff
Crude protein
Basal
(%)
Proximate composition of meat substitute. %
Dry matter Crude protein (N x 6.25) Ash Fat Nitrogen free extract and crude fibre J. lnst. Can. Sci. Technol. Aliment. Vol. 5. No 3, 1972
--~~~-
Protein Cellu- Methionine source lose
41.80 14.30 1.66 17.20 8.64
Meat substitute
Whole egg (defatted)
8.3 11.0 13.6 13.6 7.9
64.0 58.5 53.1 53.9 69.3
16.5 22.0 27.4 25.6 11.2
5.0 5.0 5.0 5.0 5.0
10.6 13.2
65.5 61.8
15.0 18.7
5.0 5.0
1.0
156
Table 3.
Compositions of diets for growth test.
Constituents
o 0.0 46.0 20.0 24.5 5.0 4.5
Meat substitute Soy protein isolate mix 1 Filler material Protein-free basal mixture 2 Vitamin mixture 3 Mineral mixture 4 1 2
3
4
Levels of meat substitute % 75 50 25 23.0 23.0 20.0 24.5 5.0 4.5
11.5 34.5 20.0 24.5 5.0 4.5
100 46.0 0.0 20.0
34.5 11.5 20.0 24.5 5.0 4.5
24.5
5.0 4.5
Soy protein isolate mix: soy protein isolate, 36.5%; Crisco fat, 36.0%; stal1ch, 27.5%. Protein-free basal mixture: corn starch, 50%; cerelose, 30%; sucrose, 15%; cellulose, 5%. Vitamin mixture: thiamine HC1, 0.01%; riboflavin, 0.02%; pantothenic acid (as calcium pentothenate), 0.10%; niacin, 0.1%; biotin, 0.002%; pyridoxine HC1, 0.01%; vitamin B12 (1 % triturate), 0.05%; folic acid, 0.005%; inositol, 0.004%; choline chloride, 8%; vitamin A (325,000 I.U'/g) , 0.03%; vitamin D (500,000 I.U'/g), 0.0125%; vitamin E (125,000 I.U'/g), 1%; vitamin K (as menadione), 0.4%; starch, 90.5%. Mineral mixture: NaCI (iodized), 4%; CaHP04 .2H zO, 68.7%; KHC03, 13.6%; MgO, 1.8%; MnS04.H zO, 0.3%; CuS04.5HzO, 0.1%; FeS04.2HzO, 0.3%; ZnO, 0.1%; CrZ03, 11.1%.
Table 5.
Average weight gain and feed intake of mice in growth test studies.
Levels of meat substitute (%)
Soy protein in diets (%)
0 25 50 75 100
15.6 13.6 11.6 9.6 7.6
Feed intake
Weight gain (g) 8.75 7.38 7.73 6.90 7.25
± ± ± ± ±
Weight gain/g Protein intake
(g) 1.61" 1.50 0.50 0.83 0.88
47.78 44.21 44.68 46.66 47.35
± ± ± ± ±
4.07" 2.75 1.01 1.84 3.84
0.976 0.890 0.961 0.815 0.855
"S.E. of mean.
Table 7.
A comparison of protein quality of meat substitute by several methods. Weight gain in 14 days
Dietary protein level (%)
Protein source
Whole egg (defatted) Meat substitute Meat substitute (1 % methionine added)
___Biological value Apparent True (%)
PER
(g)
7.9 10.6 13.2 8.3 11.0 13.6
9.74 9.52 9.83 4.01 3.75 6.55
13.6
9.50
± ±
1.30" 1.40 1.29 0.39 1.45 0.38
2.52 1.85 1.89 1.07 0.74 1.10
± ± ± ± ± ±
0.29" 0.39 0.20 0.03 0.24 0.15
55.0 42.0 39.3 26.8 17.5 25.4
67.2(100)"" 53.0(00) 50.6( 100) 40.0(59.6) 28.0(52.8) 36.6(72.2)
±
0.68
1.70
±
0.15
36.3
47.4(93.7)
± ± ±
-1-
" S.E. of mean. ""Figures in brackets show the true B.V. of protein source, taking whole egg as standard, i.e. 100% B.V.
Table 6.
Apparent and true protein digestibility of meat substitute and whole egg.
Feed-stuff Meat Meat substitute (1% methionine added) Whole egg (defatted) "S.E. of mean.
157
Digestibility Apparent protein True protein (%) 86.97
-1-
0.21"
91.97
±
1.07"
85.79
±
1.18
89.60
±
0.96
89.84
±
1.07
95.50
±
1.39
12.8% (about 0.8% less than reported). The nutritional contribution of purine and pyrimidine COlllpounds is controversial. However, there are reports that addition :of yeast in a high protein diet caused increased elimination of uric acid but there was no increase in blood uric acid; on the other hand, addition of yeast in a low protein diet did not cause an increase in uric acid secretion (Still and Koch, 1928).
Conclusions Growth test and protein quality determinations indicate that meat substitute prepared from brewers' Can. lnst. Food Sci. Technoi. J. Vol. 5, No.3, 1972
rocessed yeast, isolated soy protein and other vegetible ingredients ~ave. excellent protein d~gestibility and fair.ly go~d blOlog.Ica~ value. "'Yhen. thIs product is fortifIed wIth metillomne, the bIOlogIcal value becomes comparable to that of whole egg or any good quality animal protein.
Acknowledgements Financial support from the Canada Department of Agriculture through an Extra Mural Research Grant for this investigation is gratefully acknowledged.
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Owusu-Domfeh, K. 1967. Nutritive value of some Ghanaian feed stuffs. M.Sc. thesis. Dept. of Animal Sci., Unlv. of Sask., Saskatoon. Klose, A. A. and Fevold, H. L. 1945. Nutritional value of yeast protein to the rat and chick. J. Nutr., 29: 421. Macrae, T. F., El-sadr, M. M. and Seller, K. C. 1942. The nutritive value of yeast protein: Comparison of the supplementary values of yeast protein and casein for maize protein In the nutrition of pig. Blochem. J., 36: 460. Maynard, L. A. and Loosll, J. K. 1962. Animal Nutrition. McGrawHlll Book Co. Inc., New York. Still. E. U. and Koch, E. M. 1928. A study of the effect of the yeast upon metabolism. Am. J. Physiol., 85: 33. Thorne, R. S. W. 1957. Yeasts. Edited by W. Roman. Dr. W. Junk Publlshers. The Hague. Troeng, S. 1955. 011 determination of oil seed. Gravimetric routine method. J. Am. Oil Chem. Soc., 32: 124. Received Mar. 18, 1970.
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