Isolation,Identification Of The Predominant Spoilage Bacteria And Bacteriostasis In The The MAP Pot-Stewed Duck Esophagus

The duck esophagus,which is also known as the “Ya Jun Ba” and “the duck pancreas stomach”,is located at the joint of the duck gizzard and the duck food bag.It is one of the traditional Chinese food materials.The modified atmosphere packaging(MAP)pot-Stewed duck esophagus produced by Harbin Yuchang Food Co.,Ltd.is a kind of low-temperature meat product.Because of its low processing temperature,production environment and other reasons,it is easy to be polluted by spoilage bacteria and has a short shelf life.Short shelf life is not conducive to product transportation and sales,so how to improve product shelf life is an urgent problem.In this paper,through the separation and identification of the dominant spoilage bacteria in the MAP pot-Stewed duck esophagus of Yuchang air-conditioned in Harbin,the dominant spoilage bacteria in the MAP pot-Stewed duck esophagus were screened out,and the corresponding antibacterial agents were compounded according to the detected spoilage bacteria to provide theoretical support for prolonging the shelf life of Yuchang MAP potStewed duck esophagus.In order to study the storage quality and the change of bacterial phase of the MAP potStewed duck esophagus at 4 ?.The storage of the MAP pot-Stewed duck esophagus without bacteriostatic agent or bactericidal treatment for 1~12 d at 4 ? was carried out.The changes of pH,water activity,TBARS,color difference and sensory quality with storage time were measured.The results showed that with the prolongation of storage time,the sensory quality,pH value,TBARS value,water activity and a * and L * value of the MAP pot-Stewed duck esophagus decreased significantly,while TBARS value and B * value did not change significantly.The traditional plate culture method was used to study the changes of the bacterial phase and the total number of colonies of the MAP pot-Stewed duck esophagus.At4 ?,the colony number of mould,anaerobic bacteria,yeast,Escherichia coli,thermophilic bacteria,lactic acid bacteria,Pseudomonas,Enterobacter,Enterococcus,Staphylococcus and Bacillus in the MAP pot-Stewed duck esophagus showed an obvious upward trend,and the total number of microbial colonies increased with the increase of storage time.The shelf life ofthe MAP pot-Stewed duck esophagus was 7d at 4 ?,the quality began to deteriorate at the 8th day of storage,and completely rotted at the 12 th day.Plate culture method and 16 S rDNA sequencing and bioinformatic analyses were used to isolate and identify the dominant spoilage bacteria in the oesophagus of the MAP pot-Stewed duck esophagus stored at 4 ? for 1d,8d and 12 d respectively.277 strains of bacteria were cultured in the MAP pot-Stewed duck esophagus stored at 4 ? for 1d,8d and 12 d,and 6strains of dominant spoilage bacteria were screened through colony morphology,bacterial morphology and some physiological and biochemical identification.Six strains of putrefactive bacteria were sequenced with 16 S rDNA gene,and phylogenetic trees were constructed after sequence comparison.The results showed that 39% of the six strains were Bacillus tequilensis,23% were Enterobacter xiangfangensis,21% were Klebsiella granulomatis,11% were Pseudomonas parafulva,11% were Enterobacter ludwigii and Klebsiella variicola accounted for 5% and 1% respectively.Therefore,the predominant spoilage bacteria in the airconditioned packaging sauce duck esophagus are Bacillus tekilla,Enterobacter xiangfang and Klebsiella granuloma.Six antimicrobial agents(nisin,?-polylysine,tea polyphenol,potassium sorbate,sodium diacetate,sodium dehydroacetate)were used to study the bacteriostatic effect of three selected target bacteria(Bacillus tekilla,Enterobacter xiangfang,Klebsiella granulomatosis).The better bacteriostatic agent was selected for compounding.By response surface experiment,the best formulation of antibacterial agent is ?-polylysine 0.05 g/kg,nisin 0.2 g/kg,tea polyphenol0.12 g/kg.The analysis of physical and chemical indexes,sensory indexes and the total number of colonies showed that the shelf life of the product stored at 4 ? with compound antimicrobial agent and compound antimicrobial agent was longer than that of the sample without compound antimicrobial agent for 5 days,reaching 12 days.