Effects of germination and cooking on polyphenols and in vitro protein digestibility of horse gram and moth bean

Abstract

Changes in polyphenols and in vitro protein digestibility due to germination and cooking were studied in horse gram and moth bean. Horse gram had higher amounts of polyphenols than moth bean. Polyphenol content in horse gram decreased from 1.6% to 1.1% at 48h germination, but in moth bean there was a reduction in polyphenol content from 1.3% to 1.0% at 24 h germination with a significant increase from 1.0% to 1.7% at 36 h germination. Seeds germinated for 48 h also exhibited higher amounts of polyphenols than in raw moth bean. The germination had no effect on total protein content, but a progressive increase in free amino acid content was observed in both legumes. In the ungerminated form, horse gram protein was more digestible than moth bean protein. The in vitro protein digestibility of both the legumes increased during germination. Cooking decreased the protein digestibility of horse gram either in ungerminated or germinated form, but such a decrease was noticed in moth bean at only 36 h germination. Moth bean either in raw form or germinated for 24 h did not exhibit a decrease in in vitro protein digestibility after cooking. Cooking decreased polyphenol content by 20%–50%. The apparent decrease in polyphenols in moth bean and horse gram due to cooking has been attributed to a decrease in assayable polyphenols.