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Development of a selective heating technique for food components using Infrared radiation |
S. JUN and J. M. K. Irudayaraj. Dept. of Agricultural & Biological Engineering, Pennsylvania State Univ., 107 Agricultural Engineering Bldg., University Park, PA 16802 In the food-processing field, selective heating has never been applied despite its potential mainly because of technical limitations of realizing the optical properties of food materials on the thermal processor. In this study, spectral manipulation on radiative heating of food components was accomplished using a novel infrared heating system. The incident IR radiation could be controlled to have a variety of spectral distributions corresponding to the optical filter chosen. Controlled radiation can stimulate specific optical response of the targeted object, based upon the coincidence between the IR spectral distribution and the IR absorptivity of food. Soybean protein and starch powder were selected to verify the differential IR heating method. Both the surface and center temperature profiles of two samples measured during 5 min heating were compared with respect to various filter selections. At the surface, selective heating technique could manipulate the magnitude of the thermal variations between two food components, dependent upon the IR spectral distributions, which could not be accomplished with other heating methods. The temperature at the center of each sample showed little significant discrepancy because of the nearly exhausted infrared energy. Mathematical models, based on the heat flux ratios of soy protein to starch and the IR spectral conditions, supported the thermal variations measured. Selective heating technique can thus be applied to food thermal processing to pursue selectivity or uniformity heating effect on the final product, such as food coating. This technique is also promising in terms of the disinfection of microorganisms in foods because it could deliver the lethal energy only to microorganisms without damaging the food components.
Session 13, Food Engineering: Thermal processes
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