Effect of Combined Physical Pretreatments and Enzymatic Hydrolysis on Straw Mushroom Hydrolysates and Their Application in Vegan Protein Bars

• Green pretreatments significantly influenced straw mushroom hydrolysates. • Subcritical water pretreatment and enzymatic hydrolysis enhanced protein and phenolic release. • Flavourzyme yielded higher TCA-soluble peptide yield, BCAA content, and FRAP activity. • Straw mushroom hydrolysates improved antioxidant activity in vegan protein bars. This study evaluated the impact of hydrolysate production using green technologies, including high pressure processing (HPP), gamma irradiation (GI), and subcritical water (SW) treatment, followed by enzymatic hydrolysis with Alcalase and Flavourzyme, on the compositional characteristics and antioxidant activities of Volvariella volvacea hydrolysates. Among the green technologies investigated, HPP yielded the highest TCA-soluble peptide yield (49.93 ± 0.83%), while GI achieved the highest extract yield (57.81 ± 0.50%) and protein recovery (58.21 ± 0.85%). SW pretreatment was most effective in enhancing phenolic release (13.89 ± 0.16 mg/mL) and overall antioxidant activity, highlighting its efficacy in liberating bioactive compounds. Under SW pretreatment, Flavourzyme hydrolysis yielded higher phenolic concentrations and FRAP activity; however, no significant differences were observed in DPPH radical scavenging capacity compared to Alcalase. In contrast, Alcalase hydrolysates exhibited superior extraction yield and protein recovery, which are critical for industrial production efficiency, while maintaining comparable antioxidant performance. Considering overall performance, the hydrolysates produced via SW pretreatment followed by Alcalase hydrolysis were selected for vegan protein bar fortification. Incorporation of hydrolysates (0 - 12% w/w) into vegan protein bars enhanced protein content, total phenolic content, and antioxidant activity without adverse effects on texture, confirming their functional contribution. These findings support the potential utilization of V. volvacea hydrolysates, produced using integrated green technology pretreatments followed by enzymatic hydrolysis, as sustainable natural antioxidants for functional food and nutraceutical applications.