Protein Insolubilization and Thermal Destabilization during storage as related to hard-to-cook defect in cowpeas

As storage duration at 30 o C/64% RH increased from 0 to 18 months, hard-to-cook (HTC) state of cowpeas (Vigna unguiculata) increased from 15.8 to 91.2 N/g, protein water extractability decreased from 76.5 to 11.2%, protein thermal transition temperature (T m ) decreased from above 100 to 56 o C, and starch gelatinization temperature remained constant at 64-73 o C. A decrease in tissue pH from 6,64 to 5.57 was also found with storage duration and correlated well with HTC state