Research On Fresh-Keeping Eggs By Coating Packaging

The research on adopting natural antibacterial agents and the edible raw material WPC to make film solution which was coated on the eggs surface, in order to reduce moisture evaporating and microbial growth, extending the shelf life of the eggs.First of all, determined the antibacterial activity of the nine natural antibacterial agent through the filter paper dispersion, the result showed that the ε-polylysine, Nisin, egg white lysozyme and thyme essential oils haved a strong inhibitory effect on the main pathogenic bacteria of eggs which were staphylococcus aureus, Escherichia coli and salmonella. The experimentation on the mixture lysozyme, Nisin and thyme essential oils with s-polylysine was discussed. Analysised the joint bacteriostatic effect of the three kinds of bacrerium. According the graded inhibitory concentration index performance evaluation showed that the best inhibitory effect was when the ratio of Nisin:s-polylysine=1:1or thyme essential oils (uL):s-polylysine (mg)=24:1.Making the qualitative and quantitative analysis of the main component of thyme essential oil by Gas Chromatography-Mass Spectrometry (GC-MS), the result showed that the main component of thyme essential oil was thymol and carvacrol which absolute content were 155.8815mg/ml,28.9771mg/ml. determined the bacteriostatic effect of ε-polylysine, Nisin and thyme oil at different temperatures, pH values and different illumination time by spectrophotometry. The result showed that the antibacterial effect of ε-polylysine was stable in various environments,while Nisin was sensitive with pH values,thyme essential oil followed.Gained influence data on the barrier properties and mechanical properties of whey protein concentrate film with different concentration of whey protein concentrate, plasticizer glycerol,reducing agent anhydrous Na2SO3 and crosslinking agent transglutaminase(TG) by single factor experiment; then maked orthogonal test,analysis derived that barrier properties of the best group of whey protein concentrate film formulation consisting was 11% whey protein concentrate,4% glycerol,0.1% anhydrous Na2SO3,0.1% TG by orthogonal array L9(34),Which was made coating solution for eggs preservation.The eggs by coating were stored in the temperature of 28℃,20℃; the humidity conditions of 60%-80%. The effect was studied by the determination of sensory evaluation, weight loss, yolk iedex, Haugh unit, egg-white pH values,volatile basic nitrogen, coloniesthe total number of main indicators, the result showed that the optimum coating liquid formulations added preservative 1.0mg/ml ε-polylysine+1mg/ml Nisin was the best preservation effect.In 28℃、20℃,for Haugh unit,, the result showed that in AA grade,the shelf life ofblank group were 5d,7d respectively., the shelf life of the third group were 17d,31d respectively, the shelf life of fresh eggs were extend significantly.