Storage temperature effect on quality related with cell wall metabolism of shiitake mushrooms (Lentinula edodes) and its modeling

Fresh shiitake mushrooms (Lentinula edodes) are susceptible to temperature fluctuation, thus easy to soften. In this study, the effects of temperature during storage on the softening mechanism of postharvest shiitake mushrooms were studied. The firmness, cell wall polysaccharide contents, chitin and cellulose contents, cell wall degrading enzyme activities, and their gene expression levels were evaluated. The relationship between the indicators and the accumulated storage temperature was also analyzed. Results showed that decreasing firmness was concomitant with cell wall components reduction, the increase in enzymatic activities and gene expression levels. Increasing the storage temperature promoted these changes. Thus, cell wall polysaccharides modification induced by the cell wall degrading enzymes played a key role in the temperature-mediated softening mechanism of postharvest shiitake mushrooms. The firmness, 10 mol L-1 NaOH-soluble polysaccharide, total polysaccharide, chitin and cellulose contents, β-1,3-glucanase activity, expressions of Letlg1, Leglu1, Leexg1, Leexg2, Lepus30a and Lechi1 were fitted well with accumulated storage temperature, implying that they were related to the firmness loss and could describe the effects of storage temperature and time on softening process in shiitake mushrooms.