The Antibacterial Mechanism Of Parsley Phenol On Vibrio Parahaemolyticus The Application Of Nano Iotion In Salmon Preservation

Vibrio parahaemolyticus(VP)is a Gram negative bacterium that is an important cause of seafood pollution and poses a serious threat to consumer health.The abuse of antibiotics has led to the emergence of various drug-resistant strains,posing a serious challenge to the control of V.parahaemolyticus.Therefore,seeking safe and effective methods to control V.parahaemolyticus in seafood is of great significance.Plant essential oils have the advantage of broad-spectrum and efficient antibacterial properties without causing bacterial resistance,making them an effective substitute for traditional antibacterial agents.As the main component of oregano essential oil,carvacrol has good antibacterial activity against a variety of pathogenic bacteria.It has been confirmed that carvacrol has inhibitory effect on Escherichia coli,Staphylococcus aureus,Salmonella typhimurium,Salmonella enteritidis,Helicobacter pylori and other bacteria,but the research on the antibacterial effect of carvacrol on V.parahaemolyticus has not been reported yet.Due to its instability and limited partial dissolution in water,parsley phenol has limited its application in the food industry.In this paper,the germicidal effect of carvol on V.parahaemolyticus was investigated.Carvol was prepared into carvol nano lotion through nano lotion technology and applied to the storage of fresh salmon.The main experimental results are as follows:Ⅰ The bactericidal effect and mechanism of parsley phenol on V.parahaemolyticusCarvacrol has an inhibitory effect on the growth of V.parahaemolyticus in a dose-dependent manner.The minimum inhibitory concentration(MIC)of carvol is 64 μg/m L,minimum bactericidal concentration(MBC)is 128 μg/m L 。 Using propidium iodide(PI)to stain V.parahaemolyticus,flow cytometry and fluorescence microscopy were used to determine and observe the V.parahaemolyticus treated with carvacrol.The results showed that carvacrol could damage the cell membrane of V.parahaemolyticus and increase its permeability.The membrane potential of V.parahaemolyticus cells was measured by microplate reader.The results showed that the membrane potential of the cells changed and the cells appeared depolarization.Further measurement of reactive oxygen species(ROS)levels in V.parahaemolyticus cells treated with carvol showed that carvol can cause intracellular ROS accumulation in V.parahaemolyticus,leading to oxidative stress damage.Observing the cell morphology of V.parahaemolyticus through a scanning electron microscope,the cells of V.parahaemolyticus treated with carvacrol showed signs of rupture and shrinkage.Ⅱ Preparation of carvol nano lotion by high-pressure homogenizationIn this paper,carvol nano lotion was prepared by two-step preparation method.First,a stable initial lotion was prepared by screening the ratio of emulsifier and distilled water.Furthermore,the content of carvol was screened,and the formula for preparing carvol nano lotion was obtained.The ratio of emulsifier to distilled water is 1:9,and the content of carvol is 3%.The physicochemical properties of nano lotion,such as ionic stability,thermal stability,freeze-thaw stability,and storage stability,were characterized.The results showed that the carvol nano lotion had good thermal stability and ionic stability.At the same time,the stability of carvol nano lotion at different storage temperatures was investigated,and it was concluded that carvol nano lotion was more suitable for storage at 4 ℃ in a dark environment.Ⅲ Application of carvol nano lotion in fresh salmonTo explore the effect of carvol nano lotion on the inhibition of V.parahaemolyticus and salmon quality during the storage of salmon meat,and simulate the changes of physical and chemical indexes in salmon meat during the actual storage of 9 days.The experimental results showed that carvol nano lotion treatment significantly inhibited V.parahaemolyticus in salmon meat during storage.At the same time,carvol nano lotion treatment also significantly inhibited the water loss rate of salmon meat,the production of total volatile basic nitrogen(TVB-N),lipid oxidation(TBA)and the change of color difference(P<0.05).To sum up,this study has proved the inhibitory effect and mechanism of carvol nano lotion on V.parahaemolyticus,and prepared it into nano lotion for the preservation of salmon meat,laying a theoretical foundation for the application of carvol nano lotion in the food industry.