Epidemiological Investigation And Reduce Technology Of Salmonella In Table Eggs And Egg Products

Food safety concerns the national economy and people's livelihood.China is a most country of eggs production and consumer in the world.Eggs and egg products play important role in the dietary structure in China.Salmonella is a common food borne pathogen,especially relevant with contaminated eggs.Salmonella contamination of eggs includes horizontal and vertical contamination.Horizontal contamination means that after laying eggs,the surface of the eggshell is contaminated by Salmonella and penetrates through the shell membrane barrier and penetrates into the interior of the egg.Rapid and accurate detection of Salmonella in eggs and egg products is necessary and effective to ensure the safety of egg production and egg consumption.Prevention and control before sales is important for risk control from farm to table,which can effectively prevent the outbreak of Salmonella disease related to eggs and egg products.In this study,a method for the isolation of Salmonella from eggs and egg products was established to investigate the prevalence of Salmonella in eggs and egg products of Jiangsu province.Based on the epidemiological survey data,the feasible prevention and control measures for Salmonella contamination from eggs and egg products were proposed.1.Isolation,identification and characterization of Salmonella in eggs and egg productsmTSB enrichment RVR10 selective enrichment and XLT4 differential culture method was established for Salmonella separation from eggs and egg products.1264 samples of eggs and egg products in the sectors of production and sales were collected from 5 cities and counties in jiangsu to investigate the prevalence of Salmonella since September 2016 to October 2018.100 strains of salmonella were isolated with a positive rate of 7.91%.Liquid egg products Salmonella separation rate was significantly higher than that in fresh eggs.Five serotype were identified from the Salmonella isolates,including Enteritidis?Typhimurium?Pullorosis?Munich and Uganda.Antimicrobial Susceptibility test results showed that the isolates generally resistant to nalidixic acid tetracycline antibiotics such as streptomycin and ampicillin,of gentamicin kanamycin and cefazolin sensitive antibiotics.MLST analysis of 46 isolated strains can be divided into 5 ST types,including ST11(84%)?ST92(6.5%)?ST34(4.3%)?ST83(2.2%)and ST684(2.2%).The biofilm forming ability of the isolates was determined by the quantitative method of crystal violet,which showed that the biofilm forming ability of the isolates was generally strong.2.Study on the abatement technology of Salmonella on the surface of fresh eggsThe amount of Salmonella on the surface of egg shell is in direct proportion to the probability of contamination of the contents of egg.Egg-derived Salmonella isolates can form a dense biofilm on the surface of the eggshell.New nanomaterials P1 and P5 have an obvious effect on inhibiting the biofilm formation of Salmonella,and the inhibitory effect on the biofilm formation of Salmonella is concentration dependent.The use of P1 or P5 with concentration of 32?g/mL could not only inhibit the formation of biofilm by Salmonella on the surface of eggshell but also scavenge the biofilm.The elimination and control of foodborne pathogens by organic acid(lactic acid)is generally regarded as a safe and effective method.Spraying 2%lactic acid on the surface of the eggshell can effectively reduce the level of salmonella contamination.Agar egg model,according to the results of Salmonella can through the eggshells,lactic acid spray egg penetrate more easily than the untreated egg.But on the whole egg permeability evaluation model,there was no significant difference(P>0.05)of Salmonella separation rate for 4? storage of lactic acid between the treatment group and control group.The data of determination of egg quality indexes showed that the Haugh unit,albumin pH and egg shell strength and thickness of lactic acid sprayed eggs and washed eggs were basically the same.Lactic acid treatment reduced the strength and cuticle integrity of eggshell.Cryopreservation helps prevent the re-contamination of lactic acid sprayed eggs.The results of this chapter lay a scientific foundation for studying the reduction of Salmonella on the surface of fresh eggs.3.Research on low temperature sterilization of egg productsMost eggs used for egg products processing is fresh eggs without treatment,easy to cause bacteria invasion and cross contamination to liquid eggs.The egg white contains lysozyme,vitamin chelating egg protein transferrin,antimicrobial peptides,and the characteristics of thick alkalescence,which can effectively inhibit or kill bacteria in eggs.Artificial pollution test found that egg white showed antimicrobial activity to Salmonella under the condition of 45?.The survival number of Salmonella within the egg whites fell sharply from 2 h to 6 h with treatment of 45? and extreme lower than treated with 30? and 42?,indicating that 45? treatment can promote ability of egg white to kill Salmonella.Moreover,45? treatment showed better bactericidal effect than that of pasteurization according to the results of XLT4 and PCA CFU counting to Salmonella and other microbes in the egg whites.Totally,an effective low temperature sterilization method was set up to promote quality and safety of egg products.