Research On Improvement Of Antibacterial Stability Of Nisin And Its Application

Nisin is a natural antibacterial peptide used broadly as a food preservative in foodindustry. Nisin has narrow antimicrobial spectrum, short antibacterial aging and is subject tothe influence of temperature and pH value. In order to improve the antibacterial stability ofNisin and broaden its application in food, the effects of various factors such as temperature,pH, storage time, metal ion, various chelant and saccharides, milk on the antibacterial activityof Nisin against Micrococcus luteus were investigated by spectrophotometry in this paper.Furtherly, the stabilization mechanism of various additives on the activity of Nisin wasstudied by FTIR and DSC. RSM（Response surface method） was used to optimize theformula of four biopreservatives （isin, Tea Polyphenols （TP）, chitosan and EDTA） forimproving the characteristics and antimicrobial activity of Nisin. The changes in the indicesrelating to the shelf life and quality of cooked chicken wings coated with the compoundingpreservatives and sterilized thermally were determined during storage for searching acompounding method to prolong the shelf life of products storaged at room temperature. Theresults were showed as follows:1. Temperature, pH and storage time had significant effects on the activity of Nisin andthe activity of Nisin increased with temperature and pH increasing, storage prolonging.2. K+、Ca²⁺could protect the antibacterial stability of Nisin, and Fe²⁺、Ba²⁺showedstronger protection. While Na+、Mg²⁺enforced the damage of the antibacterial activity ofNisin.3. Phosphate salt、EDTA、sodium citrate could protect the antibacterial activity of Nisinpreferably. The protective effect lined from stronge to weak was as followed:SHMP>EDTA>STPP> Sodium Citrate>DSP>SDP. At pH6.8and121℃, the antibacterialactivity of Nisin was decreased by7.25%and10.2%with SHMP and EDTA adding,respectively.4. Sucrose、trehalose、chitosan and milk could protect the antibacterial stability of Nisin.The protective effect lined from stronge to weak was as followed:chitosan>milk>trehalose>sucrose.5. The results of FTIR and DSC implicated that there were strong binding between （NaPO3）6, EDTA, chitosan, trehalose and Nisin molecules, which resulted in the stabilizationof the structure of Nisin and the improvement of thermal stability of Nisin.6. The results of RSM showed that Nisin and EDTA had a significant effect on TVB-Nof cooked chichen wing（P<0.05）, and TP had a extremely significant effect（P<0.01）. Nisinand EDTA had a significant interactive effect on TVB-N （P<0.05）. Nisin and EDTA, chitosanand TP, chitosan and EDTA had significant interactive effects on colony count （P<0.05）,while interactive effects amone other biopreservatives were not significant. The optimumconcentrations of Nisin, chitosan, TP and EDTA in the compounding formula were0.20%,0.21%,0.15%,0.20%, respectively.7. When cooked chicken wings were coated with the aforementioned compoundingpreservatives and followed by thermal sterilization, the growth of microorganisms could beinhibited markedly and the shelf life was prolonged efficiently, and the quality of productskept good.