Extraction and Purification of Cowpea, Soybean, and Fishmeal Protein using Membrane Technology

Protein was extracted from cowpea, soybean, and fishmeal flours by ionic-strength and pH adjustment with different agitation speed at 250 and 900 rpm. After centrifugation, suspend solids in the extracts were removed by microfiltration, and the filtered extracts were purified by ultrafiltration. The protein extraction from cowpeas (51%) resembled that from soybeans (250 rpm) (55%) and exceeded that from fishmeal (20%); in the samples, extraction rate increased greatly as the agitation speed increased to 900 rpm. Ultrafiltration substantially purified the protein with minor loss of protein yields, 95% and 90% for soybean and cowpea flours, respectively. Low fat content in cowpea require less additional step to remove fat and purify the protein extracts. Therefore, cowpea flour can be an alternative protein source to soybean flour, and membrane technology is a viable option for extracting and purifying proteins such as those from cowpeas, and agitation substantially increased extraction rate.