Microflora Changes Of Hot-Boned Pork During Storage And Establishment Of Predictive Model Of Enterobacteriaceae

Hot-boned pork remaining warm conditions is usually sold in food market after slaughter in early morning. The hot-boned pork mostly comes from small workshop which has poor sanitary conditions causing pollution to the pork. In addition, ambient temperature has a great effect on hot-boned pork, especially in summer, and the mircoorganisms in the pork grow up quickly due to the high temperature. However, there are still more than half of the consumers preferring hot-boned pork. Therefore the safety problem of hot-boned pork has attracted more and more attention. Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) was used to quickly and comprehensively study the microflora changes in hot-boned pork during storage. Recently, predictive microbiology has been a rapid and effective method to evaluate the shelf life and the quality of the pork. In this study, the microflora changes and the dominant microorganisms in hot-boned pork were investigated by traditional bacterial cultivation and PCR-DGGE. The predictive growth model of Enterobacteriaceae in hot-boned pork was built, providing scientific basis for the quality control and safety management during the sales process. The contents and results were detailed as follows.1. The hot-boned pork was fetched one hour after slaughter. After stored at5℃,15℃,25℃and30℃for some time, hot-boned pork was subjected to the total aerobic counts (TAC). Results showed that the TAC increased with the storage time extending. And it took about14d,75h,19h and16h for the TAC of hot-boned pork stored at5℃,15℃,25℃and30℃respectively to reach the minimum spoilage amount7.2lg(CFU/g).2. PCR-DGGE was used to study the microflora changes in hot-boned pork during5℃,15℃,25℃and30℃storage. Results of PCR-DGGE showed that it had a higher profile similarity in the later stage of the storage process. The diversity of original microflora of different temperatures was nearly the same and the dominant microorganisms were Macrococcu sp., klebsiella sp., Citrobacter sp., Enterobacteriaceae. The predominant bacteria of hot-boned pork stored under different temperatures were changed at the end of the monitoring. After comprehensive analysis combining the conditions of different temperatures, we conclude that the dominant bacteria of hot-boned pork included Enterobacteriaceae, Macrococcu sp., Acinetobacter sp., Aeromonas sp..3. The aseptic hot-boned pork was inoculated with Enterobacteriaceae, put on aseptic plate and stored at5℃,10℃,15℃,25℃and30℃respectively. The dynamic growth model of Enterobacteriaceae was established and verified. SPSS software was used to fit the status of growth at different temperatures. The results indicate that modified Gompertz could well describe the growth of Enterobacteriaceae in hot-boned pork. The correlation regression of Belehradek model finely described the effect of temperatures on its μmax and lag. The validation of the built model was carried out by comparing the actual and predicted growth curves of Enterobacteriaceae in hot-boned pork at8℃and22℃respectively. Results indicate that the established model has high reliability and can predict growth of Enterobacteriaceae on hot-boned pork in the range of temperature from5℃to30effectively.