Ohmic heating systems made for commercial applications can vary greatly, but one example (Fig. 1.4) has 7 electrode columns, each comprised of polytetrafluoroethylene (PTFE) coverings and a single stainless steel cantilever electrode. These columns are structured vertically to allow for an upward flow of product, and are connected with insulated stainless steel tubes. Due to the increased electrical conductivity of products (see: Electrical Conductivity) as heat increases, the connecting tubes increase in length throughout the system to maintain the same electrical impedance. A temperature control system constantly monitors the temperature, flow rate, heat capacity and specific heat of a product to calculate the electrical power needed for the system. The processing capacities of such systems can range from 3 to 6 tons an hour. For validation of processing, a sterilized solution will be inoculated with a known organism, processed through the system at the known heat treatment for that organism, and then evaluated for survivor cell counts (Parrott 1992).