Optimization of Ultrasonic Combined Microwave-assisted Extraction of Ergothioneine in Pleurotus eryngii by Response Surface Methodology

In order to optimize the extraction process of ergothioneine in Pleurotus eryngii,the effects of drying method,liquid to material ratio,ethanol concentration,microwave conditions and ultrasonic conditions on the extraction of ergothioneine in Pleurotus eryngii were studied with the content of ergothioneine as indicator. And the response surface methodology which was based on the single factor experiment was conducted to obtain the optimum formulations of extraction of ergothioneine in Pleurotus eryngii. The results showed that the content of ergothioneine in Pleurotus eryngii was(0.20±0.02) mg/g wet weight after vacuum freeze-drying,which was significantly higher than that obtained by hot air drying(P<0.05),but it was not significant difference with fresh Pleurotus eryngii(P>0.05). This indicated that the vacuum freeze-drying treatment could well retain the ergothioneine in Pleurotus eryngii. The optimum conditions for the extraction of ergothioneine in Pleurotus eryngii by ultrasound combined microwave were as follows:Liquid to material ratio 48:1 (mL/g),53% ethanol,microwave conditions(500 W,65℃,5 min),ultrasonic conditions(450 W,5 min). Under this optimized condition,the extraction of ergothioneine was(3.79±0.02) mg/g DW,and the error with the predicted value was within 1%. The optimized process conditions obtained in this study had certain feasibility,which could provide reference for the extraction of ergothioneine in edible fungi,and had broad application prospects.