Critical review of radio-frequency (RF) heating applications in food processing

Conventional thermal treatment in food processing relies on the transfer of heat by conduction and convection. One alternative to this conventional thermal treatment is radio-frequency (RF) heating in which electromagnetic energy is transferred directly to the heated product. The longer wavelengths of RF compared with microwaves are able to penetrate further into the food products resulting in more even heating. A review of RF heating for the food processing industry is presented here with an emphasis on scientific principles and the advantages and applications of RF. Applications of RF heating include blanching, thawing, drying, and processing of foods. RF heating represents considerable potential for additional research and the transfer of technology to the food processing industry. Computer simulation can be used to improve RF heating uniformity. Moreover, the heating uniformity in the rotated eggs is greater than in the static eggs. RF has also been used to blanch vegetables to increase ascorbic acid content to achieve the highest vitamin C levels. The use of the thawing technology has resulted in better quality of treated food. There has been increased interest in the RF-drying method due to the homogeneity of heating, greater penetration depth, and more stable control of the product temperature. RF-treated meat had improved quality and coagulation with acceptable taste and appearance. In addition, RF heating is used in pasteurization of yogurt and destruction of microorganisms in liquid and solid foods.