Effects Of Cinnamaldehyde On Quality And Membrane Lipids Metabolism Of Postharvest Lentinus Edodes

Shiitake mushrooms are edible fungi with great nutritional value.However,the epidermis of Shiitake mushrooms is soft,which is easily damaged by external forces after harvesting.It will cause microbial infection and reduce the commercial value of Shiitake mushrooms.The cell membrane plays an important role in maintaining the normal physiological metabolism and cells’function.With the external stress,the cell membrane injury instantly.In particular,external stress causes disturbance of the cell membrane leading to a loss of membrane integrity.Phenol is catalyzed by phenolase,which contributing to browning of shiitake mushroom.Currently,Low temperature,modified atmosphere and chemical preservation are commonly preservation methods of shiitake mushrooms,but they have some limitations.Therefore,it is significant to find a safe,green and efficient preservative for shiitake mushroom industry.In this study,serial concentrations of cinnamaldehyde were used to treat Lentinus edodes,aming to study the effect of cinnamaldehyde on membrane lipid metabolism and quality of Lentinus edodes.Furthermore,sodium alginate was used as the wall material to embed cinnamaldehyde to explore the best preparation process of cinnamaldehyde/sodium alginate microcapsules.Consequently,the prepared microcapsules are applied to keep shiitake mushrooms fresh.Main results are stated as follows:1.Serial concentrations of cinnamaldehyde were used to treat Lentinus edodes.The results showed that cinnamaldehyde can maintain the integrity of cell membranes,restricted the contact of phenolase and phenol,and delayed the browning of shiitake mushrooms.During storage,the total phenol content and ascorbic acid content of Lentinus edodes in the three treatment groups maintained a high level,and the browning index and PPO activity were kept at a low level.In addition,cinnamaldehyde can also inhibit the activity of PPO in mushrooms,delay the browning of mushrooms.Among them,the treatment effect of 0.15m L/kg was better among the three treatment groups.2.To study the effect of cinnamaldehyde on the membrane lipid metabolism of Lentinus edodes,the results showed that cinnamaldehyde can inhibit the increase of PLD activity,LOX activity and delay membrane lipid metabolism of Lentinus edodes.The membrane lipids of CK group and 0.15 m L/kg treatment group of Lentinus edodes were tested for 12days of storage.The results showed that there were 18 types of phospholipids in Lentinus edodes.Among them,phosphatidylcholine（PC）subtype had the greatest variety of class.When shiitake mushroom stored for 12 days,the PC content of the 0.15 m L/kg treatment group was significantly higher（P<0.05）than CK,and the PA content was significantly（P>0.05）lower than CK.Cinnamaldehyde effectively maintained the content of PC,PE and so on.Which Produced and maintained the integrity of shiitake mushroom membrane structure.The GC-MS results showed that palmitic acid,linoleic acid,and stearic acid were detected in the mushrooms.The cinnamaldehyde treatment of 0.15 m L/kg can maintain the content of unsaturated fatty acids.In addition,cinnamaldehyde can also decrease the damage of reactive oxygen species to cell membranes and maintain the integrity of cell membranes by inhibiting the generation rate of superoxide anions and the ability to generate hydroxyl free radicals in mushrooms.Moreover,it can reduce MDA content and increase relative conductivity.Among them,the treatment effect of 0.15 m L/kg was better than the other two treatment groups.3.To study the optimal preparation process of cinnamaldehyde/sodium alginate microcapsules,firstly,single-factor experiments are used to determine the optimal ranges of sodium alginate concentration,Ca Cl₂ concentration,and core-wall ratio to be 2.00～3.00%,2.00～3.00%,3:5～1:1.Through the response surface optimization experiment,the quadratic multiple regression equation is:embedding rate=-192.06+92.96A+78.11B-156.64C-0.42AB+14.17AC-16.13BC-21.17A²-12.34B²-90.47C²,each factor is paired The effect of embedding rate from large to small is core-wall ratio>sodium alginate concentration>Ca Cl₂concentration.It is determined that the optimized preparation process of cinnamaldehyde/sodium alginate microcapsules is as follows:sodium alginate concentration2.45%,Ca Cl₂ concentration 2.55%,core-wall ratio 4:5,under these conditions,the embedding rate reached 86.36%.The effect of cinnamaldehyde/sodium alginate microcapsules on postharvest fresh-keeping of mushrooms was studied.The results showed that the direct treatment of cinnamaldehyde was better than cinnamaldehyde embedding when stored for 0～6d.Buried is better than cinnamaldehyde treatment.