Fungus Contamination Of Eggs In Southern Hebei And Preparation Of Antibacterial Fresh-keeping Film

Eggs are animal-derived foods rich in a variety of nutrients,but they are prone to deterioration.The most common factor is contamination by bacteria,in which fungi are also an important source of pollution.However,there is little research on fungal pollution of eggs in China.Therefore,for the detection of fungal contamination of eggs,the research and preparation of effective antibacterial coating antistaling agents is of great significance for improving the egg quality and economic value of eggs.Under two different storage conditions(25°C and 4°C,relative humidity50%-60%),the quality changes of eggs in Southern Hebei were studied.After comparing the quality of eggs under different temperature conditions,all indexes of eggs stored at 4°C were better than those stored at 25°C.After analysis,it is concluded that the shelf life of eggs under the two temperature conditions is different.The shelf life of eggs is about 30 days under 25°C storage conditions.The shelf life of eggs can be extended to 40 days under 4°C storage conditions.In these egg samples,a total of 168 isolated strains were isolated,and 132 strains of filamentous fungi were obtained through the combination of morphological observation and gene sequencing(46 strains of Penicillium,29 strains of Aspergillus,18strains of Fusarium,10 strains of Trichoderma,29 others)36 strains of Yeast like fungi.The dominant species of egg-derived fungi are Penicillium oxalicum,Talaromyces verruculosus and Candida parapsilosis.the dominant genera are Penicillium sp.,Talaromyces sp.and Aspergillus sp..These fungi will accelerate the deterioration of eggs,and even risk infection and disease.After analysis,the establishment of a phylogenetic tree of egg-derived fungal flora provides a basis for the prevention and control of egg fungal contamination.The antagonistic strain A4 with the strongest antibacterial ability was isolated from the fermented feed samples obtained from the chicken farm.It was identified that the antagonistic strain A4 is Bacillus subtilis,which has a strong antibacterial effect on the dominant fungi with serious egg pollution.It shows that the use of Bacillus subtilis to prevent and control the internal and external bacterial pollution of eggs has commercial value.Using chitosan,glacial acetic acid and sterile fermentation filtrate of Bacillus subtilis as raw materials,antibacterial preservative was developed.The concentration of the other three substances was optimized with the membrane moisture permeability as the main index.Based on the single factor test,the response surface test was designed,and the optimal ratio was calculated as follows:chitosan 3.0%,glacial acetic acid 2.0%,sterile fermentation broth 2.0%.Under the optimized conditions,the moisture permeability of chitosan glacial acetic acid sterile fermentation filtrate composite membrane was the lowest,465.207 g/m~2·24 h,which provided a new idea for the study of antibacterial and fresh-keeping of eggs.Chitosan glacial acetic acid aseptic fermentation broth antibacterial fresh-keeping solution was coated on the surface of eggs.The egg quality indexes of the coating group were significantly better than those of the washing group and the control group.The results showed that this composite coating method could effectively prevent the increase of egg Weight Loss(P<0.01),delay the decrease of Haugh Unit(P<0.05)and egg Yolk Index(P<0.05),maintain the normal p H Value(P<0.05),and prolong the shelf life of eggs from about 30 days(control group,water washing group)and 40 days(refrigeration group)to about 90 days(coating group),It has good bacteriostatic and fresh-keeping effect on eggs,and improves the economic value and food safety of eggs.In summary,this experiment analyzed the law and reasons of egg quality changes in Southern Hebei,and recognized the number and species of egg-derived fungi.Through the antagonistic bacteria(Bacillus subtilis)isolated from the fermented feed samples of chicken farms,the use of Bacillus subtilis Bacillus bacteria aseptic fermentation filtrate,chitosan and glacial acetic acid are combined to prepare antibacterial coating and fresh-keeping agent for eggs.The results showed that the composite coating of chitosan glacial acetic acid sterile fermentation filtrate could prolong the quality,freshness and preservation period of eggs,improve the food safety of eggs,provide reference data for the economic value of eggs in Southern Hebei new area,and improve the economic value of eggs.