Characterization and utilization of protein isolates of adzuki bean Vigna angularis Willd Ohwi Ohashi for health foods

Abstract

newline The present study was conducted to determine the nutritional, physico-chemical, and functional properties of the flour and protein isolates prepared from selected genotypes of adzuki bean viz. EC-340264, HPU-51 and Local Totru. Protein isolates were prepared by isoelectric precipitation. SDS PAGE electrophoresis and amino acid profiling of the protein isolates was done to analyse the quality of the protein present in the isolates. Various value added products viz. nutribar, instant protein shakes and biscuits were prepared by supplementing adzuki bean flour and protein isolates in the varying proportions. Nutritional evaluation of adzuki bean revealed that HPU-51 genotype had maximum protein content in both flour as well as protein isolate i.e. 24.03 and 76.56 per cent followed by in Local Totru and EC-340264. The protein isolates prepared from HPU-51 had maximum recovery and yield i.e. 16.07 and 51.69 per cent respectively. The DPPH free radical scavenging activity was highest in EC-340264 with 52.00 per cent inhibition. Protein isolates extracted from the adzuki bean had lower values for functional properties viz. water absorption capacity, emulsifying capacity, foaming capacity and foam stability except for fat absorption capacity which was higher in comparison to the commercial soy protein isolate. The results of SDS PAGE electrophoresis revealed that the molecular weight of adzuki bean seed protein and protein isolates ranged between 17.0 kDa to 117.0 kDa and 17.0 kDa to 56.23 kDa respectively. The essential amino acids like tryptophan, isoleucine, methionine and lysine were highest in the Local Totru flour i.e. 1.73, 0.10, 1, 75 and 0.44 g/100g respectively. The sensory acceptability scores of supplemented value added products revealed that good quality protein enriched products can be prepared by incorporating adzuki bean flour and protein isolates up to 30 and 6 per cent respectively.