Nutritional evaluation of some varieties of Phaseolus vulgaris.

Abstract

274 SUMMARY Different varieties of common beans (P~zs~o~s Vzdgaris) differ significantly in their ability to support the growth of TriboZim castanet larvae. Raw beans were toxic. The toxic components could be removed by autoclaving, and partially by water extraction. The water and aqueous methanol (20% water) did extract different toxicants. Beans differed in their antinutrient contents. Varietal differences were observed in their amino acid profiles. Even after methionine supplementation, varietal differences in nutritive value of beans were observed that were not correlated to the color of the beans. The beans, in general, were deficient in methionine. For screening nutritional value, the growth of the tribolium larvae can be used for bioassay. The varietal differences in beans were also observed for supporting growth of Japanese quail. INTRODUCTION The bulk of our food is supplied by the following two plant families: Graminae or the grass family consisting of most of the cereal grains; and Leguminosae or the legume family consisting of most of the beans and pulses. The term legume refers to the seed or fruit of a pod-bearing plant that have nodules on the roots housing Rhizobium capable of meeting the nitrogen needs of the host plant by fixing atmospheric nitrogen. The Leguminosae family is one of the largest families of flowering plants. The subfamily Papilionodea can be subdivided on the basis of common usage into forage legumes and food-grain legumes. The food-grain legumes, rich in oil are called oilseeds and the ones low in oil are pulses or beans. There is some confusion in the classification of beans. A large number of beans have been classified% under the genus &lSex and some of these are from the new world and the others are from the old. According to a more recent suggestion, new world beans should belong to the genus Phaseolus and the old-world beans are better classified under the genus Vigna (Evans, 1979). The developing countries harvested 12,413,OOO metric tons of dry beans while the developed world harvested only 2,251,OOO metric tons in 1980. Beans have been aptly called the poor man's meat as these are the main source of protein in the develop$ng countries where, unfortunately, their cultivation is being replaced with that of cereals. The world grows more oilseeds than dry beans as is evident by a production of 83,480,OOO metric tons of soybeans during the same time. The bulk of the soybeans are fed to animals in the developed countries! The literature on nutritional value 'of Phaseohs VZ@~F~S has been reviewed by Tobin and Carpenter (19781, and on toxic proteins and amino Department of Avian Sciences, University of California, Davis, Ca 95616, U.S.A. 275 acids by Roy (1981). In general, raw beans (Phzseohs vzt~gds) contain many antinutrients and even toxic substances. For this reason, beans are poorly utilized by monogastric animals. The plant breeders tend to select varieties that are low in antinutrients. The antinutrients may be involved in protecting beans against insects and fungi (Gatehouse et al. Raw beans were growth depressing and often fatal for quail (JayneWilliams and Burgess 1974), chickens (Untawale and McGinnis 1979) and rats (Jaffe and Lette 1968); and caused acute gastroenteritis in humans (Noah et al. 1980; Bender and Reaidi 1982). 1 9 7 9 ) l The beans need heat processing to get rid of their antinutrient The heat-labile anti-nutrients are proteinous in nature and include lectins or hemagglutinins (Liener. 1962; Jaffe 1980; Pusztai a l . 1981; Bender and Reaidi 1982), and antienzymes and non-specific et protease inhibitors (Kakade et al. 1973; Jaffe, 1973, Whitaker and Feeny 1973; Liener and Kakade980). The overheating of beans is also deleterious as it causes a browning reaction and reduces the availability of lysine (Almas and Bender 1980; Antunes and Sgarbieri 1980) and certain other amino acids (Evans and Bauer 1978). Again, even the properly processed beans do not support the optimal growth of animals unless supplemented with methionine (Tobin and Carpenter 1978). Phytate also has some role in poor utilization of beans (Alli and Baker 1981). properties. the colored varieties, and the poor protein digestibility of colored White beans are reported to support the growth of rats better than beans was attributed to tannins and other polyphenols in the seed coat (Elias et al. 1979; Phillips et al. 1981). The beans orginating in the New World cannot be eaten safely by soaking and sprouting (Bender and Reaidi 1982) as is customarily done for mung beans (Khan and Ghafoor 1978) and soybeans in the Old World. We have attempted to screen the nutritional value of white and colored beans by an insect assay and find it useful in testing small sized samples and fractions. A further evaluation was done using Japane se quail. MATERIALS AND METHODS The beans of known varieties were cultivated at Davis for these studies. The proximate composition was determined by the procedures outlined in AOAC (1970). The amino acid profile of the samples was determined after acid hydrolysis by ion-exchange chromatography. Tryptophan was determined by the method of DeVries et al. (1980). Trypsin inhibitor activity was measured by the procedure of Kakade et al. (1974). The processing and fractionation procedures involved auto-claving, extractions with water or aqueous methanol (20% water) P freeze drying and heating: The larvae of an insect Tribdiwn castanezan were used for screening the nutritional value of beans and their fractions according to the - procedures described by Shariff et al. (1981) and Wyckoff et al. (1983a). Tribolium were maintained on a w= unbleached wheat flourdiet containing 10% brewers yeast in an incubator at 33 ? l�C and 70 ,+ 5% relative humidity. After placing about 500 adults on fresh diet, eggs were sieved out after 8 to 24 hours and placed on fresh diet. After 6 days, larvae were collected, and about 50 larvae were transferred to test diets for acclimatization for 2 days. The larvae were sieved again through silk screens and 10 larvae per triplicate were transferred to 276 2.5 x 5 cm glass vials each containing about 2 g of test diets and incubated for 6 more days before sieving out the larvae, counting and weighing them. The five varieties of beans, Dark Red Kidney (DRK), Light Red Kidney (LW), Sutter Pink (SP), Black Turtle Soup (BTS), and Small White (SW) were further evaluated for the growth of Japanese quail following the usual husbandry procedures. The body weights were determined and some of the tissues were also weighed. The statistical significance of the data was evaluated at PQ.05 using analysis of variance. RESULTS AND DISCUSSION Table 1. Proximate analysis, trypsin inhibitor (TI) activity, and amino acid profiles of raw beans (Wyckoff et al. 1983a) COMPOSITION AND AMINO ACID PROFILES: The data of proximate analysis, trypsin inhibitor activity and amino acid profiles of 5 beans are given in Table 1. The varietal differences are evidence from these data. 277 TESTING OF BEAN VARIETIES: Thirteen different varieties of raw beans, beans autoclaved at 1.266 kg/sq. cm (18 lb/sq. inch) and water extracted powdered beans were fed to tribolium larvae in a diet containing 35% bean powder, 5% brewers yeast and 65% corn starch. The results are presented in Table 2. Table 2. Average larval weight on diets containing raw, autoclaved or water extracted ground beans (Phaseohs vtczgaz%s), along with crude protein content of test samples.' (Shariff et al. 1981) The raw beans,' in general, significantly reduced the growth of larvae. The larvae developed better on the raw Red and Dark Red Kidney beans than on the other test samples. Some varieties caused more mortality than the others. Varietal differences were present even after the beans have been autoclaved as the growth of larve on Red Kidney, Chief and Dark Red .Kidney diets was as good as on the control diet. Relatively, the best and the worst raw beans still retained that ranking on autoclaving. The water extraction improved the residual beans, but the larval growth was less than on autoclaved beans. T. eastaneum could differentiate between nutritive value of different varieties of raw, autoclaved or water extracted beans. Similar observations had been reported with chickens (Reddy et al., 1980). The varietal differences may be due to amino acid profiles or presence of 278 some other heat stable toxicants including complex carbohydrates (Sathe 1981; Rogel and Vohra 1981). and Salunkhe TESTING OF BEAN FRACTIONS: Six different varieties of beans were subjected to the following treatments: autoclaving at 112OC for 30 minutes, extraction of ground beans (14 g) with distilled water (40 ml) or aqueous methanol (20% water) 3 times and with acetone before drying at room temperature. The extracts were freeze dried. The crude protein content of these fractions are given in Table 3. The protein content of the residue decreased after water extraction and increased after aqueous methanol extraction. Methanol extracts more of free sugars, and water extracts both sugars and albumins and globulins. Table 3. The effect of water and aqueous-methanol (20% water) extraction on the protein content of bean residues; and the dry matter of extracts. The test diets (Table 4) for tribolium assay contained- 16% protein and half of it was provided by the beans or their fraction. The results of feeding of these residual beans and dried extracts in stock diet to tribolium larve are given in Table 5. (Wyckoff et al. 1983). As expected, raw beans were significantly poorer than ztz claved beans in supporting larval growth. The larval growth was better on autoclaved Small White Auroa and Red Pinquito varieties than on Pinto UI-111, Pink Gloria or 7799, thus confirming varietal differences. A detailed fractionation of ground raw Black beans was carried out as described in Fig. 1. The numbers underneath each fraction indicate average larval growth, and the mortality is indicated in parenthesis. The average larval weights on the wheat-flour control was'2.71 mg and Mean Standard Error for the experiment was ,044. The larval growth was significantly improved by autoclaving the residue left after extraction with aqueous methanol but not by water. The heating of the freeze-dried water extract significantly improved the larval growth as compared to that on unheated water-extract. No significant improvement on heating was observed for methanol-extract. The two solvents can be used for extracting different antinutrients. As water extracts globulins and albumins, these were denatured on heating. Methanol extracts mostly free sugars and these are not influenced on heating and antinutrient - 279 properties were maintained. Table 4. Composition of the test diets (g 10-l g diet) Table 5. Mean larval weights on various beans and bean fractions 281 THE INFLUENCE OF COLOR ON NUTRITIVE VALUE OF BEANS: In a collaborative study, Dr. George F. Freytag of the Mayaguez Institute of the Tropical Agriculture, Puerto Rico prepared extracts from hand-dissected coats of white and colored beans. The extracts were added back to the extracted sample at equivalent or twice that amount and dried. The bioassay of these samples was done at Davis using tribolium larvae. The unpublished data are presented in Table 6. The data suggest that tribolium larvae respond to varietal differences in beans. However, the polyphenols as such were of less importance. We could not confirm the major role of color coat of beans in determining nutritive value as suggested by Phillips -0 et al. (1981). The Small White Bean (7813) was more thoroughly investigated by fractionation as outlined in Fig. 2. Fig. 2. Preparation of Small White bean (78131 fractions. 282 When the various fractions of &all White bean were fed to quail, all the birds died on fractions B,C,E and F (Fig. 3) in the first one week. The rest of the data are presented in Table 9. The growth of birds on autoclaved fractions A and D was about the same, but better than of birds fed isolated soybean protein diets. These data bring out the importance of varietal differences, and of the difficulty of designing diets for evaluation of an ingredient. source of tryptophan and can be used in supplementing a cereal such as corn when used up to 39% of the diet (Pea et al. 1983). Studies at Davis also suggested thatautoclaved beans are a good Table 6. Average larval weights fed 4 different bean flour preparations, arranged according to bean seed color, type and origin. 283 The data suggest that tribolium larvae can be used for screening nutritive value of beans. However, the information developed on tribolium cannot be strictly extrapolated to poultry or rats; and the use of data from these animals to predict the effect on humans is equally The beans do possess antinutrients and toxins which can be overcome with proper heating. The heated beans still need supplementation with methionine. The importance of methionine supplementation of beans is well documented (Infante et al. 1979; Tobin and Carpenter, 1979). However, varietal differezare evident even after methionine supplementation. EVALUATION WITH JAPANESE QUAIL The results of feeding these beans to quail are given in Table 7. Table 7. The body weights, pancreas and liver weights of Japanese quail fed bean diets unsupplemented with methionine, or a commercial poult starter. The results of feeding experiment (Table 7) indicated that without methionine supplementation, the growth of quail was significantly less on diets containing heated soybean meal than on diets containing autoclaved beans. The colored varieties were inferior to the white variety in absence of supplementary methionine. No significant differences were observed in pancreas and liver weights. diets lower other color These varietal differences disappeared after supplementation of the with 0.4% methionine (Table 8). Liver weights were significantly on diets containing soybean meal and Sutter Pink beans than on treatments. If methionine was not deficient in the diet, bean had no influence on their nutritive value. 284 Table 8. The effect of methionine supplementation of beans on the gain in body weight, pancreas and liver weights of Japanese quail. Table 9. The effect of Small White bean fractions on weight gains, pancreas and liver weights of Japanese quail. REFERENCES AOAC. (1970). Official Methods of Analysis, 11th ed. Association of Official Agricultural Chemists, Washington, `DC.. ALLI, I., and BAKER, B.E. (1981). J, Sci. Food Agric. 32: 588. =Jf=, K-8 and BENDER, A.E. (1980). J. Sci. Food Agric?31: 448. ANTUNES, P-L-t and SGARBIERI, V.C. (1980). J. Agric. FoodChem. g: 935. BENDER, A.EIl and REAIDI, G-B. (1982). J. Plant Foods, & 15. BRESSANI, R. (1972). In 'Nutritional Improvement of Food Legumes by Breeding', p.15,'editor M. Milner. (John Wiley: New York.) DeVARIES, J.W., KOSKI, C-M., EGBERG, D.C., and LARSON, P.A. (1980). J. Agric. Food Chem. 28: 896. 285 ELIAS, L.Gt FERNANDEZ, D.G.D., and BRESSANI, R. (1979). J. Food Sci. 44: 524. EvANSTR.J., and BAUER, D.H. (1978). J. Agric. Food Chem. 26: 779. KVNJS, A.M. (1979). In 'Evolution of Crop Plants', editor, 7-W. Simmond. (Cmqmsn: New York.) GATEHOUSE, M.R.# GATEHOUSE, J.A., DOBIE, P., KILMINISTER, A.M., and BOULTER, E. (1979). 3. Sci. Food Agric. 30: 948. INFANTE, M-H., PENA, G.H. I and LOPEZ, A.S. (19%). J. Agric. Food Chem. 27: 965. JAFFE7W.G. (1973). In ' Nutritional Aspects of Common Beans and Other Legume Seeds as Animal and Human Foods', p-199, editor W.G. JAFFE. (Archives Latinoamericanos de Nutrition: Caracas.) JAFFE, W.G. (1980). In 'Toxic Constituents of Plant Foodstuffs', p-73. editor I.E. Liener 8 (Academic Press: New York.) JAFFE, W.G.# and 'UTTE, C.L.V. (1973). J. Nutr. 94: 94. JAYNE-WILLIAMS, D.JIl and BURGESS, C.D. (1974). r appl. Bact. 37: 149. KAKADE, M-L:, HOFFA, D-E., and LIENER, I.E. (1973). J. Nutr. 1Or- 1772. KAKADE, M. L- I RACKIS, J.J., McGHEE, J-E., and PUSKI, G. (1974). Cereal Chem. 51: 376. KHAN, M.A. ,%d GHAFOOR, A. (1978). J. Sci. Food Agric. 29: 461. LIENER, I. E. (1962). Am. 3. Clin. Nutr. 11: 281. LIENER, I. E .I and KAKADE, M.L. (19801. In ?i?oxic Consti .tuents of Plant Foodstuffs', editor I.E. Liener. (Academic Press: New York.) NOAH, J., BENDER, A.E. H REAIDI, G.B.8 and GILBERT, R.J. (1980). Br. Med. J. 180: 236. PENZ,Jr?%.M., EARLE, L.fl KRATZER, F.H.v and TUCKER, C. (1983). Nutr. Reports International, 27: 161. PHILLIPS, D-E., EYRE, M.D., FOMPSON, A.l and BOULTER, D. (1981). J. Sci. Food Agric. 32: 423. PUSTZAI, A., CLARKE, E.M.W., GRANT, G., and KING, T.P. (1981). J. Sci. Food Agric. 3& 1037. REDDY, S.J.v MCGINNIS, J. 8 and BURKE, D. W. (1980). Poultry Sci. 1<3 572. ) ROY, D.N. (1981). Nutr. Absts. Revs., Series A.' 51: 691. SATHE, S.K.# and SALUNKHE, D-K. (1981). J. Food Sz. 4&: 626. SHARIFF, G.,.PENZ, Jr., A.M., and VOHRA, P. (1981). Nutr. Reports International, 24: 1087. TOBIN, G., and CARPEGER, K.J. (1978). Nutr. Abst. Rev.,.Series A, . 48: 919. UNTAWZ, G.GI8 and MCGINNIS, J. (1979). Poultry Sci. 58: 928. WHITAKER, J.RIt and FEENEY, R.E. (1973). In 'Tooxicants%xrring Naturally in Food& p.276. (National Academy of Sciences: Washington, D.C.) WYCKOFF, S., VOHRA, P., KRATZER, F.H., and CALVERT, C.C. (1983a). Poultry Sci. (in Press). WYCKOFF, S.; VOHRA, P.# and KRATZER, F.H. (1983b). J. Sci. Food Agric. (in Press).