Targeted Screening Of Anti-bacterial Substance Against The Spoilage Bacterial In Surimi Product And The Evaluation Of Application

Surimi products become more and more popular for its nutrient-rich, affordable, convenient to eat, etc, and have become one of the fastest growing, and the most exporting aquatic products in recent years. But surimi products can be easily spoilage and putrefaction by microorganisms because of their high water content and nutritious. Search safe and efficient natural food preservatives have become the important subject in food science and bio-pharmaceutical field.This thesis aims to the important subject that now surimi products can be easily spoilage and putrefaction for lack of high efficinency safe prescrvative, which influence the processing production of surimi products. By establishing targeted screening antibacterial model, a series of plants extract were evaluated for finding a good resource as antibacterium materials. In this research, we found the Bayberry residue extracts had good antimicrobial effect. Further, we evaluated the effects of Bayberry residue extracts to surimi products from physicochemical and microbial quota and surimi sense properties. At the same time, the mechanism of antimicrobial activities of Bayberry residue extracts were inversigated using TEM.The main results are as follows:1. Use Serratia marcescens, Pseudomonas aeruginosa, Escherichia coli, Micrococcus luteus and other spoilage-related strains of surimi seafood as a screening inhibition activity of Micrococcus model, and test with17kinds of common plants such as Mulberry leaf, Lotus leaf, Bayberry residue, and so on. We found that inhibition activity of Pseudomonas aeruginosa were higher for Bayberry residue, goldthread root, Mulberry leaf; inhibition activity of Serratia were higher for Bayberry slag, giant knotweed, Mulberry leaf. Taking all factors such as bacteriostasis effects and production costs into consideration, we found the Bayberry residue can be selected as the research object for antibacterial products against surimi products spoilage and pathogenic bacteria. And more, we found that crude extract from the ethanol extract of four extracts with different polars, on with the antibacterial activity of Serratia marcescens and Pseudomonas aeruginosa descending order of Ethyl acetate> N-butanol phase> Petroleum ether phase>Aqueous. Based on this we investigated the combined effect of its ethyl acetate extract phase and tea polyphenol (antimicrobial). The result revealed that in37℃for24h there were obvious synergy for abnormal han Hudson yeast, but tiny superimposition effect for Gambogic micro coccus, Staphylococcus aureus, Pseudomonas, Escherichia coli.2. Carry out surimi products preservation effects research using Bayberry residue ethyl acetate extract which had been selected as candidate bio-preservative. Add Ethyl acetate, Tea Polyphenols to surimi products. Under the conditions of20℃, surimi products extended shelf life to5days, and the control group the shelf life was only3days. Chromatism research showed that the surimi products which dealed with Bayberry residue ethyl acetate extract stored for six days, there e had no significant change in colour and lustre compared with control group. Ethyl acetate+Tea Polyphenols initial antibacterial activity was significantly higher than that of Tea Polyphenols solution, and its antibacterial activity is higher than the final Ethyl acetate. It showed Bayberry residue ethyl acetate+Tea Polyphenols combination had good potential application.3. Explore the inhibitory mechanism of speculation from bacterial sub-cellular microstructure by biochemical analysis combined with electron microscopy, showed that Bayberry extract of ethyl acetate and n-butanol could increase Serratia marcescens and Gambogic micro coccus to release intracellular alkaline phosphatase and increase the electrical conductivity of bacteria broth. Further evidence of bacterial antimicrobial agent microstructure of the damaging effects of bacteria, transmission electron microscopy clearly reflected the contents of the treated cells appeared deficit. By biochemical analysis combined with electron microscopy, there were damage effects of varying degrees on cell wall and cell membrane. By inhibiting bacterial protein synthesis, bacteria to grow is restrained, meantime break bacterial cell wall and cell membrane, increase with the cell membrane permeability, resulting in a large number of mycelium intracellular inclusions release, causing the death of bacteria.To sum up, this thesis research results will provide a new idea and method to develop natural source antibacterial agents, to solve surimi products biological preservation and to prolong surimi products shelves period, and also offer certain basis for Bayberry residue comprehensive utilization and promotion of Bayberry residue processing industry technology.