Preparation And Application Of An Antimicrobial Packaging Film For Food With Controlled Release

The antibacterial activity of the antibacterial film and the slow release of the antibacterial agent can not achieve the ideal antibacterial effect.Intelligent antimicrobial packaging technology can achieve the release of antimicrobial agents on demand and it is the future direction of the development on food packaging industry.This paper was based on the law that ?food spoilage starts from the surface and along with the decrease of pH?,using the acid sensitive characteristics of Schiff base,f?using on the food surface that has most prone to spoilage,the experiment designed a new kind of nano packaging film that could both sense the mediun pH signal and realize the dynamic regulation for the release of the antibacterial agent.The particle size tunable aldehyde containing nano particles were obtained by emulsion polymerization and self-assembly technique.In order to obtain the intelligent nano packaging film by using the Schiff base coupling high effective antibacterial agent,the tape was dispersed in the compatible membrane material,and its application effect was further discussed.The project intends to achieve the dual goals of ?active? and ?intelligent? for food packaging film,and it will provide a new reference for China's food packaging industry technology upgrades.The main contents of this paper are as follows:(1)At 85 ?,with St as core monomers,VBA as shell monomers,APS as initiator,DNS458 as emulsifier,AMA as crosslinking agent,by the methods of pre emulsification and emulsion polymerization,the aldehyde group containing nano polymer microsphere with core-shell structure was synthesized.TEM showed that the morphology was spherical,the size was uniform,and the particle size was 50-60 nm.The particle size distribution showed a typical Gauss distribution and good dispersion.Using Nisin as the model antibacterial agent,the microspheres were prepared by coupling Nisin loaded with Schiff bases and Nisin-conjugates containing aldehyde groups were obtained.Bradford method was used to measure the load rate of ninety-five percent.TEM showed that the particle size was 80-100 nm.(2)PVA were prepared by melt casting method,which was used to introduce the nano particles of Nisin-containing aldehyde group and nan ? rystallize them to prepare antibacterial composite membrane film.The results showed that when the 250 mg conjugate was added to the poly PVA,the diameter of inhibition circle was 10nm;the modulus of elasticity was 2060.42 MPa,which is increased 8.5 times;ORT decreased from 2.835 cc/m2d0.1Mpa to 1.825 cc/m2 d 0.1Mpa;WVP decreased from 2.84 g mm/m2 day Kpa to 2.59 g mm/m2 day Kpa,the results above approved that the addition of the conjugate gave the film strong antibacterial properties,barrier properties and physical mechanical properties.In addition,when the pH was 2 and 7,the release of antibacterial at 100 h were 53.0% and 12.4%,showing that the release of antibacterial agent was pH responsive.The release of Nisin from different food simulants showed that Nisin had a large amount release in acidic food and fat food,and it was less in salty and sweet foods.Finally,with the increase of the amount of the conjugate,the change of three stimulus value and color coordinate showed that the red and yellow values of the composite film increased,but the witheness and transparency decreased.(3)The fresh pork were randomly divided into three groups,the group was treated with PVA membrane and antibacterial membrand,and the other group was not treated as blank control.The three groups of meat were placed in a constant temperature of 22?,Sensory evaluation,weight loss rate,total number of bacteria and TVB-N were determined everyday,the results showed that the antibacterial composite film had good preservation ability to pork,and could maintain the first frade fressness of meat for 3 days and the second frade freshness of meat for three days.