Investigated Yersinia Enterocolitica During Swine Slaughter And Established The Predictive Model

Yersinia enterocolitica was one kind of person and livestock pathogens which was main parasitism in healthy pig's throats. It infected the human through food ways and so on, causing human's food poisoning and posing the very big threat to the humanity. Starting with studing on the enrichment and isolation method, investigating prevalence and contamination status of Yersinia enterocolitica in different slaughter process. The growth tendency of Yersinia enterocolitica was predicted on mathematics model. The aim is to provide a theory basis and technique for the controlling strans during production process of chilled pork. The paper includes three parts:1. Study on the methods for isolation of Yersinia enterocolitica during the swine slaughterYersinia enterocolitica was isolated and identified from 216 pig throat samples colleted from the slaughterhourse. Two suitable enrichment methods of PBS and MM were used, the effect of enrichment and isolation of CIN-I,"Y" and MacConkey sagar for Yersinia enterocolitica were evaluated. The results showed that CIN were combined to isolate well and truly after enrichment for PBS at 26℃, 30±2h, and the method can improved the isolation rate of Yersinia enterocolitica during the pigs slaughter.2. Investigated and studied on Yersinia enterocolitica in the prosess of swine slaughterPrevalence and contamination status of Yersinia enterocolitica were investigated and studied in different slaughter process. The distribution status of biotype and serotype was confirmed. The result showed that altogether 22 strans of Yersinia enterocolitica were examined and these strans of the bacterium were shown to be of 0:3,0:8,0:9 serotype and biotype 2, 3. The tongues of healthy pigs are the most important reservoirfor Yersinia enterocolitica. The carcasses surface in different slaughter process were contaminated. Especially, the scalded process was most contaminated.3. Predictive of microbal growth kinetics model of Yersinia enterocolitica prediction in chilled porkYersinia enterocolitica was inoculated to no contamination longissimus muscle, then the samples were tray-packaged at 0,5,10 and 15℃. A series of experimenthad been carried out to develop and validate the growth kinetics model of Yersiniaenterocolitica. The kinetics model of Yersinia enterocolitica had been developped and the results showed growth dynamics of this organism in deferent temperature could be well described by a Gompertz type model. The temperature had no significant effect on lgN_max (maximum cell concentration), the average value of lgN_max was determined to be 9.259±0.83(cfu/g) under those four temperatures . The correlation regression showed could finely describe the influence of temperature on growth. Validation of built kinetic models was preferred by comparing with experimental development of Yersinia enterocolitica grown on chilled pork at temperatures 3℃, 8℃. Bias and accuracy factors were used as comparison indices which were 0. 92,0.97 and 1. 09,1. 04 , respectively. It suggested the growth kinetics model of Yersinia enterocolitica was developed more reliabilly.