Compositional and protein digestibility changes in maize ( Z. mays) and cowpea ( V. unguiculata) after storage at ambient conditions

Abstract

Grains of maize and cowpea were stored in cloth bags for 7 months under ambient conditions of temperature (18–35·6°C) and relative humidity (30–97%). There were no significant changes in the total soluble sugars, free amino nitrogen, titratable acidity or pH of the grains ( P > 0·05). There was a decrease in the in-vitro protein digestibility of corn grains and an increase in the protein digestibility of cowpea grains ( P < 0·05). Cooking of stored corn grains resulted in an increase in the true digestibility above the level for the fresh sample ( P < 0·05). Depreciation in the protein digestibility of grains during storage may be relevant to only the raw samples.