Ohmic heating for food processing

Abstract

[Excerpt] Introduction: Ohmic heating (OH) (also called Joule heating, electrical resistance heating, direct electrical resistance heating, electroheating, or electroconductive heating) is defined as a process where electric currents are passed through foods to heat them (Figure 18.1). Heat is internally generated due to electrical resistance [1]. OH is distinguished from other electrical heating methods by (a) the presence of electrodes contacting the foods (in microwave and inductive heating electrodes are absent), (b) the frequency applied (unrestricted, except for the specially assigned radio or microwave frequency range), and (c) waveform (also unrestricted, although typically sinusoidal). OH concept is well known, and various attempts have been made to use it in food processing. A successful application of electricity in food processing was developed in the nineteenth century to pasteurize milk [2]. This pasteurization method was called “electropure process” and by 1938, it was used in ∼50 milk pasteurizers in five U.S. states and served about 50,000 consumers [3]. This application was abandoned apparently due to high processing costs [1]. Also, other applications were abandoned because of the short supply of inert materials needed for the electrodes, although electroconductive thawing was an exception [4]. [...]