Preparation Of Antibacterial Films Of Linalool/PCL And Its Application In Preservation Of Salmon

In this paper,the relationship between the bacteria of salmon in different storage time was analyzed by high throughput sequencing.A dominant spoilage bacteria,Pseudomonas fragi MS02,was isolated,purified and identified.Then,the antibacterial membrane of linalool/PCL was prepared by coaxial electrospinning and its physical and chemical properties was characterized.The antibacterial mechanism of linalool and antibacterial films were studied by using the isolated Pseudomonas fragi MS 02 as the target bacteria.Finally,the antibacterial film was prepared into active antibacterial gasket and applied to salmon preservation experiment.The main results are as following:1.The bacteria relationship of salmon stored at 4?showed a trend of dynamic change.During the whole storage period,the total bacterial class of salmon was 210,and the bacterial classes observed from 0 d to 12 d were 121,104,125,135 and 128,respectively.Photobacterium,Pseudomonas,Ralstonia and Acinetobacter were the dominant bacteria in salmon during storage.With the increase of storage time,the relative abundance of Pseudomonas gradually increases,while Pseudomonas fragi was the fastest growing strain in the storage period.Finally,a strain of Pseudomonas fragi MS 02 was successfully isolated and purified from the rotten salmon.2.LL/PCL nanofiber membranes were successfully prepared by coaxial electrospinning.The results show that the microstructure of LL/PCL nanofiber membranes were good,and the fiber surface was smooth and uniform.The fiber diameter of PCL membrane without core material is 113.92±23.74 nm.In contrast,the diameter of the coaxial nanofiber membrane with linalool was increased,and the diameter of the LL/PCL membrane with 20%and 40%linalool was 220.62±44.01 nm and 232.22±56.27 nm,respectively.The hydrophobicity and water vapor permeability are enhanced,but the tensile strength and elongation at break are slightly decreased,while the thermal stability has no significant difference.Sustained release experiments showed that linalool could be discharged to the reaction system for a long time.3.The antibacterial properties and antibacterial mechanism of linalool and LL/PCL coaxial fiber membrane were studied by using Pseudomonas fragi MS 02 which isolated and identified.The results showed that linalool had a good antibacterial effect.Linalool in LL/PCL coaxial fiber membrane could be discharged into the reaction system to exert its antibacterial effect.SEM results showed that linalool could make bacterial cell membrane produce concave folds,while conductivity,OD_{260 nm}value,FDA fluorescence intensity and AKP The ATPase activity showed that linalool could destroy the permeability and integrity of cell membrane and cell wall,affect the normal energy metabolism and lead to the death of the bacteria.4.Active antibacterial gasket was prepared by LL/PCL coaxial fiber membrane and applied to the fresh keeping experiment of salmon stored at 4?.The sensory evaluation,total bacterial count,p H,TBA,TVB-N,water distribution,texture characteristics and electronic nose of salmon slices were detected and analyzed.The results showed that the fresh degree of salmon was not affected by food tin paper and PCL gasket,the critical point of inedible was reached at the 8th day of storage,and it was completely corrupt at the 12th day of storage.The LL/PCL electrospinning antibacterial gasket containing linalool can slow down the corruption rate of salmon by releasing linalool.It was only at the 12th day of storage that it was near the inedible critical point,and the period of complete corruption was also delayed,which indicates that antibacterial gasket can effectively prolong the shelf life of salmon.