Study On Modified Atmosphere Preservation Technology And Odor Metabolism Of Fresh Cut Lentinula Edodes

Fresh-cut fruits and vegetables can meet people’s pursuit of natural,nutritional,fast-paced lifestyle needs.Lentinula edodes as fresh-cut material has the problems of strong respiration,high water content,perishable deterioration and so on.In this study,the variety selection and modified atmosphere preservation parameters were optimized.The changes of microorganism and odor substances during storage were analyzed to provide reference for alleviating the deterioration of fresh-cut mushroom,prolonging its storage period and increasing market share.（1）Screening of Lentinula edodes varieties suitable for fresh-cut processing:By analyzing the conventional nutrients,bioactive components,antioxidant activities and texture characteristics of different Lentinula edodes varieties,Lentinula edodes No.238collected from Beijing Tongzhou Sanbaoxiang Base was selected as the Lentinula edodes variety for fresh-cut processing.The polysaccharide content and flavonoid content of Lentinula edodes were 88.62 mg/g and 4.49 mg/g,respectively,and showed high antioxidant activity and texture characteristics,which could reduce the damage caused by mechanical cutting and was suitable for fresh-cut processing.（2）The determination of processing parameters of fresh-cut Lentinula edodes and the optimization of air conditioning preservation parameters:Firstly,the sensory evaluation of fresh-cut Lentinula edodes during storage was carried out.Then the processing parameters of fresh-cut Lentinula edodes were determined as strip speed 220cm/min and blade speed 440 r/min.The optimal thickness of Lentinula edodes slices was 5 mm.Finally,the single factor experiment was set up,fixed O₂concentration of5%,treatment group T1:15%CO₂,5%O₂,80%N₂;T2:20%CO₂,5%O₂,75%N₂;T3:25%CO₂,5%O₂,70%N₂.By observing the changes of nutrient composition,physical and chemical indexes and odor substances during storage,principal component analysis was carried out.The results showed that unwashed fresh-cut Lentinula edodes could preserve nutrients and quality to the maximum extent under the preservation conditions of T1 treatment group,and the shelf life of fresh-cut Lentinula edodes could be extended to 9 days.（3）Analysis of the odor change rule and quality change mechanism of fresh-cut Lentinula edodes:By analyzing the microbial flora on the surface of Lentinula edodes slices,combined with the results of transcriptome and metabolomics analysis of Lentinula edodes odor substances,the mechanism of odor and quality change of Lentinula edodes was analyzed.The results showed that with the extension of storage time,the microorganisms related to the change of mushroom odor components were Lactococcus and Pseudomonas,accounting for 47.10%and 10.33%of the total number of colonies,respectively.Among the odor components,17 substances mainly composed of 1-octene-3-ol showed an increasing trend with time,and 7 substances mainly composed of characteristic sulfide showed a decreasing trend.The carbohydrate metabolism and lipid metabolism of Lentinula edodes fruit body are closely related to the changes of Lentinula edodes odor.