Ohmic heating was applied to a Korean traditional fermented food containing red pepper paste, called Gochujang
with low thermal conductivity (0.458 W/m ∙ K), by varying frequencies (40–20,000 Hz) and applied voltages
(20–60 V). Contrary to conduction heating, the entire sample was heated uniformly, and the specific
heating rate was found to be highly dependent on the frequency, peaking at 5 kHz and 60 V. The results
showed that complex differential equation and the Runge–Kutta fourth-order method are suitable for
simulating the temperature profile during ohmic heating. The deactivation of vegetable cells of
Bacillus strains on fermented red pepper paste by ohmic heating was indicated by a 99.7% reduction, compared
with conduction heating for 8 min at 100 °C producing a 81.9% reduction. The organoleptic and physicochemical
qualities of the samples pasteurized by ohmic heating were nearly the same as those of raw samples, and higher
than those of conventionally heated samples.
Industrial relevance: The present study designed and implemented a novel sterilization process based on a static
ohmic heating system with low-frequency AC at the laboratory scale for fermented red pepper paste with a low
thermal conductivity (0.458 W/m∙K).
The developed system was used to investigate the mechanisms and characteristics underlying the induction of
ohmic heating and then, tested the pasteurization effect against microorganisms in fermented red pepper paste.
Comparing with conventional heating processes, ohmic heating could provide rapid and uniform heating,
thereby is more suitable for pasteurization and sterilization of viscous foods as fermented red pepper paste on
industrial thermal processing.