Abstract: In order to gain insight into the effect of positive modified atmosphere on the browning and polysaccharide bioavailability of Pleurotus nebrodensis, such physiological and biochemical indexes as oxygen and carbon dioxide concentrations, color difference, polyphenol oxidase (PPO) activity and polysaccharide bioavailability were measured on Pleurotus nebrodensis modified atmospheric packaged with PVC or PE films of different thickness (0.03 or 0.05 mm)or microporous film (0.015 mm) at regular time intervals during 28 days of storage at 4 ℃ and 95% relative humidity. A low-oxygen, high-carbon dioxide stable environment composed of 0.3%－2.1% O2 and 6%－10.3% CO2 was formed by 0.05 mm thick film on storage day 7 and could keep for 21 days. The environment could delay the occurrence of the PPO activity peak, inhibit the increase of PPO activity, and maintain polysaccharide bioavailability during the early part of the storage period. Different packages had no significant difference in their effect on the color of Pleurotus nebrodensis. Consequently, modified atmosphere packaging with 0.05 mm thick film could inhibit the browning of Pleurotus nebrodensis well, reduce the loss of nutrients and extend the storage life of Pleurotus nebrodensis.

Key words: Pleurotus nebrodensis, modified atmosphere package, browning, in vitro digests, bioavailability