Design and development of continuous type ohmic heating unit

Abstract

Researches on application of ohmic heating for processing of liquid food have been limited to batch type operations. This limits its applicability for various foods with reduced processing capacity. Ohmic heating can have wider application in food processing when used in continuous mode. A continuous type ohmic heating unit was designed for volumetric/processing capacity of 10 litres/hour and which can be able to elevate the temperature up to 20 ± 2.5 0C. Concentric tubes (2 Nos) with inner tube diameter 5 cm; outer pipe 7.5 cm and length 1.25 m was selected based on preliminary trials (Joule’s law and Ohms law) for considering various piping combinations get the desired capacity and elevated temperature. The selected pipe sizing provided a 1.25 cm gap between the pipes for the liquid flow. The designed and fabricated ohmic heating section was tested for its performance at continuous mode at potential difference 60 V. As the solute content was increased, higher temperature elevation was observed in the liquid food.