Develop Predict Model Of Microbes On Cold Fresh Pork And Method For Antimicrobial Be Researched

Both internal and external microflora of cold fresh pork were analyzed and identified by selective mediums, and their changes during the whole storage period were also studied. Brochothrix thermosphact, Pseudomonas, lactic acid bacteria, two strains of Enterobacteriaceae and a Staphylococcus.sp were identified; B. thermosphact was the dominating bacteria for spoilage of pallet packaged cold pork. During the whole storage, Pseudomonas and Enterobacteriaceae had evident growth, and the microbes inside the pork grew faster than those outside of it.The counts of Brochothrix thermosphacta on chilled pork under various storage temperatures (0℃,4℃,7℃,10℃,15℃) were monitored. Growth models of Brochothrix thermosphacta at different temperatures were developed using SAS9.1 software, and the growth of Brochothrix themosphacta at 0-15℃could be well indicated by a Gompertz type model. The model of relationships between temperature and maximum specific growth rate, and between temperature and lag phase were built respectively using Belehradek model with R-square more than 0.99. The results showed that it could finely describe the influence of temperature on maximum specific growth rate and lag phase. The prediction model of shelf-life of chilled pork storing at 0℃to 15℃were developed. The real and predicted shelf-life of chilling pork was compared at 3℃, and the basic errors was 1.6%,which indicated the model could effectively predict the microbial quality and remaining shelf-life of chilling pork stored at 0℃to 15℃.The inhibitory effect of processed tannic acid on Pseudomonas,B.thermosphact, Staphylococcus and Enterobacteriaceae were experimented by the disc diffusion test. It showed that processed tannic acid can inhibit gram-positive organisms obviously (B.thermosphact and Staphylococcus) with an inhibitory zone of 22 mm under the concentration of processed tannic acid 2.5%. About gram-negative bacteria (Pseudomonas and Enterobacteriaceae.coli) could not be well inhibited. Studies about antimicrobial activity on cold fresh pork which treated with processed tannic acid, lactic acid and 75% (v/v) alcohol, and sterile water as control group showed that processed tannic acid could more effectively restrain bacteria on cold fresh pork than that of same concentration of lactic acid.The impacts of different concentrations of processed tannic acid on microbes of cold fresh pork were studied. The Gompertz model was employed to describe growth parameters such as specific growth rate and lag time to indicate antimicrobial activity of different concentrations processed tannic acid under 4℃. The result showed that as the concentration of processed tannic acid increased, the antimicrobial activity was better. When the concentration of processed tannic acid was 2.5%, the lag time increased to 7 days. The deviation and accurate factors of model were 1.35 and 1.00 respectively, which demonstrated the model could effectively predict the microbial growth on cold fresh pork treated with different concentrations of processed tannic acid.