Effects of storage conditions on the trypsin inhibitor content in flour and whole seeds of cowpea (Vigna unguiculata).

Cowpeas stored for 100 d under different conditions were evaluated for changes in trypsin inhibitor activity. Storage at 4 or 40°C produced reductions of antitryptic activity ranging from 20 to 30%. A high temperature (40°C) coupled to high relative humidity (95%) gave the maximum rate of trypsin inhibitor activity disappearance. The initial level of inhibitors remained unchanged for up to 130 d when the samples were stored at -20°C. The milling of cowpea seeds before storage neither prevented nor improved the loss of antitryptic activity. Reductions of trypsin inhibitor activity during storage may be relevant to the mechanism of cowpea resistance to storage pest attack