Effects Of O₂/CO₂ Active Modified Atmosphere Packaging On Storage Of Pleurotus Ostreatu

Mushroom is prone to dehydration,browning and microbial infestation after harvesting due to its strong respiratory metabolism,which results in short storage period of Pleurotus ostreatus.The modified atmosphere packaging?MAP?has achieved good results in the preservation of fruits and vegetables,and O₂/CO₂ active modified atmosphere packaging?Active MAP?has received more and more attention.This topic studies the effect of high O₂/CO₂ Active MAP on storage quality of Pleurotus ostreatus,which devotes to solving the preservation problem of Pleurotus ostreatus during storage and transportation.In this paper,the effects of different initial O₂/CO₂ proportion Active MAP on storage quality of Pleurotus ostreatus were studied.The suitable initial O₂/CO₂ proportion of Pleurotus ostreatus storage at different temperatures was investigated by determining respiratory metabolism,active oxygen regulation and browning control.The specific research results are as follows:1. For investigated the effect of O₂/CO₂ Active MAP on storage quality of Pleurotus ostreatus,initial proportions of 60%O₂+40%CO₂,70%O₂+30%CO₂,80%O₂+20%CO₂,90%O₂+10%CO₂ and natural air?CK?under 1?and 20?were designed,and initial proportions of 80%O₂+20%CO₂,90%O₂+10%CO₂,100%O₂ and CK under 10?were designed.Gas composition?CO₂,O₂?in each sealed box,prionus respiration rate,whiteness?L*?,polyphenol oxidase?PPO?activity,free amino acid and soluble protein?SP?and malondialdehyde?MDA?content,as well as ethanol and acetaldehyde content of Pleurotus ostreatus at different temperatures were periodically measured.The results showed that the respiration rate of Pleurotus ostreatus was significantly different under different temperatures and different O₂/CO₂ proportions.With the increase of temperature,the respiration rate of Pleurotus ostreatus increased in multiples,and the respiratory peak appeared earlier;the appropriate O₂/CO₂ treatment significantly delayed the respiratory peak and reduced the respiratory rate of Pleurotus ostreatus.Among them,70%O₂+30%CO₂at 1?,90%O₂+10%CO₂ at 10?,and 60%O₂+40%CO₂ at 20?all delayed the arrival of respiratory peaks,and significantly reduced the respiratory rate and weight loss rate.It decreased the accumulation of MDA,ethanol and acetaldehyde contents,and maintained the SP and free amino acid contents,which is conducive to the maintenance of the storage quality of Pleurotus ostreatus.2. For investigated the regulation of O₂/CO₂ Active MAP on the active oxygen metabolism of Pleurotus ostreatus,the active oxygen content,antioxidant enzyme activity and MDA content of Pleurotus ostreatus were measured periodically during storage.The results showed that 90%O₂+10%CO₂ treatment significantly increased superoxide dismutase?SOD?,catalase?CAT?activity and decreased superoxide anion?O₂·^-?hydrogen peroxide?H₂O₂?and MDA accumulation,reduced cell membrane lipid peroxidation,and ultimately delayed the aging of Pleurotus ostreatus at 10?.Similar results were also observed in the treatment of 70%O₂+30%CO₂ at 1?and60%O₂+40%CO₂ at 20?.It is indicated that Active MAP of the appropriate initial O₂/CO₂ proportion reduced the accumulation of active oxygen,increased the degree of cell membrane lipid peroxidation,inhibited the accumulation of MDA content,and finally delayed the senescence of Pleurotus ostreatus by enhancing the activity of SOD and CAT.3. For investigated the regulation of O₂/CO₂ Active MAP on the browning of Pleurotus ostreatus,the relative conductivity,polyphenol oxidase?PPO?,phenylalanine ammonia lyase?PAL?,whiteness?L*?and the total phenol content of Pleurotus ostreatus were periodically measured under different temperature and different initial O₂/CO₂ proportions.It was found that the suitable O₂/CO₂ Active MAP treatment inhibited the increase of relative conductivity and total phenolic content,decreased the PPO and PAL activity,and inhibited the L*decrease and finally controlled the browning.