Study On The Preservation Technology Of Pre-processed Fresh Chicken

The pre-processed fresh chicken is a new kind of processed meat product. It is greatly popularbecause of its convenience, rich nutrition, supple texture and so on, and its product species is increasing, and its production and consumption is also increasing day by day. The shelf life of the pre-processed fresh chicken is short owing to without sterilization totally, so its development is restricted.In addition, the research for preservation of pre-processed fresh chicken has not been reported. Thus, to study the preservation of pre-processed fresh chicken and extend its shelf life are of great significance. This paper mainly studied the effect of preservative, packaging methods, supercritical CO₂ sterilization on the shelf-life of pre-processed fresh chicken, as so to supply meat manufacture with theory and technology on extending the shelf life of pre-processed fresh chicken.1.To select the natural preservatives which have better fresh-keeping effect to pre-processed fresh chicken by the single factorial experiment, then the quadratic orthogonal rotational combining design experiment was adopted to combine preservatives for the purpose of developing a combined-preservative to suit pre-processed fresh chicken preservation. The results showed that six natural preservatives of five different concentrations possess certain fresh-keeping effect.The fresh-keeping effect of sodium lactate, nisin and lysozyme are better, polylysine and tea-polyphenol are secondary, natamycin is worst.When sodium lactate, nisin and lysozyme are combined, the order of fresh-keeping effect is sodium lactate>Nisin>lysozyme.There is significant synergy between sodium lactate and nisin (P<0.05), there is synergy between nisin and lysozyme, between lysozyme and sodium lactate too, but the synergy is not significant (P>0.05).The optimum percentage of combined-preservative is 0.016% Nisin, 0.022% lysozyme, 3.30% sodium lactate, and it can make the shelf life of pre-processed fresh chicken extend to 18 days.2.To select the spice essential oils that have better fresh-keeping effect to pre-processed fresh chicken by the single factorial experiment, then the orthogonal experiment was adopted to combine preservatives for the purpose of developing a combined-preservative to suit pre-processed fresh chicken preservation. The results showed that six spice essential oils of five different concentrations possess certain fresh-keeping effect. The order of fresh-keeping effect is cinnamon essential oil> mustard essential oil>garlic essential oil>clove essential oils>citrus essential oil>star anise essential oil, and the fresh-keeping effect of cinnamon essential oil,mustard essential oil, clove essential oils, citrus essential oil increases with concentration increases.When clove essential oils, cinnamon essential oil and mustard essential oil are combined, the effect of mustard essential oil on the pre-processed fresh chicken fresh-keeping is most significant, cinnamon essential oil is secondary, clove essential oils is not significant. The shelf life of pre-processed fresh chicken could be extended to 21 days when the pre-processed chicken was treated by the combined-preservatives of 0.03% clove essential oils, 0.09% cinnamon essential oil and 0.06% mustard essential oil, packaged in tray by plastic film and stored at (4±1)℃. 3.In order to extend the shelf life of pre-processed fresh chicken,the fresh-keeping effect of tray packaging, customary packaging,vacuum packaging, high-oxygen packaging (50% O₂ +25% CO₂ +25% N₂), low-oxygen packaging (25% O₂ +25% CO₂ +50% N₂), anaerobic packaging ( 25% CO₂ +75% N₂) on low-temperature stored pre-processed fresh chicken were studied. The total bacteria count, the pH value, the color, the TBA value and the TVB-N value for meat samples were tested and analyzed during storage.The results showed that order of fresh-keeping effect was as follows: anaerobic packaging> vacuum packaging> low-oxygen packaging> high-oxygen packaging> customary packaging> tray packaging.The pre-processed fresh chicken were packaged in anaerobic and stored 0-4℃,and its shelf life could be extended to 10 days.4.The inactivation effects of different pressure, temperature and time supercritical CO₂ on bacterium in the pre-processed fresh chicken were investigated ,and the Weibull model,Modified Gompertz model,Logistic model were selected to fit the inactivation kinetics of supercritical CO₂. Accuracy factor (Af), Bias factor (Bf),Sum of Square Root(SS),Root Mean Square Error (RMSE)and coefficient of determination (R²) were chosen as the estimated indices for the goodness of the fitting.The results showed that the inactivation effects of supercritical CO₂ gradually increase along with the increase of the pressure, the temperature and the time.The fitting degree of Logistic model is best, the Modified Gompertz model is better, the Weibull model is worst.