Temperatures and microbial growth in meat blocks undergoing air thawing

Abstract

Two techniques were used for evaluating the hygienic quality of the process of thawing cartoned meat, a temperature function integration (TFI) technique and a finite difference technique. The TFI technique yielded microbial growth values whth were usually within one generation of measured values. The exception was in the lower corners of cartons, where anaerobic conditions caused by the accumulation of drip led to directly determined values being much lower than those obtained in the top corners. To ensure the success of the TFI technique, it is essential to measure the temperature where the warming of the product is quickest. The finite difference numerical model of the process was not built entirely from first principles but involved some degree of curve-fitting against experimental data. Numerical modelling provides a flexible design tool which allows quick evaluation and optimization of thawing and other thermal processes. Numerical modelling is better at predicting ‘worst case’ microbial growth than TFI, as it does not suffer from the uncertainty of physically locating the warmest spot.