COMPARATIVE-STUDY OF THE CHEMICAL-COMPOSI TION AND NUTRITIVE-VALUE OFSCARLET BEANS (PHASEOLUS-COCCINEUS) AND COMMON BEANS (PHASEOLUS-VULGARIS)

Comparative study of the chemical composition and nutritive value of s carlet beans (Phaseolus coccineus) and common beans (Phaseolus vulgari s) Scarlet beans (Phaseolus coccineus) is an important food grain legu me in the diet of rural populations living in the highlands of Mexico, Guatemala and other' countries of Latin America. The present study wa s conducted to obtain more chemical and nutritive data on this grain l egume, because of its importance in agricultural production systems an d due to the role it plays in rural diets. Ten samples were puchased i n the highland markets of Guatemala, to compare their physical, chemic al and nutritive characteristics with three samples of common beans (P haseolus vulgaris). A sample of 10 kg was used for nutritional studies , fed alone and in mixtures with maize. The results indicated that P. coccineus has greater weight as compared to P. vulgaris (0.74 vs. 0.18 g) and are larger in size (0.60 vs. 0.14 cc/grain). Seed coat percent age was 10.2% for P. coccineus as compared to 9.0% for P. vulgaris. Th e cooking time was 231 minutes for P. coccineus and 180 minutes for co mmon beans. Seed coat thickness and permeability are different when co mparing P. coccineus with P. vulgaris, since at 24 hr soaking time, P. coccineus absorbed 80% of its water weight as compared to 100% for co mmon beans. In chemical composition) small differences were found betw een P. coccineus and P. vulgaris. The first had slightly more ether ex tract, crude fiber and ash content than the second. Amino acid content among the six samples of P. coccineus was quite variable, but its pat tern was rich in lysine and limiting in sulfur amino acids. Cooking ti me at 3 hr gave a higher NPR than when cooked at atmospheric pressure for 5 hr, with protein values relative to casein of 69.2 and 60.0%, re spectively. P. coccineus protein quality was improved by methionine su pplementation, and it appeared to be better digested than that of P. v ulgaris. Mixtures of high protein quality were obtained with 15% P. co ccineus and 85% maize while common beans and maize mixed in a 30 to 20 ratio showed maximum protein efficiency. The digestibility of the P. coccineus/maize mixtures was higher than that of common beans and maiz e.