Dissertation
Dissertation > Industrial Technology > Light industry,handicrafts > Food Industry > Slaughtering and meat processing industries > Basic science

Studies on Microbial Contamination and Microbial Decontamination of Chemical Substances of Fresh Chicken

Author SunYanYu
Tutor ZhouGuangHong
School Nanjing Agricultural College
Course Of Food Science
Keywords Fresh chicken Microbial contamination Chemical decontamination Dominant spoilage bacteria Preservation PCR-DGGE
CLC TS251.1
Type Master's thesis
Year 2011
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Fresh chicken,is the strict implementation of veterinary inspection and quarantine system, the carcass of slaughtered poultry processing for rapid cooling, so that the carcass temperature is quickly reduced to 0-4℃, and in the subsequent processing, distribution and sales process always keep 0-4℃. The processing of fresh chicken consume low energy and low cost, but selling price is high.lt has a bright prospect because of the advantages over frozen chicken on nutrition, flavor and sanitation. But the shelf life of fresh chicken is short.We concerns microbiological contamination of fresh chicken during a series of slaughtering, cutting, cold storage and transportation, take effective measures to reduce microbiological contamination, it is significante guarantee product safety and health and extend product shelf life.This study take samples from a large chicken slaughtering enterprise, Study on the microbial community structure of refrigerated storage of fresh chicken was studied by PCR amplification and denaturing gradient gel electrophorsis based 16S rDNA, and clearly know dominant spoilage bacteria. The number and types of microorganisms change during broiler slaughter processing,and determine the critical control points. Different chemical substances were used to inhibit dominant spoilage bacteria, to find a practical and effective chemical reduction formula.1. The microbial community structure of refrigerated storage of fresh chicken was studied by PCR amplification and denaturing gradient gel electrophorsis based 16S rDNA.Activated sludge samples were collect from both chicken breast and drumstick.The total DNA was extracted and 16S rDNA was amplified by universal primer, The mocrobial community structure was analyzed by denaturing gradient gel electrophoresis,compared with the traditional culture. The traditional culture showed that:dominnat spoilage bacteria there are no differences between chicken breast and drumstick,and two curves changing trends are the same. The DGGE pattern showed that initial microflora counts are more is not the dominant spoilage bacteria,micro-organisnms can adapt to the environmentis are the dominna spoilage bacteria,chicken breast and drumstick of dominnat spoilage bacteria have some differences.The dominant spoilage bacteria of traditional culture and DGGE are not exactly the same,combination of two different approaches, determine the dominant spoilage bacteria of fresh chicken are Lactic acid bacteria, Enterbacter,Brochothrix thermosphacta, Shewanella putrefaciens,Granulicatella adiacens and Carnobacterium sp..2. This study was designed to identify the critical control point during broiler slaughter by exploring the microbial diversity in the produce of broiler slaughter using polymerase chain reaction·denaturing gradient gel elec-trophoresis(PCR-DGGE). In stage of broiler slaughter, the contamination microbia was sampled from broiler carcasses surface, the surface of workers’hand, the water in the pre-cooling pool, the air and broiler longissimus muscles of postmortem broiler carcasses, which was vacuum packaging at 4℃for 7 day. The results indicated that the processing of different treatment in the process of broiler slaughter will have different effects on microbial contamination of carcass surface, the type and number of microbia have increased after the broiler carcass to the visceral, however, the type and number of microbia have reduced after pre-cooling, microorganisms in the air increase in production, these operating points are also into areas of cross-contamination, in particular, the surface of workers’hand is the main reason causing cross-contamination.3. Several chemical substances were used to preservation of fresh chicken, the research including two aspects:1, Fresh chicken were dipped respectively in various chemical solution after division, reducing microflora counts determine to the best chemical solution.2,The essential of sodium phosphate, acetic acid, lactic acid and acidified sodium chlorite were screened as significant inhibition on dominant spoilage bacteria, and optimum combination the four chemical solution for inhibition dominant spoilage bacteria was evaluated by the three levels of four factors quadratic rotation design. The results showed that sodium hypochlorite, sodium phosphate, acetic acid, lactic acid and acidified sodium chlorite were screened have significant inhibition on dominant spoilage bacteria. Lactic acid were more positive than that of sodium phosphate, acetic acid,and acidified sodium chlorite, lactic acid, acetic acid, sodium phosphate and acidified sodium chlorite in the range of coded have the minimum values, dominant spoilage bacteria change with the rate of adding sodium phosphate is fastest,the results of regression analysis showed that the optimum proportion of combination of lactic acid, acetic acid, sodium phosphate and acidified sodium chlorite was 1.598%,1.805%,8.732%,0.07683%.

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