Critical conditions accelerating the deterioration of fresh noodles: A study on temperature, pH, water content, and water activity

Abstract

In this study, critical temperature, pH value, water content, and water activity inducing the acceleration of fresh noodle deterioration were determined. Total plate count (TPC) and L* value were selected as the visualized parameters to characterize the deterioration of fresh noodles based on our previous study. Results showed that the critical temperature leading to the initial acceleration of fresh noodles was 20°C–25°C, critical water content was between 23% and 24%; the fastest darkening rate was detected at pH 8.0–8.5, while microorganisms kept a high growth rate during the whole range of initial pH 6–10. In addition, shelf-life model was built based on the deteriorating dynamics at room temperature, showing that microbial growth could be well fitted by both Gompertz and Logistic model, with higher fitting precision for Gompertz model and the fitting equation was y = 4.364 exp[−exp (1.032–0.086t)], R2 = .98855; Meanwhile, the darkening of fresh noodles could be fitted by quadratic polynomial model, with the fitting equation y = 76.0629 − 0.0165x + 5.98587x2, R2 = .9814. Practical applications This article presents the dynamics during the deterioration of fresh noodles and the critical conditions (moisture content and water activity, pH value, and storage temperature) accelerating the deterioration process. In addition, shelf-life model was built based on the deteriorating dynamics of fresh noodles at room temperature. Based on these results, a shelf-life stable fresh noodle product can be developed by applying different processing techniques and by keeping it in appropriate conditions, which will provide great guiding significance for the production and preservation of these products.