Non Thermal Preservation of Food – Ohmic Heating
Food can be heated by either direct or indirect methods.
Direct heating: In this method of heating, heat is generated within the product. Example; Dielectric heating, Ohmic heating, Pulse Electric Field (PEF), High Pressure Technology (HPT).
Indirect heating: This method of heating relies on heat that is generated externally being applied to the surface of food mostly by radiation, convection and conduction. Example; Infrared heating.
Non thermal preservation of food includes food preservation by following methods.
1. Ohmic heating
2. Dielectric heating
3. Pulse electric field (PEF)
4. High pressure treatment (HPT)
5. Oscillating magnetic field (OMF)
Ohmic heating:
operates by direct passage of electric current through food product with heat generated as a result of electric resistance. In conventional heating, heat travels from heated surface to product by conduction and convection paths. Ohmic heating is also called “resistance heating” or “electro heating”. Here alternating electric current is passed through a food and electrical resistance of the food causes the power to be translated directly into heat. As the food is an electrical component of heater, it is essential that its electrical properties (resistance) are matched to the capacity of heater. Read more