Evaluation of the chemical qualities and microstructural changes of Lentinula edodes caused by airborne ultrasonic treatment combined with microwave vacuum drying

This study analyzed a new drying method using airborne ultrasound combined with microwave vacuum to study its effect on the quality characteristics and microstructure of dehydrated L. edodes. Ultrasonic treatment resulted in many micropores in the product, forming the sponge effect caused by ultrasonic waves, which can promote the rapid evaporation of water in the product. Samples of Lentinula edodes individuals were dried using four methods: hot air drying (HAD), microwave vacuum drying (MVD), microwave vacuum drying after ultrasonic pretreatment (US+MVD) and airborne ultrasonic treatment combined with microwave vacuum drying (USMVD). The results showed that USMVD can reduced the loss of total sugar, total phenol, and total antioxidants in L. edodes, and increased the relative content of ergosterol, sulfur compounds, and free amino acids (p < 0.05). Scanning electron microscope observation revealed that USMVD resulted in a uniform reticular porous structure, which could better maintain desirable levels of nutrients. Therefore, USMVD can produce high quality products. Practical Application Airborne ultrasonic waves combined with MVD provides an innovative drying method for mushrooms, which has not been studied at present. The mixed drying method has great potential in maintaining product quality. It provides a theoretical basis for studying drying technology in the future.