A Practical Verification of Ambient Temperature Slide Method (ATS Method) during Retort Sterilization

Abstract

In our previous report, we have proposed the Ambient Temperature Slide Method (ATS Method) as a rational way to estimate the central temperature of individually packed foods during retort sterilization. In this paper, we aimed to get new knowledge by specifically comparing ATS Method with simple One-Dimensional Finite-Difference Method (s-OFD Method) that was improved for the practical use of a conventional method using numerical calculation in order to solve the heat conduction equation (One-Dimensional Finite-Difference Method (OFD Method)). From the results of the experiments, it was clear that the Outside Film Heat-Transfer Coefficient h showed a smaller value than the expected one in the OFD Method and so surface heat transfer resistance is so large that it cannot be ignored. Because of this reason, it was thought to have been the obstacle for accurate estimating of the central temperature of foods. When we did parameter-fitting, ATS Method proved to be more than twice as good as the s-OFD Method in convergent accuracy and it was also good in convective foods as well as conductive foods. And, the F-value errors in simulation by using parameters obtained by parameter-fitting in the case of 4 food samples showed only one fifth of the value calculated on the s-OFD Method, it means that the convergent accuracy of ATS Method is five times better than the s-OFD Method. ATS Method showed approximately '1' in the ratio of thermal diffusivity for conductive foods. This result may indicate the possibility in simple theoretical calculation of parameter of heat transfer tau. From these results, ATS Method was thought to be several times better than the s-OFD method that is a conventional method and an improving one of OFD Method in estimating for the central temperature of foods.