| China is one of the largest producers of broilers in the world,second only to the United States.In 2016,China's chicken production was 12.3 million tons,the second largest consumer of meat products,which is second only to pork.Live poultry trading and slaughter were the main traditional consumption patterns,however in recent years,the outbreak of avian influenza(H7N9 influenza in 2013)led to a sharp decline in consumer confidence in broiler consumption.At the same time,local governments issued the relevant mandatory provisions to ban live poultry slaughter and trading,and chilled fresh chicken has the advantages such as good hygiene condition and has been gradually accepted by consumers.As chicken meat provides a highly nutrient source of protein,unsaturated fatty acids,low fat and cholesterol content,and high water activity,meat deterioration can occur even in a short time under chilled conditions,affecting its nutritional value and flavor.Therefore,there is a need to provide effective preservation technologies to prolong the shelf life of chilled chicken meat and improve its quality by industries and researchers.In this paper,we mainly investigate the microbial contamination in the processing and storage of chilled chicken,to find out the potential pollution points in the process of chilled chicken and the dominant spoilage bacteria,to study the inhibitory effect of modified atmosphere packaging on dominant spoilage bacteria,and to determine the concentration range of modified atmosphere packaging,then effective inhibitory concentration range is applied to the chilled chicken,in order to provide a theoretical basis for the quality of chilled chicken production and storage process.The main contents are as follows:(1)Survey of bacterial contamination during processing and refrigerated storage of chilled chickenSamples of workshop air,contact surface,cutting tools,chilling waters and chicken carcass during the processing and refrigerated storage were taken and traditional microbial cultivation methods were employed to culture and count of bacteria so as to find the potential hazards in the processing technology of chilled chicken.Results showed that front production area(hanging room,bleeding room,scalding room and depilating room),the evisceration process,chilling water and various contact surfaces with chicken carcass were the potential sources of contamination.The separation between front area and back area(plucking room,eviscerating room,pre-chilling room,packaging room)exerted a critical effect on the reduction the microbial contamination of back area.Sanitation standard operation procedure should be carried out strictly on the stage of evisceration since it exacerbated the pollution of the chicken carcass.Subsequent rinsing and pre-chilling processes failed to reduce the bacteria,which led to the rising of initial microbial amounts of packed chilled chicken and shorten the shelf life.Therefore,the pre-cooling process should be optimized to further reduce the amounts of initial bacteria in chilled chicken.During the course of 6 days,the total number of colonies,Pseudomonas and Escherichia coli growth were showing a rising trend,at the end of storage,Pseudomonas bacteria number is close to the total number of colonies,indicating Pseudomonas is dominant spoilage bacteria of chilled chicken at the end of storage.(2)Inhibitory effects of different gas proportions on Pseudomonas fluorescens in chilled chickenThe chilled fresh chicken breast meat was used as raw material by inoculating Pseudomonas fluorescens which is about 103CFU/g after irradiation,stored under modified atmosphere packaging including M1 group(CO2/N2= 0%/100%),M2 group(CO2/N2 =20%/80%),M3 group(CO2/N2 =40%/60%)and M4 group(CO2/N2 =60%/40%),the air-packaging was used as control,changes in degree of depression,Pseudomonas,pH,TVB-N and putrescine during storage at(4±1)? were measured.Results showed the degree of depression increases with the storage time,and increases with the increase of the concentration of carbon dioxide,but the pH,Pseudomonas fluorescens count,the volatile base nitrogen and the peroxamine content increased with the storage time,and decreased with the increase of the concentration of carbon dioxide,M4 group showed the best preservation effect,but the M4 group of modified air box depression significantly higher than the others,affecting the appearance of the product.No difference was found in degree of depression?Pseudomonas fluorescens count?pH?TVB-N and putrescine of M3 and M2,which achieved the same effect of preservation.Generally,the percent of 20%-40%carbon dioxide can slow down the quality deterioration of chilled chicken and prolong the shelf-life.(3)Application of modified atmosphere packaging technology in chilled chickenFresh chicken meat were stored in air and under modified atmosphere packaging(CO2/N2=20%/80%?CO2/N2=30%/70%?CO2/N2=40%/60%)at(4±1)?.The results showed that no difference was found in degree of depression?Pseudomonas fluorescens count?Pseudomonas?pH?TVB-N and putrescine,which can achieve the same effect of preservation.Generally,under the condition of(4+1)? storage,CO2/N2=20%/80%modified atmosphere packaging can slow down the quality deterioration of chilled chicken and prolong the shelf life.Under the condition of(4±1)? storage chilled chicken in CO2/N2 = 20%/80%(v/v)and pallet packaging mode shelf life are:9 and 3days. |
PDF Full Text Request