Development of process equipment to separate nonthermal and thermal effects of RF energy on microorganisms

We developed a modified radio frequency (RF) dielectric heater, as a component of a continuous process, for isolating thermal and nonthermal effects of RF energy on microorganisms in liquid foods. The concept combines instantaneous input of RF energy to the food system with rapid removal of thermal energy. We used a double tube heat exchanger as an integral part of the RF heater. The outer tube was Teflon. The inner tube was stainless steel which was grounded in the RF circuit. Product flowed through the annular region between the two concentric tubes. Cooling water flowed through the grounded stainless steel tube. The RF energy was absorbed by the process fluid in the annular region. The cooling water flowing in the inner tube removed the thermal energy from the process fluid controlling the temperature.