Nutrients responses of Pleurotus ostreatus to slow frozen storage in the short term

Abstract

To improve the understanding of changes happening with nutrients in Pleurotus ostreatus during slow frozen storage in the short term, the metabolite contents of the fruiting body were evaluated. The effects of slow freezing and short-term storage on the variations of nutrients were studied at two temperatures, −20 and −30 °C, at various time points during storage. The contents of reducing sugars and vitamin C at all the treatments showed sustained downward trends. In the pileus, the contents of polysaccharide, proteins, and amino acids increased at first, and then decreased. In the stipe, the contents of all the measured substances maintained a slow decline. The variations of α-amylase showed a general downward trend with the freezing time. The fluctuation of the activity of POD implied reactive oxygen species production. Significant differences between the freezing/storage at −20 °C and −30 °C were observed in the contents of polysaccharides, reducing sugars, proteins, amino acids and vitamin C. In brief, when 30 min slow freezing was applied, the contents of most of the compounds showed a downward tendency or “up-down” trend because of ice damage.