ABSTRACT
Ohmic heating occurs when an alternating current is passed through a food that is electrically conductive, therefore heat generation takes place volumetrically, and the electrical energy is directly converted into heat causing a temperature rise. This system is comparable to an electrical circuit, which is comprised of a resistance and a source of current at an appropriate voltage gradient. The food product placed between the two electrodes acts as the resistance when an alternating current passes through it. In other words, the food is made part of an electrical circuit. Other synonyms used in the literature to describe this principle of heating are: direct resistance heating, Joule effect heating, electro-conductive heating and electro-resistive heating. Classical heat-transfer mechanisms such as convection or conduction are minimal. It offers an alternate way to rapidly heat food, bypassing conventional heating systems. Other direct volumetric heating techniques are also available as classified into three categories by Pain et al. (1995): steam (e.g., injection and infusion), radiation (e.g., infrared, microwave, and radio frequency) and the Joule effect in which Ohmic heating is found. Ohmic heating is comparable to microwave heating without an intermediary step of converting electricity into microwaves through the magnetron before applying to the product. Varghese et al. (2012) reviewed the Ohmic heating technology and its application in food processing and concluded that this technique is especially advantageous in processing semi-solid, particulate foods. It has proven advantages over conventional thermal processing and novel thermal alternative
3.1 Introduction ............................................................................................................................ 17 3.2 Importance of EC ................................................................................................................... 18
3.2.1 Liquid Food Conductivity ...........................................................................................20 3.2.2 Solid Food Conductivity ............................................................................................. 21 3.2.3 Conductivity of Multicomponent Food Matrix ..........................................................22
