Isolation And Identification Of Specific Spoilage Organisms In Porcine Patties And Establishment Of Shelf Life Prediction Model

Pork Patties are welcomed by consumers because of their convenient use,nutrient hygiene,and tender and delicious taste.However,if the storage temperature is not properly controlled,the porcine patties are highly susceptible to spoilage and the shelf life is shortened.It is predicted that food microbiology can quickly and effectively predict the shelf life of foods through microbial growth characteristics to ensure food safety.In this study,the porcine patties were used as test materials to isolate and identify specific Spoilage Organisms at the end of ice temperature storage and to establish a shelf life prediction model for dominant rot fungi.The main research contents and results are as follows:1.Store the vacuum-packed porcine patties under ice temperature conditions,isolate and identify all kinds of SSO by selective medium in the storage end point of the porcine patties,and the SSO of ice-temperature storage and porcine patties was identified by means of separation and purification,16S rDNA sequence analysis.The results showed that the SSO of the porcine patties were Lactobacillus sakei strain M3,Hafnia sp C5,Proteus sp C8,Enterobacteriaceae bacterium V6 and Obesumbacterium proteus strain V2.2.The specific spoilage bacteria were inoculated into bioclean porcine patties and stored at ice temperature with vacuum packaged.sensory scores,the total viable count(TVC),TBARS value,Total volatile base nitrogen(TVB-N),chromatism and bioamine were measured at different storage days,and quantitatively describe the spoilage ability of different SSO in porcine patties with YTVB-N/CFU.The results showed that the septic ability of Lactobacillus sakei strain M3 was strong,which was determined to be the dominant rot fungus of the patties under ice storage conditions.3.In order to understand the effect of SSO on the degree of oxidation of myofibrillar protein in the porcine patties,the specific spoilage bacteria were inoculated into bioclean porcine patties and stored at ice temperature with vacuum packaged.The the total sulfhydryl content,carbonyl content,protein solubility,Ca2+-ATPase activity and surface hydrophobicity were measured at different storage days,and the degree of protein oxidation and polymerization was analyzed by SDS-PAGE electrophoresis.The results showed that V6 and C8 had a great influence on the total sulfhydryl content;The C5 and M3 strains had a greater influence on the carbonyl content,and V2,C5,M3 have a greater influence on surface hydrophobicity,V6 and V2 have a great influence on Ca2+-ATPase activity and can promote protein polymerization.Comprehensive analysis shows that specific spoilage organisms can promote the oxidation of myofibrillar protein,and the ability of V2,C5 and M3 is stronger.4.M3 was inoculated into the bioclean porcine patties and vacuum packed at-1℃,4℃,9℃,14℃ and 20 C,the total viable count(TVC)were measured at different storage days.The modified Gompertz model,Baranyi and Roberts model and Logistic model were used to establish a shelf model of the porcine patties.The results show that the logistic model can better fit the growth dynamics of microorganisms at different storage temperatures.The shelf life prediction model of the porcine patties at the storage temperature range of-1℃ to 20℃ is SL=1/(0.0283T+0.9874)2-[8.34-lgN0/2.718×(0.02T+0.9224)2]×{ln[-ln(6.54-lgN0)/8.34-lgN0)]-1}...