Significance of various antiphysiological and nutritional factors on the biological evaluation of various cultures of the common bean (Phaseolus sp.)
Fukuda, G.; Elías, L.G.; Bressani, R.
Archivos Latinoamericanos de Nutricion 32(4): 945-960
1982
ISSN/ISBN: 0004-0622 PMID: 7186348 Document Number: 184910
Raw and cooked samples of beans supplemented with methionine were used to prepare 35 rat diets containing different amounts of methionine, tannins, and trypsin inhibitors. The effect of these diets on weight gain, mortality and protein utilization was measured. The weight gain/protein consumption ratio increased while mortality decreased as the proportion of raw beans decreased in the diet. The effects of diet, beans and their interaction were significant. Supplementation with methionine had no effect in diets with high proportions of raw beans, but it had a significant effect on the biological response to diets with high proportions of cooked beans. The high and early mortality that occurred with diets with a high content of raw beans did not permit the adequate determination of apparent digestibility. In diets with a high concentration of cooked beans, digestibility was higher for white than for black or red beans. Since methionine supplementation had no effect on digestibility, it is suggested that heat-induced changes in the protein could be of great importance in the improvement of bean protein. At the same time, heat destroys the antiphysiological factors, since no definite detrimental effect was observed in the cooked samples due to these factors. It is concluded that the low nutritive value of cooked beans is due to a deficiency of sulfur-containing amino acids, and that the structure of the protein is a factor of the utmost importance in determining its digestibility.