Analysis Of Bacteria Diversity Changes And The Technology Research Of Drenching For Reducing Bacteria On The Surface Of Chicken Carcasses In Slaughtering Production Chain

In recent years, the chicken production have increased rapidly in China, our country had became the second largest producer of chicken. The chicken products have rich nutrition which provide good conditions for the microorganism growth, so we should ensure the safety of the chicken products during slaughter processing and reduce the microbial contamination in production chain. Therefore, the aim of this study was to analyze the impact of seven processing steps (plucking, evisceration, washing, chilling, splitting, freezing) on the specific microbial contamination and bacteria diversity changes, then researched of the drenching for reducing bacteria of chicken carcasses. The main results were as follows:1. The specific microbial contamination in chicken slaughtering production chainRefer to GB 4789.2-2010,GB 4789.3-2010, SN/T 1933.1-2007, GB 4789.4-2010, GB4789.10-2010, which analyze the specific microbial contamination in chicken slaughtering production chain. The aerobic plate counts, counts of coliforms, Enterococcus of chicken carcasses during slaughter processing respectively were 4.41-5.36,2.91-4.24,1.79-3.34(lgcfu/cm2), the detection rates of Staphylococcus aureus and Salmonella respectively were 37.50% and 12.75%. Thus, the specific microbial contamination of chicken carcasses and products was more serious in chicken slaughtering production chain.2. The impact of drenching to reduce bacteria on decontamination of chicken carcasses by using lactic acid combined with hot waterBy the uniform design experiment that using different concentrations of lactic acid combined with different temperature of the water drenched chicken carcasses by controlling the time, which resulted that the 5th group (water temperature was 50℃, 1.5% lactic acid, drenching time was 15s) was the best,which can reduce bacteria counts 1.998 (lgcfu/cm2), moreover, the colors of chicken carcasses almost had no change after treatment.3. The specific microbial contamination in chicken slaughtering production chain after the treatment for reducing bacteriaAfter reducing bacteria treatment, the specific microorganism on the surface of the chicken carcasses was significantly reduced, the aerobic plate counts had been reduced 0.59-1.47(lgcfu/cm2), There was significant difference between the two groups (P<0.05) in the washing and chilling steps, the specific microorganism had reduced 0.59(lgcfu/cm2) in both splitting and freezing steps, and there was no significant difference between the two groups in the two steps (P>0.05). Counts of coliforms had reduced 0.15-1.19(lgcfu/cm2), the difference between two groups was not significant (P>0.05) in every link. It was the most obvious that the counts of Enterococcus reducing in the washing step (0.73-0.92(lgcfu/cm2)), in addition to split link was no significant difference (P>0.05), the rest of the links was significant difference (P<0.05). The frozen products of staphylococcus aureus and salmonella detection rates were significantly reduced to 9.76% and 1.22% respectively.4. PCR-DGGE analysis bacteria diversity changes before and after the treatment for reducing bacteria in chicken slaughtering production chainBy PCR-DGGE technique analysis bacteria diversity changes before and af ter the reducing bacteria treatment in chicken slaughtering production chain, the results showd that there were Lactobacillus, Uncultured bacterium, Enterobacte riaceae bacterium, Uncultured Clostridiales bacterium, Ruminococcus, Pseudomo nas sp., Pseudomonas fluorescens, Uncultured Pseudomonas sp. and Uncultured Ruminococcus sp. on the surface of the chicken carcasses, the amount and type of bacteria in washing step were the most, while in chilling step were the leas t. After reducing bacteria treatment, the bacterial species in chicken slaughterin g production chain had reduced about 4-6 kinds, such as Uncultured bacterium, Uncultured Clostridiales bacterium, Pseudomonas fluorescens, Ruminococcus and Uncultured Ruminococcus sp. After processing bands some gel intensity of corr esponding to the production decreased significantly, which illustrated the amoun t of bacteria in each link also had a certain degree of reduced.5. Changes in the chemical and sensory properties of chicken products before and after the treatment for reducing bacteriaThe first two months of storage period, the treatment for reducing bacteria had a little impact on chemical and sensory properties, the products quality was slightly better after treatment than before, the physical and chemical properties of two groups products conformed to the 《GB 16869-2005 fresh and frozen poultry product》 for demanding of frozen poultry products. By DGGE profiles, the microbial communities of quick-frozen products had significantly decreased after treatment, This may be the reason that the sensory quality of chicken products after treatment was slightly better than before, and total volatile basic nitrogen of chicken products after the treatment rose more slowly than before.This paper analyzed the specific microbial contamination, the diversity and change rules of bacteria, and the influence of the microbial on the surface of chicken carcasses and products by drenching. The results not only can provide reference for the improvement of products safety for the enterprises, but also provide theoretical basis and practical guiding significance for improving chicken slaughtering production process, and strengthen the quality control in chicken production chain. Thesis conclusion had certain theoretical significance and practical value.