Valorization of soybean residues (Okara): technofunctional properties of okara hydrolyzates using papain

Enzymatic hydrolysis of soybean by-products (okara) can influence the characteristics of okara hydrolyzates, such as enhancing their techno-functional properties, nutrition, and isoflavone content as a bioactive component. This study aimed to evaluate the impact of enzymatic hydrolysis using papain on the techno-functional properties of okara hydrolyzates, including their solubility, water-holding capacity (WHC), oil-holding capacity (OHC), emulsion activity index (EAI), emulsion stability index (ESI), turbidity, and viscosity. Gastric digestibility using pepsin, total amino acid content, and isoflavone content were also evaluated. The okara hydrolyzates exhibited better solubility and emulsion stability index than the control (p < .05), although their water- and oil-holding capacities were not significantly different from those of the control (p > .05). The okara hydrolyzates had lower turbidity, viscosity, and emulsion activity index than the control, which could influence its further application (p < .05). However, the total amino acid content was higher than that of the control group (p < .05). The gastric digestibility simulation results showed that okara hydrolyzates remained stable after 2 h of hydrolysis using pepsin compared to the control (p < .05). Enzymatic hydrolysis also enhanced genistein, a major isoflavone in okara, compared to that in the control (p < .05). Therefore, the present study revealed that enzymatic hydrolysis of okara using papain can enhance certain properties of the hydrolyzates, which can be beneficial for future applications in the food industry.