The Research On The Quality Control Of Pre-processed Fresh Mutton And Safety Forecast

Pre-processed fresh mutton is a kind of convenient food processed by press, water retaining agents, flavoring, ultra-high pressure and packaged with vacuum,then stored under4℃atmosphere. But there are some problems, such as juice loss, rapid growth of microorganisms, short shelf life. Therefore, security issues become the most important problems for consumers. This research applies hurdle technology and predictive model to deal with theses problems. The aim is to provide a theoretical basis and technical support. The contents and results are as follows.1Response surface methodology for the effects of ultra-high pressure processing and water retaining agents on the dehydration rate of fresh mutton. Sodium pyrophosphate (SPP), sodium tyipolyphosphate (STP) and soybean protein isolate (SPI) was chosed as water retaining agents. Based on single factor experiments, dehydration rate was measured. Response surface methodology (RSM) was applied and sensory quality was considered to obtain the optimal combination. It was0.20%SPP,0.25%STP,5.00%SPI,200.00MPa ultra-high pressure,0.57%dehydration rate.2Hurdle technology was applied to extending product’s shelf life. Hurdle factors included reducing amount of bacterium and Eh level, adding preservative, ultra-high pressure and low temperature. The research found that0.20%lactic acid,0.10%acetic acid,0.15%citric acid could reduce pH level and amount of bacterium. Under this combination, mutton’s pH was5.99and the amount of bacterium was3.28(lgcfu/g), which was the lowest for the treatment groups. Moreover, amount of bacterium reduced by12.29%processed by16%NaCl solution.3The changes of mutton quality under4℃and the determination of the specific spoilage microorganisms.The research determined the changes of mutton quality within the shelf life, including total number of colonies, level of TVBN, sensory quality score. The result was that mutton were inedible on30th day. At this point, we analyzed the characteristic of flora on mutton considering atmosphere changes and bacteria growth characteristics. The conclusion were that Enterobacteriaceae was the specific spoilage microorganisms for the pre-processed fresh mutton and the Ns was5.83.4Establishment of growth predictive models for Enterobacteriaceae and shelf life prediction.The mutton was infected with Enterobacteriaceae, and was vacuum packaged at4℃,10℃,15℃,20℃for storage, measured the growth of Enterobacteriaceae respectively and analyzed with CurveExpert software to construct growth kinetics models. The results showed that growth of Enterobacteriaceae could be well described by Gompertz model in the range of temperature4to20℃. The correlation regression of Belehradek model finely described the influence of temperature on growth. The validation was carried out by comparing actual with predicted growth of Enterobacteriaceae at8℃and16℃, respectively. Bias and accuracy factors were1.0116、0.9623and1.0673、1.0715respectively. Finally, we established The shelf life predictive model for mutton under4℃-20℃.Relative error for actual and predicted shelf-life were6.62%、1.36%respectively. It was suggested the built model was effective.