Effect of de cortication and roasting on trypsin inhibitors and tannin contents of cowpea (Vigna unguiculata L. Walp) seeds.

Abstract

This study was carried out to evaluate the nutritive value of cowpea seeds. Also to minimize the presence of some anti nutritional factors such as tannin and trypsin inhibitors. It is aimed to determined the best method by which we can reduce the anti nutritional factors. Samples of raw, decorticated and decorticated roasted cowpea seeds were subjected to proximate analysis. The results show that for dry matter (93.63, 94.33 and 95.9), for crude protein (29.18, 31.80 and 29.73), for ash (4.60, 4.0 and 5.52) for fiber (6.22, 3.75 and 4.32) for ether extract (2.30, 2.50 and 1.60) for nitrogen free extract (51.33, 52.28 and 54.73), respectively for raw, decorticated and decorticated roasted seeds. Tannin content percentages were determined using method. The results were (0.76, 0.02 and 0.005), respectively. Trypsin inhibitors were determined using enzymatic method the results were (1.68, 0.74 and 1.36), respectively for raw, decorticated and decorticated roasted cowpea seeds. It is concluded that chemical composition was varied between the treatments. Decorticated seeds gives high level of protein followed by the others. De cortication significantly reduced tannin content by 85%. Roasting significantly decreased trypsin inhibitors by 65%. Processing of cowpea seeds either mechanically or by heat, significantly improve their nutritional value.