Effect of soybean substitution for cowpea on physical, compositional, sensory and sorption properties of akara Ogbomoso

Akara Ogbomoso was prepared from cowpea:soybean flour mixture ratios of 100:0, 80:20, 60:40 and 40:60. Physical, compositional, sensory and sorption characteristics of the akara were evaluated. Protein and fat content increased, while carbohydrate content decreased as the soy content of the flour mixture of akara Ogbomoso increased. There were no significant differences (P<0.01) in the colour, taste, aroma and overall acceptability for either the freshly prepared akara Ogbomoso or the akara Ogbomoso stored for 10 weeks. There were significant differences (P<0.01) in crunchiness, increasing as the soy substitution increased both in the freshly prepared and stored akara Ogbomoso. The adsorption isotherms of akara Ogbomoso varied with varying levels of soy substitution and at 20, 30 and 40°C, had sigmoid shaped, type II isotherms according to Brunauer-Emmet-Teller (BET) classification, and were affected by temperature and composition. Increased levels of soy substitution and temperature depressed the isotherms. Calculated monolayer moisture contents using BET and Guggenhein Anderson deBoer models decreased with increasing soy substitution and temperature.