2018 Volume 19 Issue 2 Pages 57-78
The author has conducted engineering research on thermal food processing (TFP) using various heating methods to intend optimal operations. In this paper the following four themes related to TFP were reviewed. (1) Heat and moisture transfer and shrinkage deformation: Theoretical analysis of heat and moisture transfer, which are the most basic phenomena in TFP, was reviewed, and the strain-stress analysis was introduced to reveal the mechanism of shrinkage deformation and crack formation of foods during drying or roasting processes. (2) Heat transfer with convection: When convection occurs in a container or a vessel, the heat transfer rate becomes much larger than that of heat-conductive food, and it is necessary to consider the natural convection in the fundamental equations. A method to predict the temperature history of liquid food using its apparent viscosity was developed. In addition, an analysis of natural convection in a pan heated by induction heating (IH) and gas range using Computational Fluid Dynamics was outlined. (3) TFP with internal heat generation: During microwave heating, radio-frequency heating, and ohmic heating, foods can be heated faster than conventional heating methods because of the internal heating, but uneven heating is a crucial problem. A computational method was introduced for predicting the temperature distributions in food by coupling an analysis of the electromagnetic field and the heat transfer. (4) Chemical reaction accompanying heating: Various chemical reactions occur with heating, which affects the quality of foods. Kinetic analysis of protein denaturation and color change due to Maillard reaction during fish grilling was outlined.
