EFFECTS OF SOAKING TIME AND COOKING CONDITIONS ON TEXTURE AND MICROSTRUCTURE OF COWPEAS (Vigna unguiculata)

Abstract

ABSTRACT A method has been developed to measure the texture of raw and soaked cowpeas ( Vigna unguicuiata ) using a wedge‐type blade mounted in an Instron testing machine to cut across the cotyledons. It was found that soaking raw cowpeas in water prior to cooking produced a softer bean and the decrease in hardness was proportional to the soaking time. Texture of cooked beans could be predicted from the texture of the corresponding soaked bean. The influence of cooking temperature and time on bean texture was studied using the shear‐compression cell of ‐ the Texture Test System and the Ottawa Texture Measuring System cell with a wire extrusion grid. It was found that the rate of cooking relative to texture followed first order kinetics. Scanning electron microscopy was used to study changes in microstructure during the cooking process. The major effect observed was a breakdown of the middle lamella; cell walls remained intact.