Antibacterial Properties Of ε-poly Lysine And Its Effects On The Preservation Of Fresh Pork

Epsilon-poly-lysine is a kind of cationic polymerization peptides. As a kindof natural nutritional type biological preservative, ε-PL not only has good antibacterialeffect, wide antibacterial spectrum, good inhibitory effect to yeast, mold, gram-positive,gram-negative bacteria and phages, but also has the characteristics of high temperatureresistant, non-toxic side effects to the human body. The antibacterial properties andcharacteristics of ε-PL make it used in food preservation preservative and has goodapplication prospect. In this paper, the physical and chemical properties, security ofε-PL was introduced, and antibacterial effect of ε-PL to Escherichia coli, S.aureus andB.subtilis, mechanism and preservation effect of chilled meat were researched. Mainresults were as follows:(1) Antimicrobial activity of ε-PL against B. subtilis, E coil and S. aureuswas determined through Oxford cup method and the minimum bacteriostasisconcentration was determined by the method of colony count. The results showed thatε-PL had antimicrobial activity against B. subtilis, E coil and S. aureu. Theantimicrobial activity of ε-PL against three bacterium was S. aureus＞B. subtilis≥Ecoil. The antimicrobial activity of Gram-positive S. aureus was significantly better thanGram-negative B. subtilis and E coil. And the antimicrobial activity increased with theincrease of ε-PL concentration. The minimum inhibitory concentration (MIC) of ε-PLagainst three tested bacteria was all12.5μg/ml.(2) To search for possible inhibitory mechanisms of ε-PL on B. subtilis, Ecoil and S. aureus, SEM was performed by observing bacteria cell surface morphology.The results indicated that ε-PL significantly destroyed B. subtilis, E coil and S.aureus.To search for possible cellular leakage mechanisms of action of ε-PL on B.subtilis, E coil and S. aureus, Electrical conductivity was performed on bacteria treatedwith ε-PL. ε-PL caused bacteria cell membrane damage and electrolyte leakage fromthe bacteria cells. SDS-PAGE protein electrophoresis experiment indicated ε-PL hadsignificant influence on protein of S. aureus.(3) Total bacterial counts, total volatile basic nitrogen value (TVB-N) and pH,high ironmyoglobin, and sensory functions was tested as an indicator to study thechanges in the quality of chilled pork during storage after the treatting with differentconcentration ε-PL.These results showed that ε-PL could effectively inhibit bacterial growth, reduce the value of TVB-N, high-iron myoglobin and pH, and stablethe of color under refrigerated conditions for about4℃. Optimal preservation effect ofchilled pork was1.25%and1.5%ε-PL; it could extend the shelf life of chilled pork to7days. These results demonstrate that ε-PL had extensive application prospects as abiological fresh-keeping agent for chilled pork.(4) The texture influence of meat by ε-PL was determined. The result showedthat ε-PL had effect on the hardness and shear force of meat, but the effect was notsignificant. Overall, the optimum of low hardness meat production was:0.75%of ε-PL,water bath60min, room temperature. In order to produce low shear force of meat, theoptimum conditions was:1.00%of ε-PL, water bath60min, room temperature. Toreduce the cooking loss of meat,1.50%ε-PL should be added.