Effects of alkaline extraction on the physicochemical and functional properties of protein concentrates obtained from Vigna mungo and Phaseolus vulgaris L. legumes

Legumes are well-known as sources of nutritionally desirable plant proteins. The objective of this research was to investigate the effects of alkaline extraction on the functional and antioxidant properties of protein concentrates obtained from Black gram (Vigna mungo) and red kidney bean (Phaseolus vulgaris L.) legumes. The alkaline extraction at pH 9.0 for soluble protein revealed significantly (p<0.05) the highest protein content (71-74%). The total essential and non-essential amino acids of Black gram and red kidney bean proteins increased approximately 3-fold when compared to the amino acid content of the flour. The molecular weight profile of the Black gram (BGP) and red kidney bean (RKBP) protein concentrates ranged from 12 to 100 kDa and 16 to 160 kDa, respectively. Results showed that the BGP and RKBP absorbed soybean oil in the range of 2.49 to 2.67 g of oil/ g protein. The protein concentrates had strong emulsion forming and stabilizing activity. In addition, the antioxidant activities of BGP presented significantly the highest capacity to scavenge ABTS•+ with a value of 421.80 mg TEAC/g sample. We conclude that these proteins have the potential to be used as ingredients to formulate functional foods against oxidative stress.