The effect of heat treatment on the in-vitro multienzyme digestibility of protein of six varieties of African yam bean (Sphenostylis stenocarpa) flour

The in-vitro multienzyme protein digestibilities of the flours of six colour varieties of African yam bean (Sphenostylis stenocarpa), made from both hulled and dehulled seeds were investigated. The multienzyme system consisted of trypsin, chymotrypsin and peptidase. Digestibilities were determined for a 15 min digestion period. Both dehulling and heat treatment improved digestibility. Comparison of flours from raw hulled seeds with those from raw dehulled seeds showed that digestibility was 7% better in the latter. Heat-treated hulled-seed flours gave a digestibility increase of 6% compared with raw flours whereas in the dehulled samples the digestibility increase of heat-treated flours over raw was 5%. Heattreated dehulled seeds were better, with a digestibility increase of 6% over the heat-treated hulled seed flours. No significant differences (P < 0.05) were observed in the digestibilities among the whole-seed flours but significant differences were observed in the dehulled-seed flours.