Physicochemical, Nutraceutical and Techno-Functional Properties of Germinated African Yam Bean Protein Concentrate

Germination is a widely recognized bioprocess that modifies the nutritional and functional properties of legumes. However, effects of germination on the properties of resulting protein concentrate from African yam bean (AYB) have not been adequately studied. This study investigated the effect of germination time (0, 24, 48 and 72 h) on the physicochemical, nutraceutical and techno-functional properties of AYB protein concentrate. Germination increased protein yield from 20.72% to 23.34% and protein content from 65.10 g/100 g to 67.88 g/100 g. Notably, the concentration of key amino acids increased, and significant improvement in vitro protein digestibility was observed ranging from 69.63% to 79.20%. Phytochemical and antioxidant activities representing nutraceutical potential were significantly (p ≤ 0.05) enhanced. Total phenolic content increased from 12.10% to 52.10% and total flavonoid content from 16.23% to 32.70%, while FRAP and ABTS increased from 93.21% to 172.20% and 73.56% to 180.66% respectively. Key functional properties relevant for food formulation were improved including protein solubility (63.29%-78.56%), emulsifying capacity (42.10%-56.23%), emulsifying stability (46.75%-70.65%), water absorption (2.51 g/g-3.12 g/g) and oil absorption capacities (1.22 g/g-1.83 g/g). The FTIR spectra exhibited consistent Amide I (1632 cm^-1) and Amide II (1543 cm^-1) bands across germination periods. Variations in amide band intensities, most pronounced at 24 h, indicated germination-induced changes in protein secondary structure conformation while preserving fundamental protein integrity. Correlation analysis showed that germination-mediated modulation of protein solubility, protein content, starch and fiber fractions, thermal transition parameters, and bioactive constituents critically underpins the techno-functional performance and antioxidant potential of the samples. These findings demonstrate that germination can be successfully used for improving the functionality of AYB protein concentrate as viable ingredient for the development of plant-based foods.