Experimental and Analytical Temperature Distributions during Oven-Based Convection Heating

ABSTRACT:  Mathematical models, combined with experimental evaluation, provide an approach to understand, design, and optimize food process operations. Magnetic resonance imaging (MRI), as an experimental technique, is used extensively in both medical and engineering applications to measure and quantify transport processes. Magnetic resonance (MR) was used in this study to assess a mathematical model based on Fourier's second law. The objective was to compare analytical solutions for the prediction of internal temperature distributions in foods during oven-based convective heating to experimental temperature measurements and determine at what point during the heating process a coupled heat and mass transport process should be considered. Cylindrical samples of a model food gel, Russet potato and rehydrated mashed potato were heated in a convection oven for specified times. Experimentally measured internal temperatures were compared to the internal temperatures predicted by the analytical model. Temperatures distributions in the axial direction compared favorably for the gel and acceptably for the Russet and mashed potato samples. The MR-acquired temperatures in the radial direction for the gel resulted in a shallower gradient than predicted but followed the expected trend. For the potato samples, the MR-acquired temperatures in the radial direction were not qualitatively similar to the analytical predictions due to moisture loss during heating. If temperature resolution is required in the radial direction, moisture losses merit the use of transport models that couple heat and mass transfer.