| Food poisoning incidents occur frequently in China and the main cause of the food poisoning is microorganisms in the future. Vibrio parahaemolyticus and Listeria monocytogenes are important hazards in seafood products. Microbiological risk assessment was regarded as an important approach to effectively control these hazards, and a technology scientific tool to evaluate the ability of the sterilization to reduce the risk. Therofore, this study aimed to(1) evaluate the current state and potential trend about food poisoning events of China in the future;(2) develop a novel non-thermal sterilization technology to eliminate the microorganisms on shelled fresh shrimp to ensure aquatic product safety;(3) evaluate the effect of the novel sterilization technology to reduce the potential infection risk of V. parahaemolyticus using quantitative microbial risk assessment, and provide strong technical support for public health. The main content of this study were summarized as follows: 1. Comprehensive analysis and evaluation of Chinese major food poisoning from 2001 to 2013.In order to further understand the characteristics of major food poisoning events in China from 2001 to 2013, Census X12 method of time series model, coefficient of variation(CV), t-value test and other analysis methods were used in this study. The results showed a decline in food poisoning cases year after year from 2006. Food poisoning was occurred mainly in the third quarter. Significance test showed that chemical factor was the most important factor, but the depth analysis showed that microbial factor should be the focus of prevention and control in future food safety. Compared with other places, the numbers dying of food poisoning at home accounted for the most. This study adequately reveals the current state and potential trend about food poisoning events of China in the future by multivariate statistical analysis methods. 2. Acidic electrolyzed water as a novel transmitting medium for high hydrostatic pressure reduction of bacterial loads on shelled fresh shrimp.Acidic electrolyzed water(AEW), a novel non-thermal sterilization technology, is widely used in the food industry. In this study, we firstly investigated the effect of AEW as a new pressure transmitting medium for high hydrostatic pressure(AEW-HHP) processing on microorganisms inactivation on shelled fresh shrimp. The optimal conditions of AEW-HHP for Vibrio parahaemolyticus inactivation on sterile shelled fresh shrimp were obtained using response surface methodology: NaCl concentration to electrolysis 1.5 g/L, treatment pressure 400 MPa, treatment time 10 min. Under the optimal conditions mentioned above, AEW dramatically enhanced the efficiency of HHP for inactivating V. parahaemolyticus and Listeria monocytogenes on artificially contaminated shelled fresh shrimp, and the log reductions were up to 6.08 and 5.71 Log CFU/g respectively, while the common HHP could only inactivate the two pathogens up to 4.74 and 4.31 Log CFU/g respectively. Meanwhile, scanning electron microscopy(SEM) showed the same phenomenon. For the naturally contaminated shelled fresh shrimp, AEW-HHP could also significantly reduce the micro flora when examined using plate count and PCR-DGGE. There were also no significant changes, histologically, in the muscle tissues of shrimps undergoing the AEW-HHP treatment. In summary, using AEW as a new transmitting medium for HHP processing is an innovative non thermal technology for improving the food safety of shrimp and other aquatic products. 3. Risk reduction assessment of the combined effect of acidic electrolyzed water and high hydrostatic pressure on Vibrio parahaemolyticus in aquatic product.Vibrio parahaemolyticus is widely found in different types of aquatic products, and has brought huge harm to food industry and public health. This study firstly combined acidic electrolyzed water(AEW) with high hydrostatic pressure(HHP) to inactivate the Vibrio parahaemolyticus in aquatic product, and the risk reduction of this technology was evaluated by quantitative microbial risk assessment(QMRA) model. The results showed that V. parahaemolyticus infection risk could be significantly reduced by this novel sterilization technology. Compared with untreated aquatic product, the final contamination levels of V. parahaemolyticus were decreased from 1.98 to-2.53 Log CFU/g, and the mean infection risks were reduced from 1.28 × 10-1 to 2.01 × 10-3 after treated by AEW combined with HHP. It led to a 98% reduction(from 1280 out of 10, 000 persons to 20 out of 10, 000 persons) in V. parahaemolyticus infection. Sensitivity analysis showed that all of treatment pressure, treatment time and NaCl concentration to electrolysis had negative correlation with infection risk of V. parahaemolyticus. In addition, this study also indicated that the novel sterilization technology combined with cold chain logistics process could serve the food industry to reduce the infection risk of V. parahaemolyticus extremely, and provide strong technical support for public health. |
PDF Full Text Request