| Sauced meat products have gradually become the mainstream consumption of the traditional cooked meat because of its delicious taste, convenience and other characteristics. However, as sauced meat products are vulnerable to contamination and corruption during cold storage, and lead to food safety problems. Therefore, it is very important to research on its dominant spoilage bacterias, and analyzed their impact on the shelf life of the sauced meat product, and ultimately establish an effective shelf life prediction model.In this paper, the initial bacteria composition of the sauced meat from current market, the major shopping malls as well as some well-known brand, supermarkets and night market in A, B and C districts of Shanghai were determined. The dominant spoilage bacterias of the sauced meat which from different brands and areas were isolated and identificated by the physiological and biochemical tests. Meanwhile, the total plate count (TPC), pH value, TVB-N (Total Volatile Basic Nitrogen) value, color value and the rate of water loss of sauced beef were determined during the storage time at 4?. The correlation of TPC and other physiochemical indexes was analyzed. The main factor which affects the quality of beef sauce was determined. Modified Gompertz model of TPC was set up and predictive model of shelf life was constructed at the basis of TPC. The results showed that:(1) The E. coli, Bacillus, Lactobacillus, Micrococcus and Staphylococcus were found common in the traditional sauced meat products during cold storage. The E. coli was the dominant bacteria and followed by the Bacillus. There was a big difference between different brands of microbial contamination and no difference between different supermarkets in terms of microbial contamination.(2) The TPC and E. coli count kept increasing and the count of E. coli was more than the TPC during cold storage. The dominant spoilage bacterias was determined and the final count of E. coli was around 107CFU/g.(3) The analysis of quality changes of sauced beef during cold storage was showed that the pH value at first declined and then rose, the TVB-N kept increasing while the rate of water loss decreasing, the redness a value and DE value of sauced beef were found to gradually decline with the preservation time, which were consistent with the color of sauced beef continues to darken.(4) According to the Pearson analysis when P<0.05, the count of E. coli, redness a value and TVB-N value were showed the best correlation with TPC, the pH value was significantly correlated with TPC, especially the pearson indexes of TPC and TVB-N was maximum, the correlated between TPC and quality indexes were higher than other physiochemical count.(5) The sensory evaluation system was established, and spoilage limit of TPC was 5.05 log(CFU/g) when TVB-N reached 20mg/100g. The Modified Gompertz model was set up at 4? and R2 was 0.95. Mathematical model developed from the TPC was as follows: N(t)=2.06+(6.89-2.06)×{Exp[-Exp[(0.02×2.72/(6.89-2.06))×(75-t)+1]]}, the model was validated at 4?, the results showed that the Bf value was ranged between 0.9 to 1.15 and the Af value was near 1. The predictive model of shelf life was constructed at the basis of TPC as follows:SL=?-[(6.89-N0)/?max×2.72]×{ln[-ln[(5.05-N0)/(6.89-N0)]-1]}. |
PDF Full Text Request