ELECTRICAL CHARACTERISTICS INVESTIGATION OF OHMIC HEATING ON PARTICULATE FOOD STERILIZATION

Abstract

: Ohmic heating is a method where alternating current is passed through a particulate food medium acting as a resistance between a pair of positive and negative electrodes which in turn volumetrically heats up the entire mass of the food systems. In order to effectively control ohmic heating for particular foods sterilization, the full understanding of electrical characteristics of ohmic heating needs to be investigated and determined using samples of popular food in Sarawak. Thus a joint study between electrical and food technology teams was formed at the Electrical Engineering Laboratory in UCTS to design the electrical circuit model and verify the main electrical characteristics of an ohmic heating process on particulate foods. The ohmic heating electrical system model was first set-up to prove that the model is working. The model is a simple electrical system that needs only a variable transformer to supply alternating current to the electrode of the ohmic cell and the particulate food sample. Electrical tests and measurements on two local popular fruits known as Sarawak pineapple and Dabai were conducted. The experiments have observed that the current and temperature rise significantly with time for different concentrations of the food postulate. These experiments also verified that ohmic heating process produces a uniform heat distribution within the food medium and the associated electrical characteristics like electrical conductivity (σ) were determined. The heating process is observed to be more efficient compared to other known heating process methods. The Food Technology department then have designed and fabricated Ohmic Heating (OH) test equipment prototype with the purpose of rapid repetition of the experimental procedure and exploring ohmic heating for other industrial applications.