The effect and mechanism of ultrasonic treatment on the postharvest texture of shiitake mushrooms (Lentinula edodes)

Fresh shiitake mushrooms (Lentinula edodes) are prone to texture softening and quality decline during storage. We investigated the effects of prestorage ultrasonic treatment on the textural changes of the mushrooms during storage. We monitored physiological parameters, such as respiration intensity, weight loss, cell wall composition and resistance-related enzymes activity. The hardness of the ultrasonic-treated (40kHz, 80WL(-1), 20min) mushrooms after 12days of storage (0.461N) was significantly higher than the untreated control group (0.286N). The weight loss and respiration intensity of the ultrasonic-treated group were significantly lower, whereas the cell wall contents, including glucan and chitin, were significantly higher. The ultrasonic-treated mushrooms also had higher phenylalanine ammonia lyase, superoxide dismutase and catalase activities. Thus, ultrasound preserves the texture of mushrooms by reducing metabolic rate, maintaining cell wall compositions, activating the activity of SOD and maintaining the activity of PAL and CAT.