Research On The Properties Of Sustained Release And Bacteriostatic Of Antimicrobial Coating Containing Nisin And Sodium Lactate

Active packaging is a new type of packaging technology.antimicrobial coating packaging is one of the promising aspects. The study of antimicrobial coating film whether it could play a role in inhibition of bacteria has significate meaning on protecting the quality of inner products and extending shelf-life. This article studies three aspects on this film as following:(1) The research of diffusion of Nisin.Chitosan was chosen as a carrier material. First of all, the factors which effected the diffusion of Nisin from chitosan were studied.From the process conditions, the orthogonal experimental was designed with four factors, such as chitosan-glycerol ratio, the volume of water, the thickness of coating and temperature. The thickness of coating was the primary factor which affected diffusion coefficient, and the best combination was obtained to make the diffusion coefficient maximal which was chitosan-glycerol 2:1, 100ml water, coated 0.7mm, storing at 25℃.Based on it,the study was shown that the thicker of coating and higher of chitosan-glycerol ratio,the larger diffusion coefficient of antimicrobial coating containing Nisin. The diffusion coefficient was determined at different temperatures, and the activation energy of Nisin in this coating was obtained. In addition, the different food simulation and initial volume of Nisin could affect the diffusion coefficient.2% sucrose,2% sodium chloride and water represented different types of food. The diffusion coefficient of Nisin was the largest in 2% sucrose solution by comparison, followed by water and sodium chloride solution. Different amounts of Nisin were added into this antimicrobial coating, the initial amount of Nisin was not present a law which effected on the diffusion coefficient, but impacted the balanced time mainly. The more initial amount, the sooner to reach equilibrium.(2) Inhibition research. The inhibit effection of Nisin and sodium lactate on specific bacterium was studied in this part. Bacillus suntilis and E.coli was chose according to the characteristics of antimicrobial agents. The inhibit effection of different concentration gradient of antimicrobial agents on these two bacteria was measured, and the conclusion was as following: the greater the concentration of antimicrobial agent, the stronger the inhibition of bacteria, in particular, when the concentration of Nisin of 320μg/ml could be completely inhibited the growth of Bacillus subtilis.(3) Applications. The above antimicrobial coating film applied to pasteurization milk/coconut milk. The total number of colonies in milk/coconut milk was measured at different time by the method of bacteria coating. The result was that the coating which contained Nisin and sodium lactate was showed best inhibition than that contained one antimicrobial agent and no antimicrobial agent.