EFFECT OF STORAGE TIME AND CONDITIONS ON THE HARD‐TO‐COOK DEFECT IN COWPEAS (Vigna unguiculata)

Storage under unfavorable conditions is known to adversely affect the cooking quality of legumes by leading to the “hard‐to‐cook” defect. This phenomenon was studied by examining the texture and microstructure of Ghanainan cowpeas, variet “Adua ayera,” following storage at 0°C 80% RH; 21°C 35% RH and 29°C, 85% RH for up to 12 months. Scanning electron microscopy revealed no changes in raw beans after 12 months storage but soaking in water produced a loss of some protein bodies in seeds stored at 29°C. Texture measurement indicated that the rate of cooking of the beans decreased with increasing storage temperature and that storage at 29°C introduced the formation of the “hard‐to‐cook” defect. The micro structure of the defective beans showed an incomplete break down of the middle lamella which may partially explain this defect.