Effect And Prediction Of Exogenous NO Synergistic 1-MCP On The Shelf Life Of Postharvest Agaricus Bisporus

Object:To study the effects of nitric oxide（NO）or 1-methylcyclopropene（1-MCP）alone and combined treatment on the postharvest shelf-life quality of Agaricus bisporus,and to establish the corresponding shelf-life prediction model to provide theoretical basis and technical support for postharvest preservation and shelf-life prediction of Agaricus bisporus.Methods:The Agaricus bisporus（W192）was used as the test material.The effect of sodium nitroprusside（SNP）and 1-MCP alone or combined treatment on the quality of Agaricus bisporus during 14 days of storage at low temperature（0℃）was investigated.Agronomic traits such as hardness,color difference,respiration rate,weight loss rate,antioxidant enzyme activity,non-enzymatic antioxidant content and flavor were measured every 2 days.In addition,the Arrhenius model and chemical quality kinetic model were combined to establish the changes in hardness,L^*,weight loss,total phenol and flavonoid contents during storage at four temperatures 0℃,8℃,16℃and 25℃for the blank treatment（CK）and compound treatment（SNP+1-MCP）,and developed the model for predicting the shelf life of Agaricus bisporus.Results:（1）Under 0℃ storage conditions,compared to CK treatment,SNP,1-MCP and SNP+1-MCP treatments retarded browning of Agaricus bisporus,and SNP+1-MCP treatment has the best effect.The main manifestations were up-regulation of superoxide dismutase（SOD）,catalase（CAT）and peroxidase（POD）activities,activation of ascorbic acid and glutathione cycle（As A-GSH）,reduce the accumulation of reactive oxygen species（ROS）such as superoxide(O₂^·-),hydrogen peroxide（H₂O₂）and hydroxyl radicals（·OH）,reduction of malondialdehyde（MDA）content,maintenance of cell membrane integrity,thus preventing polyphenol oxidase（PPO）from binding to the substrate,inhibiting PPO activity,effectively reducing browning and maintaining the unique flavor of Agaricus bisporus（flavoring nucleotides and amino acids）.Meanwhile,all treatments（SNP,1-MCP and SNP+1-MCP treatments）effectively inhibited the decrease of As A,GSH,total phenol and flavonoids contents in Agaricus bisporus,and the treatment effects were SNP+1-MCP>SNP>1-MCP>CK.（2）The hardness,L^*,weight loss rate,total phenol and flavonoid content of Agaricus bisporus were significantly changed by temperature,and low temperature could effectively extend the shelf life of Agaricus bisporus.The coefficients of determination R² of the shelf-life prediction models based on hardness,L^*and weight loss indexes were all above 0.87,and the relative errors were within±10%using 4℃and 20℃to validate the models.For the CK treatment,the relative error value of the shelf-life prediction model built with brightness was the smallest,while the relative error value of the shelf-life prediction model built with weight loss rate was the smallest for the SNP+1-MCP treatment.Conclusions:（1）SNP+1-MCP treatment can effectively maintain the quality of Agaricus bisporus,delay the browning of Agaricus bisporus,and extend the shelf life of Agaricus bisporus at 0℃to 14 days.（2）The model based on hardness,weight loss and L^*indexes helped to accurately predict the quality deterioration of Agaricus bisporus in the postharvest temperature range of 0-25℃and the shelf life.