Physicochemical and functional characterization of yellow-field pea vicilin and legumin fractions

In this study, legumin-enriched and vicilin-enriched fractions were isolated from raw pea flour using the pH-shift method. Following isolation, the fractions were investigated and compared with the pea protein concentrate (PPC) for their chemical and nutritional contents, as well as physicochemical and functional properties. The protein content was highest in vicilin (69.67%), followed by PPC (67.65%) and legumin (60.91%). Vicilin also exhibited the highest surface hydrophobicity (13.89), while PPC had the lowest (1.92). Moreover, vicilin demonstrated superior water-holding capacity (1.72 at 40 mg/mL) compared to legumin (0.38 at 40 mg/mL) and PPC (0.31 at 40 mg/mL). In contrast, PPC exhibited better oil holding capacity (0.58 at 40 mg/mL) than legumin (0.23 at 40 mg/mL) and vicilin (0.21 at 40 mg/mL). Legumin showed the highest protein digestibility (89.73%) while PPC had the lowest least gelation concentration (8%) among the three samples. Protein solubility was lowest in vicilin at pH 3 (0%), and lowest in legumin and PPC at pH 5 (0% and 0.56%, respectively). Notably, protein solubility was highest in vicilin and legumin at pH 8 (99.96% and 92.97%, respectively), and highest in PPC at pH 9 (45.66%). With respect to foam capacity, legumin showed the lowest at pH 5 and the highest at pH 3, whereas vicilin had the highest at pH 9 and the lowest at pH 5. Overall, the results suggest that the vicilin and legumin fractions may serve as better ingredients for food formulation when compared to the PPC.