Stduy On Relationship Between Post-Harvest Oxidative Damage And Octanol Compounds Metabolism Of Lentinus Edodes

Lentinus edodes is an important edible fungus resource in the world,with high edible and medicinal value.China is a big country in the production of L.edodes.The cultivation of L.edodes has a long history.After the L.edodes are harvested,the physiological metabolism will continue to occur,such as browning,dehydration,and shrinkage,which seriously affects the sensory quality and nutritional value of L.edodes.Therefore,the freshness of the L.edodes is very important.In addition,L.edodes has a unique aroma with a wide variety of flavor substances and complex ingredients.The octanol compounds in fresh L.edodes are the characteristic flavor substance with a strong mushroom flavor.However,the post-harvest metabolic changes of octanol compounds are unclear,and its biosynthetic pathways are inconclusive.Study on the post-harvest flavor substance metabolism of fresh L.edodes is the basis for the development and utilization of flavor substances.In this study,L.edodes was used as a raw material and stored at three different temperatures(4℃,10℃,25℃).The changes of browning index,weight loss,reactive oxygen species metabolism,antioxidant activity,the metabolism of octanol compounds in L.edodes at different temperatures was studied,the relationship between these various parts was analyzed.The main findings are as follows:(1)The relative conductivity,MDA content,reactive oxygen species content and carbonyl protein content at 4℃ were all lower than those of the other two groups.The content of total phenol and ascorbic acid in L.edodes was maintained at 4℃,and the cell structure of L.edodes was more complete compared with the other two groups,Therefore 4℃ is a suitable temperature for storing L.edodes.Analysis of the correlation shows that browning of L.edodes is related to ascorbic acid and weight loss rate.Lipid peroxidation and protein carbonylation are related to reactive oxygen species metabolism.(2)According to the correlation analysis between the metabolism of octanol compounds and the oxidation of L.edodes,it can be known that the octanol compounds are formed by unsaturated fatty acids which are oxidized by LOX and ADH.Lipid peroxidation is an important way for the synthesis of octanol compounds.Lipid peroxidation mediated by ROS leads to the decomposition of unsaturated fatty acids,which further promotes the oxidation of LOX to produce octanol compounds.(3)Temperature has a regulating effect on the synthesis and accumulation of octanol compounds.After harvest,the content of the octanol compounds first increased and then decreased.The synthesis rate in the early storage period was large,and the synthesis rate in the later period was less than the volatilization rate,therefore the content gradually decreased.The peak content of the octanol compound at 4℃ was significantly lower than the other two groups,indicating that the lower temperature inhibited the synthesis of the octanol compounds.The reason is that the lower temperature can inhibit the activity of LOX,HPL and ADH,the occurrence of lipid peroxidation was suppressed in the same time,and further delay the degradation of unsaturated fatty acids.However,the content of the octanol compounds is relatively stable under low temperature conditions,so the lower temperature can maintain the content well and inhibit volatilization,the content is higher than the other two groups at the end of storage.Therefore,storage of L.edodes at 4℃ is not conducive to the synthesis of octanol compounds,but it can effectively maintain its content and maintain flavor.