Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: December 2, 2004
Publication Date: December 1, 2005
Citation: Geveke, D.J. 2005. Nonthermal processing by radio frequency electric fields. In: Sun, Da-Wen, editor. Emerging Technologies for Food Processing. Amsterdam: Elsevier Academic Press. p. 307-322. Technical Abstract: Radio frequency electric fields (RFEF) processing is relatively new and has been shown to inactivate bacteria in apple juice at moderately low temperatures. Key equipment components of the process include a radio frequency power supply and a treatment chamber that is capable of applying high electric fields to liquid foods. The process is similar to the pulsed electric fields process, except that the power supply is continuous rather than pulsed; therefore, the capital costs may be less. Using an 80 kW RFEF pilot plant unit, Escherichia coli K12 in apple juice flowing at 1.0 l/min was exposed to an electric field strength of 20 kV/cm at a frequency of 21 kHz. RFEF processing reduced the population of E. coli by 2.7 log at 60 C and a hold time of 3 sec, whereas, conventional heating at the same conditions had no effect. The electrical cost of the RFEF processing was $0.0011/l of apple juice. Increasing the electric field strength, number of treatment steps, and temperature enhances the microbiological inactivation.