Effect of soaking and microwave pre-treatment of cowpea seeds on proximate composition, cooking quality and anti-nutritional factors

Abstract

Lengthy cooking times and the presence of anti-nutrients are factors contributing to the poor exploitation of the high protein content in cowpea seeds. This study was carried out to determine the effect of soaking and microwave energy pre-treatments on the cooking time, anti-nutritional factors and proximate composition of cowpea seeds. Seeds were soaked (6 h) and exposed to microwaves for 2 and 5 min followed by oven-drying (48 ± 2 o C) to obtain a uniform moisture content in the seeds prior to cooking. Soaking followed by 5 min microwave application reduced cooking time by 32% and 45.5% respectively. Soaking alone and in combination with microwave application resulted in significant (p<0.05) decreases in trypsin inhibitor activity, phytic acid and tannins; trypsin inhibitors being most affected. Protein, crude fiber, fat and ash contents were not significantly (p>0.05) affected by the microwave treatments, but were affected significantly (p<0.05) by the presoaking procedure possibly because of nutrient diffusion. The results of this study seem to suggest that soaking and microwave application may be useful in reducing the cooking time as well as anti-nutrients present in cowpea seeds.

Keywords: Cowpea, soaking, microwave, cooking time, anti-nutrients

IJOTAFS Vol. 1 (1) 2007: pp. 8-12