Regression relationships for the soaking and cooking properties of two cowpea varieties

Water absorption and penetration depth (a measure of texture) of two cowpea varieties as influenced by varying soaking time (0.15-6 h) and soaking temperature (28-75 degrees C) were determined. The effects of different soaking treatments prior to cooking and cooking time on percent split, drained weight and the penetration depth of the cooked cowpeas were also investigated. The aim of the study is to establish mathematical relations between the product characteristics by regression statistics. Water absorption correlated positively with soaking time but the goodness of fit was temperature and variety dependent. Poor correlation coefficients were obtained when the penetration depth of the seeds was expressed as a sole (linear) function of soaking time or amount of water absorbed. However, equations involving both variables described the penetration depth of soaked cowpeas better. Cooking time correlated very well with drained weight (0.883 less than or equal to r less than or equal to 0.979), percent split (0.797 less than or equal to r less than or equal to 0.962) and penetration depth of cooked seeds (0.895 less than or equal to r less than or equal to 0.982). Equations involving drained weight and cooking time as variables were developed to predict the penetration depth of cooked cowpeas. The degree of fit increased with the inclusion of the product or higher order terms (0.841 less than or equal to r less than or equal to 0.996). (C) 1998 Elsevier Science Limited. All right reserved.