Isolation And Identification Of Main Spoilage Bacteria In Eggs During Storage

Eggs are rich in protein,various amino acids,minerals,vitamins and other nutrients needed by the human body.Eggs are one of the natural nutrients.However,the rich nutrients of eggs are also the breeding ground for bacteria.The pathogenic bacteria of egg-borne infectious diseases,such as Salmonella,Escherichia coli O157: H7,Listeria monocytogenes,etc.can produce poisonous and harmful substances,cause food poisoning and bring harm to human health.The non-pathogenic spoilage bacteria such as Enterobacter,Enterococcus,Pseudomonas,etc.can change the food composition and reduce the nutritional value,direct edible value and processing application value of food.Basing on the analysis of bacterial diversity of metamorphic eggs,the main spoilage bacteria were isolated,screened and identified from metamorphic eggs.And the effect of spoilage bacteria on the quality of fresh eggs was studied.The aim was that lay a foundation for further study on the mechanism of spoilage bacteria and the control measures of spoilage bacteria during the storage of deteriorating eggs.(1)High throughput sequencing analysis of bacterial diversity showed that the bacteria in the samples of deteriorated egg contents belonged to Protectorate and Firestorms.There are 19 genera of bacteria,including Citrobacter,Serratia,Bacillus,Pseudomonas and ect.At the same time,there are some low relative abundance,it's contains Staphylococcus,Escherichia-Shigella,Carnobacterium,Arcobacter and ect.(2)190 typical colonies were isolated from deteriorated eggs by using multiple selective media and dilution plate separation.Casein transparent circle is Preliminary screening;the resieving is that detecting TVB-N and Hough unit of artificially contaminated eggs after 5 d,and then we can determine 3 main egg spoilage bacteria in the end.From morphological,physiological and biochemical characteristics,The identification results showed that 1 strain of Serratia marcescens P9 and the other two strains of G53 and G36 were Ewingella Americana or Serratia marcescens.(3)The fresh eggs were artificially contaminated by three strains and incubated at 37 ? for 10 days.The freshness and quality of eggs were determined.The results showed that the main spoilage bacteria in eggs led to the decrease of Huff's unit from 82.26 to below 30,the decrease of yolk index from 0.42,the increase of weight loss rate,the rise of pH before and after the release of yolk,the rise of chamber height from 3.95 mm to more than 15 mm of egg length,the increase of S-ovalbumin content,and the majority of N-ovalbumin in egg white.The changes of the above indicators proved that Serratia marcescens and Ewingella Americana affected the quality of eggs,resulting in a decrease in the freshness of eggs.P9(Serratia marcescens)has the greatest impact on egg quality.