Study On Shelf-Life Prediction And Preservation Techniques Of Roast Sausages

Roast Sausage which is a western low temperature-heated meat product is popular by theconsumer deely and has a large share of the market. For protecting nutrients and sensoryquality, its processing temperature is lower than usual so that microbes are not killedcompletely, and then shelf-life of roast sausage is shorter than usual. So studying on shelf-lifeprediction and preservation techniques of roast sausages is very important for prolonging theshelf-life. In this thesis, the microflora of corrupt roast sausages was analysed and spoilagebacteria of roast sausages was isolated and identified; Growth kinetics model of spoilagebacteria in roast sausages and shelf-life prediction model were established; Bacteriostaticeffect of composite bacterioastats on roast sausage spoilage bacteria was studied throughresponse surface methodology; The heat resistance of spoilage bacteria was also studied.Theabove study laid a theory foundation for production and distribution of roast sausage in future.The results indicated:1. The microflora of corrupt roast sausages was analysed by selective medium and spoilagebacteria of roast sausages was isolated and identified. The results show that the spoilagebacteria of the roast sausages included Bacillus, Pseudomonas and lactic acid bacteria. AndEnterobacteriaceae, Staphylococcus, yeast and molds were not detected.2. Growth kinetics model of spoilage bacteria and shelf-life prediction model were establishedthrough termly determining the data of the same batch samples which were stored at4℃、10℃and25℃, respectively. The results show that Growth kinetics models using the modifiedGompertz model which described well the growth of spoilage bacteria under4-25℃areestablished, and the relationship between temperature and kinetic parameters μmax, λ phase aremodeled and well described by Belehradek (square root). R2of these models are all above0.940, and except for primary model of Pseudomonas at25℃，Bf, Afof primary model andresidual error of secondary model are within the acceptable level. The predicted model ofshelf life under4-25℃is constructed by primary model and secondary model.3. Bacteriostatic effect of composite bacterioastats on roast sausages spoilage bacteria wasstudied through response surface methodology. Minimum inhibitory concentration of threeeffective bacteriostats which were selected from six bacteriostats by plate dilution methodwere determined by liquid double dilution method. Three effective bacteriostats were compounded by response surface methodology. The results show that clove oil, ε-Polylysine,nisin are more effective than other bacteriostats and minimum inhibitory concentration ofthem are0.125%,0.00625%,0.025%, respectively. Multivariate regression model are builtthrough response surface analysis and optimal proportion of composite bacteriostats is cloveoil0.849%+ε-Polylysine0.050%+nisin0.050%.4. The heat resistance of spoilage bacteria was also studied in this thesis. The results show thatsurvival curve and thermal death time curve of spoilage bacteria which could describedregulation of spoilage bacteria survival and death at different temperatures were drawn and R2of them were all above0.800. D value of M1at90、93、95、100℃were37.037,31.243,24.010,5.071min, M2at60,65,70,75℃were4.286,13.889,9.901,7.519min, M3at60,65,70,75℃were4.286,13.889,9.901,7.519min. Z value of M1, M2, M3were10.385,26.509,33.142℃,respectively.