Factors That Compromise the Nutritional Value of Cowpea Fluor and Its Protein Isolates

Abstract

Anti-nutritional studies on cowpea (Vigna ungiculata L.) seeds as whole cowpea flour (WCF), dehulled cowpea flour (DCF), dehulled defatted cowpea flour (DDCF) and protein isolates obtained from DDCF by isoelectric (CPIA) and micellization (CPIB) precipitation. The protein content of WCF and DDCF were 22.3% and 26.75% respectively, while CPIA and CPIB showed 75% and 76% respectively. The abundant minerals in WCF and DCF were calcium (32.38 - 33.61 mg/100 g); potassium (29.25 - 24.99 mg/100 g); and sodium (1.76 - 1.00 mg/100 g). The least abundant minerals were iron (0.004 - 0.013 mg/100 g); copper (0.04 - 0.25 mg/100 g); manganese (0.18 - 0.30 mg/100 g) and zinc (0.26 - 1.22 mg/100 g); respectively. Trypsin inhibitor activity for WCF, CPIA and CPIB was found 16,640 TIU/g, 4293 TIU/g and 4290 TIU/g respectively. Condensed tannins in RCF and DDCF were found 0.003% and 0.004% respectively while phytic acid content 0.8% and 1.17% respectively, no phytic acid and tannins were observed in protein isolates. Cowpea flour was also similar to other edible grain legumes in content of anti-nutritional factors; appropriate processing methods improved cowpea nutritive value and significantly reduced the levels of anti- nutritional factors.