Effect of electron-beam generated X-ray irradiation on water status and microstructure of fresh Hericium erinaceus by LF NMR, MRI, SEM and TEM

Water loss poses a threat to the life of postharvest mushrooms. Clarifying the variation of water status in mushrooms and seeking an effective approach to postpone the water loss is of utmost urgency. This study assessed the application of electron-beam generated X-ray (EBGX) irradiation as a novel physical technology to maintain the postharvest storage quality of fresh Hericium erinaceus. Furthermore, the monitoring of changes in water distribution and migration as well as the tissue structure were conducted on irradiated (1.0, 1.5, and 2.0 kGy) samples using low-field nuclear magnetic resonance, magnetic resonance imaging, scanning electron microscopy, and transmission electron microscopy, respectively. Results indicated that the cell compartments of cytoplasm and vacuole constituted the predominant parts among the three water components in H. erinaceus matrix, whereas the water in the vacuole migrated to the cytoplasm after storage. Thereinto, the mushrooms irradiated with 1.0 kGy retarded water migration and contained more water components than those irradiated with 0, 1.5, and 2.0 kGy. Importantly, the dose of 1.0 kGy irradiation had a minimum weight loss of 2.19% and the best retention of color and texture after 9 d of storage. Additionally, low-dose irradiation with 1.0 kGy and 1.5 kGy remarkably improved the physical microstructure of H. erinaceus, while 2.0 kGy irradiation was prejudicial to the tissue structure. Taken together, the dose of 1.0 kGy was the most beneficial in maintaining postharvest quality of H. erinaceus. These findings provide insights into the changes in water status of H. erinaceus and the effects of EBGX irradiation on postharvest quality and deepen our understanding of the underlying mechanism whereby EBGX improves the freshness of H. erinaceus.