| In this paper,methyl ferulate was used as the research object,and its antibacterial activity and basic physical and chemical properties were characterized in vitro.S.putrefaciens was used as the target bacteria to further explore the antibacterial mechanism of methyl ferulate.The coaxial methyl ferulate/zein fiber membrane was prepared by electrospinning technology.The properties of the fiber membrane were characterized,and the antibacterial and antioxidant effects of the fiber membrane were verified.Finally,the preservation effect of fiber film on sea bass was studied,and the following conclusions were drawn:1.In vitro antibacterial test showed that methyl ferulate had a good inhibitory effect on dominant spoilage bacteria,Gram-negative bacteria and Gram-positive bacteria in aquatic products.The best inhibitory effect on S.putrefaciens was 1.25 mg/m L,and the minimum bactericidal concentration was 5 mg/m L.The hemolysis test showed that methyl ferulate had no hemolysis effect on sheep red blood cells,and methyl ferulate could inhibit the hemolysis of sheep red blood cells at low concentration.In addition,high temperature and alkaline conditions will affect the antioxidant stability of methyl ferulate,which will greatly reduce the antioxidant activity of methyl ferulate.2.The antibacterial mechanism of methyl ferulate was studied with S.putrefaciens as the target bacteria.Scanning electron microscope(SEM)showed that methyl ferulate could destroy the integrity of cell membrane and make the cell contents leak out.The activity of alkaline protease showed that methyl ferulate could effectively destroy cell wall and expose cell membrane.The measurement of electrical conductivity showed that methyl ferulate could change the permeability of cell membrane and lead to the leakage of intracellular ions.The measurement of intracellular fluorescence intensity confirmed that methyl ferulate could enhance the permeability of cell membrane and make the contents of cells leak out.The Na~+K~+-ATPase experiment showed that methyl ferulate increased the ion permeability,inhibited the activity of Na~+K~+-ATPase,and inhibited the cell metabolism.The results of nucleic acid electrophoresis and total protein determination showed that the protein and DNA of macromolecule would leak out with the destruction of cell membrane by methyl ferulate.3.The coaxial methyl ferulate/zein fiber membrane was successfully prepared by electrospinning.The results of SEM showed that the fiber direction was random,network structure was formed,and the fiber diameter increased with the addition of methyl ferulate.Transmission electron microscopy showed that the core/shell structure of fiber membrane encapsulated methyl ferulate in zein.Mechanical properties test showed that the tensile strength of zein fiber membrane increased with the addition of methyl ferulate.X-ray diffraction showed that the crystallinity of methyl ferulate encapsulated by zein decreased and the crystallinity of the polymer weakened.Fourier transform infrared spectrometer analysis showed that the addition of methyl ferulate had no effect on the structure of zein,and the two proteins were mainly physical binding.The thermal performance analysis showed that the coaxial methyl ferulate/zein fiber membrane could improve the thermal stability of methyl ferulate.The water contact angle experiment showed that the addition of methyl ferulate changed the hydrophobicity of zein fiber membrane from hydrophobicity to hydrophilicity.The in vitro release of methyl ferulate/zein fiber membrane showed sustained release effect.4.The antibacterial activity and antioxidant activity of co axial methyl ferulate/zein fiber film were studied,and the preservation effect of fiber film on sea bass was studied.The results showed that the fiber membrane had sustained antibacterial effect on S.putrefaciens and good antioxidant activity.After the sea bass was coated with methyl ferulate/zein fiber membrane,the growth of microorganisms in the fish was inhibited by the fiber membrane,and then the increase of pH value and TVB-N content in the fish was effectively inhibited.At the same time,fiber membrane can improve the water holding capacity of sea bass and protect unsaturated fatty acids from oxidation.The results showed that methyl ferulate/zein fiber film could prolong the cold storage period of sea bass for more than 3 days,and had fresh-keeping effect on sea bass. |
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