Effect of bean broth on the nutritive value and digestibility of beans

Abstract

Black, red and white beans were cooked (1 : 3, water: beans) at 120°C and 16 Ib in-2 for 20 min. Chemical analysis of the broth showed that it contained low levels of protein, ether extract, and carbohydrates and high levels of ash and polyphenols. The effect of the addition of bean broth, on the PER and digestibility of beans was studied in rats. PER values and protein digestibility decreased as the amount of bean broth increased in the diet. White beans showed highest values of PER, weight gain and protein digestibility. The latter was lower in the groups supplemented with methionine than in those not supplemented; there was no interaction beween level of methionine and amount of bean broth in the diet on digestibility. The effect of methionine was not related to either metabolic nitrogen in faeces or amount of food consumed. A high proportion of the faeces nitrogen was soluble in NaOH. When rats from the different groups were fed diets containing 18% bean protein and killed at 6 weeks of age they showed no difference in pancreas weight that could be related to the amount of broth in the diet, nor were the levels of trypsin in the pancreas or the amount of PABA excreted upon ingestion of BT-PABA related to the amount of broth in the diet.