Effects of ultrasound-assisted extraction and transglutaminase treatment on the physicochemical properties of protein from Stropharia rugosoannulata

Protein from edible mushrooms can serve as a new alternative protein to replace meat in various food formulations. However, the processing characteristics of mushroom protein were poor. In this study, ultrasound-assisted extraction (UAE) and transglutaminase (TGase) were used for the modification of protein from Stropharia rugosoannulata (SRP) to improve its utilization. The optimal parameters of UAE were 480 W for 20 min. The process of TGase modification was optimized by a single-factor experiment and response surface test to obtain the TGase dosage of 0.36 % (w/w), cross-linking at 40℃ for 1.5 h, and reaction pH of 5.4. The effects of UAE and TGase treatment on the structure and functional properties of SRP were further investigated. UAE could improve the protein yield, the water and oil-holding capacity of SRP. The SRP was cleaved into small molecular fragments, and the protein particle size was decreased. The levels of β-sheet decreased, and the random coil increased by the UAE treatment. The water-holding capacity, oil-holding capacity, and emulsifying properties of SRP increased after the modification of TGase due to the cross-linking action. The results indicated that UAE and TGase treatment could alter the structure of SRP and improve its functional properties. Our results suggested that the UAE and TGase modification technology would be applied to the utilization of SRP as alternative protein for plant-based meat analogs in the future.