The commercial development of ohmic heating processes

The authors discuss the problems of heat transfer techniques in cook-chill food processing. These include destruction of flavours and nutrients, and particle damage arising from high shear often employed to improve heat transfer rates. These heat transfer problems have now been overcome with the development of ohmic heating technology. The ohmic heating effect occurs when an electric current is passed through an electrically conducting product. In practice, low frequency alternating current (50 or 60 Hz) from the public mains supply is used to eliminate the possibility of adverse electro-chemical reactions and minimise power supply complexity and cost. Electrical energy is transformed into thermal energy. The depth of penetration is virtually unlimited and the extent of heating is governed only by the spacial uniformity of electrical conductivity throughout the product and its residence time in the heater. The authors briefly discuss the design features, temperature control and market acceptance of ohmic heating