Food preservation by " OHMIC HEATING" as best alternative to conventional heating technique

Ohmic heating results in faster heating of food along with maintenance of color and nutritional value of foods, efficient alternative to the conventional heating method of enzyme inactivation, causes electroporation of cell membrane and reduces energy requirement during processing by pre gelatinization.

Ohmic heating or Joule heating is an advance terminal processing method where in the food material serves as an electric resister, is heated by passing electricity through which result in rapid and uniform heating. A voltage difference between the ends of a conductor creates an electric field that accelerates charge carriers in the direction of the electric field, giving them kinetic energy. Thus, energy from the electrical field is converted into thermal energy. The main difference between ohmic heating and other electrical heating methods (such as dielectric heating, microwave) is that electrical energy is directly dissipated into the product. The electric field strength, residence time, and the electric conductivity of a food product are the major critical process factors, which strongly influence temperature generation and ohmic heating efficacy.

Applications existing for Ohmic heating in food processing include Blanching, Thawing, Peeling, Evaporation, Dehydration, and Extraction. The advantages of ohmic heating include better product quality, less cooking time, lower capital cost, better energy efficiency as about 90 % conversion of electricity into heat and also an environment friendly process. In spite of advantages its higher initial cost, lack of its applications in foods containing fats and oils, and less awareness limit its use. At the end we conclude that more research is required to minimize its consequences for its commercial application.