| Fresh cooked noodles are a new type of convenience food but easily perishable for their high moisture. Especially in summer, the phenomenon such as producing acid, growing germs easily appears, which exists a large potential hazard of food safety. The shelf-life prediction model of food is an effective method to evaluate food quality and control food safety. It can assess food quality quickly, predict the remaining shelf-life of food and provide support for early warning of food quality and safety. At present, domestic and overseas scholars have screened the operational prediction index of perishable food through considerable research. And the shelf-life prediction models of perishable food, such as, chilled pork, cooked ham, cooked rice, have been established. However, the shelf-life prediction index and model of fresh cooked noodles have seldom been studied.Therefore, fresh cooked noodles made by specific process were used in the study. The effect of microwave treatment and storage temperature on the quality of fresh cooked noodles was studied. The applicable shelf-life prediction index and its threshold were determined by analyzing the change of quality index. The three-phase linear model, modified Gompertz model and Logistic model were adopted to fit the growth curve of the microbe in fresh cooked noodles stored at 0℃,4℃,10℃,15℃, 20℃,25℃, respectively. Then the optimal model was determined and the shelf-life prediction model was established by the optimal model combining with the square root models. In order to define the bacterium compositions and advantage group which caused spoilage, the growth changes of microorganisms in fresh noodles stored at different temperatures were analyzed. The main conclusions were as follows:(1) The shelf-life of fresh cooked noodles could be effectively extended when the microwave treatment continued to 30s or above, and 45s treatment was best for the quality of fresh cooked noodles.(2) The quality indexes were significantly changed during storage. The higher the storage temperature was, the faster the change would be. The sensory quality, pH, springiness, and cohesiveness of fresh cooked noodles gradually decreased, the microorganisms increased, and the hardness increased firstly then decreased with the time.(3) The pH and TPC (total plate count) were the effective indexes to determine the shelf-life of fresh cooked noodles. And at the end of shelf-life, the threshold of the value of pH and TPC were 6.24 and 105.87 CFU/g, respectively.(4) The microorganism growth curve of fresh cooked noodles was fitted by the three-phase liner model, the Logistic model and the modified Gompertz model, respectively. The results showed that the Logistic model was slightly better than three-phase model and the modified Gompertz model for that the value of RMSE obtained from the Logistic model was lower and the value of R2 was higher than the other models.(5) The shelf-life prediction model of fresh cooked noodles was established by the Logistic model combined with the square root models, and the formula was model was validated by fresh cooked noodles stored in 8℃,13℃ and 16℃, and the results showed that the average relative error was 8.67% between the observed shelf-life and the predicted shelf-life, which indicated that the established model could effectively predict the shelf-life of fresh cooked noodles stored at 0～25℃.(6) Bacillus, Clostridium and Paenibacillus were the major components to result in corruption of fresh cooked noodles. The dominant bacteria were Bacillus and Paenibacillus at 10℃. Bacillus and Clostridium were in advantage position under the temperature of 20℃. Whereas, the predominating population only were Bacillus at 15℃,25℃ and 37℃, respectively. |
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