• Alcalase most effectively hydrolyzes Auricularia delicata protein. • Enzymatic hydrolysis reduced the foaming and emulsifying characteristics of ADP. • Alcalase ADPEH had superior antioxidant activity than the other ADPEH and ADP. This study investigated the physicochemical properties, structural characteristics, and functional activities of Auricularia delicata protein (ADP) hydrolyzed by five proteases (alkaline, neutral, papain, protamex, and flavourzyme). The results showed that alkaline protease exhibited the strongest hydrolytic capacity, with the corresponding degree of hydrolysis reaching 23.4%. Structural analysis indicated that the enzymatic hydrolysis promoted the unfolding of the tertiary structure of ADP, which was specifically reflected by a red shift in the fluorescence spectrum. Meanwhile, FTIR measurements revealed a conformational transition of the protein secondary structure from ordered conformations (α-helix/β-sheet) to disordered conformations (β-turn/random coil). These structural changes significantly improved the physicochemical properties of the Auricularia delicata protein enzymatic hydrolysis (ADPEHs). The ADPEH produced by alkaline protease had the smallest particle size (192.1 nm), the lowest polydispersity index (0.27), and the highest absolute zeta potential value (-33.9 mV). In addition, enzymatic modification altered the amino acid composition of ADP, reduced its emulsifying and foaming properties, but significantly enhanced its antioxidant activity. The alkaline ADPEH showed the optimal antioxidant capacity: the scavenging rate of ABTS radicals reached 92.42% (IC₅₀: 0.043 ± 0.001mg/mL), the ferrous ion chelating rate was 80.41% (IC₅₀: 0.284 ± 0.001mg/mL), and the hydroxyl radical scavenging capacity reached 92.37% (IC₅₀: 3.213 ± 0.011mg/mL). In conclusion, this study confirmed that ADP hydrolyzed by alkaline protease possessed enhanced structural, functional, and physicochemical properties. The alkaline ADPEH has the potential to be used as a functional ingredient in the development of high-value health-oriented foods.
Shen et al. (Sun,) studied this question.