Physicochemical and functional properties of Pleurotus eryngii proteins with different molecular weight

Pleurotus eryngii, rich in polysaccharides and proteins, is precious commercial edible fungus with favorable nutrition. In this study, four kinds of Pleurotus eryngii proteins (PEPs) with different molecular weight (PEP: control, PEP-I: >100 kDa, PEP-II: 50–100 kDa, PEP-III: 10–50 kDa) were prepared by alkaline-solution and ultrafiltration method. The results revealed that PEP-I (82.5 °C) and PEP-III (81.9 °C) with high denaturation temperature. Glu, Asp, Leu, and Lys were the most enriched amino acids in PEPs. The SDS-PAGE results revealed that a low molecular weight fraction of 17 kDa was clearly obtained in the PEP-III. The secondary structure of PEPs was mainly β-turn and β-sheet, and account for 79.8–90.3% of the total content. Moreover, PEP-II and PEP-III had better solubility and emulsification compared to PEP-I and PEP. Finally, the antioxidant capacity of PEPs, especially PEP-II and PEP-III, shown significantly ·OH scavenging capacity and Fe2+ chelating force. The key findings suggested in this paper refer to the exploration of functional properties and antioxidant activity of Pleurotus eryngii protein. The PEP-III with low molecular weight is potentially advantageous as a protein alternative resource application in the food industry.