| Chilled chicken has rich nutrients,and it's convenient and safe.However,due to its high protein,high moisture and other characteristics,chilled chicken is vulnerable to microbial contamination,affecting the shelf life of products and even causing adverse effects on human health.Thus,it is important to extend the shelf life of chilled chicken by using new packaging technology for antibacterial preservation.Nowadays,the antibacterial packaging in China is mostly polymer loaded with chemical antibacterial agents.Therefore,this work aimed to study the natural macromolecular materials loaded with natural antibacterial agents prepared by electrospinning technology,based on the antibacterial effect of the materials on conditional pathogens in chilled yellow feather chicken,and to explore the preservation effect of antibacterial packaging film on chilled chicken breast.This work enriches a research basis for the preparation of antibacterial nano-materials,and provides a guidance and ideas for the practical application of natural antibacterial food packaging.The main research contents and results are as follows:In this study,contamination of pathogenic bacteria was investigated in different seasons of chilled yellow feathered chicken.The results showed that most of the 78 strains were Enterobacteriaceae,and the number of opportunistic bacteria in summer accounted for 57.7% of the total.It indicated that summer was more easily to cause pollution than the other three seasons in the process of chicken slaughtering,transportation and storage.Escherichia coli was the main opportunistic pathogen in chilled yellow feathered chicken,which was accounted for 30.8% of the total strains.The forming film ability of opportunistic pathogen was for further analyzed,and then six strains were selected as the target strains for the study of natural antimicrobial food packaging.In order to prepare natural antimicrobial food packaging,gelatin and chitosan were used as carriers to load ?-polylysine and 3-phenyllactic acid by electrospinning technology.The electrospinning nanofiber membrane had a good properties good fiber morphology chemical structure and thermal stability when the ratio of gelatin/chitosan was 6:1 or 8:1,implying it can be used as the carrier of electrospinning blend and loaded with different natural antibacterial agents,which can be obtained more stable electrospinning nanofiber membrane and significantly enhanced the antibacterial activity.In order to clarify the application of gelatin and chitosan as antibacterial packaging carrier,gelatin/chitosan/?-polylysine nanofiber antibacterial film was prepared.The physicochemical properties and antibacterial effect of the film were characterized with the nano antibacterial film.The results of chemical analysis showed that the viscosity of the blends decreased,and the electrical conductivity increased with the addition of poly(L-lysine).The results of chemical analysis showed that the polymer chains were formed successfully,but no new substances were formed.The thermal stability of the nanofiber membrane was greatly improved by the addition of ?-polylysine.The antibacterial effect of the film was further characterized.It was found that when the ratio of gelatin to chitosan was 6:1 and the amount of ?-polylysine was 1.5 mg / m L,the electrospun nano antibacterial film could kill 5 log CFU / m L opportunistic bacteria.In order to obtain nano antibacterial film with higher antibacterial activity and more stable properties,3-phenyllactic acid was added into gelatin/chitosan blend to enhance the antibacterial activity of nano fiber film and change the properties of the blend.The physicochemical properties and antibacterial effect of the nano antibacterial film were characterized.It was found that the carboxyl group in 3-phenyllactic acid could react with the amino group in chitosan to form amide bond,which increased the solubility of chitosan in the blend and reduced the viscosity of the blend.The antibacterial test shows that the uniform and dense network structure of the nano antibacterial film makes the film have the best antibacterial effect when the amount of 3-phenyllactic acid is 2%.In order to determine the practical application effect of the electrospinning antibacterial film,the electrospinning antibacterial film wrapped the chilled chicken breast and observed the quality changes of chicken breast during storage Compared with the other two groups,the color and p H of the films did not change significantly(P > 0.5),and the content of volatile basic nitrogen increased slowly.The results of microbial analysis showed that the two films could extend the storage period of chicken breast meat through the growth of microorganisms,especially proteus.The results of this study showed that the nano antibacterial film,prepared by using gelatin and chitosan as carriers and electrospinning technology loaded with ?-polylysine and 3-phenyllactic acid,had a strong bactericidal effect on microorganisms in chilled chicken.Meanwhile,it has no adverse effect on the quality of chicken,which provided a theoretical basis for the development and application of edible nano antibacterial film. |
PDF Full Text Request