The Application Of Compound Preservative In Pickles

Pickles is a common side dish on the residents’ table, the flavor is very popular, but the vegetables with high water content, nutritious, susceptible to microbial contamination.Pickles in the market often added chemical preservatives while appeared excessive additions.Finally lead to food safety issues. The production of the biological process of food preservatives may eliminate the harm, but the high cost of biological preservatives, is restricted in the practical application. In order to reduce the cost, this paper chooses several kinds of safe and efficient biological preservative to study the application on pickles.Five species of bacteria and six species of fungi were obtained from pickled vegetables after a preliminary separation and purification. By colony counting, it is confirmed that bacteria were the main microorganism that resulted in the spoilage of pickles. Meanwhile,the dominating bacteria included Bacillus megaterium, Bacillus subtilis, Bacillus cereus,Bacillus thuringiensis and Bacillus cereus, among which Bacillus subtilis and Bacillus thuringiensis were in the majority.The antibacterial test showed that the spoilage bacteria could be completely inhibited at the concentration of 8-PL 60 μg/mL, Nisin 60 μg/mL, tea polyphenols (TP) 400 μg/mL and chitosan 75 μg/mL, respectively. Besides, the spoilage fungi could be completely inhibit at the concentration of Natamycin 40 μg/mL. The FIC (fractional inhibitory concentration) test showed that synergetic application of the ε-PL, Nisin and tea polyphenols could enhance theantibacterial effect, while there would be a antagonism effect when the chitosan and tea polyphenols were employed together. ε-PL, Nisin. and tea polyphenols can reduce the adhesion of bacteria and formed a concentration dependent effect. The inhibition effect of ε-PL, Nisin and tea polyphenols to the adhesion rate were most obvious, and in this circumstance the adhesion rate of mixed bacteria decreased by 76.8%, 72.2% and 60.2%,respectively.In order to determinate content of the different components in the preservative, the response surface was conducted, and their final concentrations were ascertained to be: ε-PL 0.06 g/kg, Nisin 0.06 g/kg, Natamycin 0.035 g/kg, and tea polyphenol was 0.40 g/kg,respectively.Pickles could be preserved for about 21 d at 37 ℃ by adding preservatives during its manufacture procession. The ultimate total number of microorganism colonies were 4.4x 103 CFU/g and the number of E.coli were 204 CFU/g after 21 d of storage, respectively.Physical and chemical indicators are in line with national standards, which provided reference for the application of s-PL in corrosion protection of pickles.