Corona discharge development and its application to eliminate microorganism in raw milk

Abstract

Raw cow's milk or fresh milk is a natural food with a complete nutrients which provide many benefits for human health. Raw milk also provides almost ideal media for various microorganisms to grow rapidly that can harm human digestion, or make damages the milk itself. In attempt to investigate an appropriate processing technology as an alternative of thermal pasteurization, we developed non thermal corona discharge to eliminate total number of various microorganisms in milk. The generated corona discharge used 7 pins to plate surface configuration. With a distance 15 mm between the electrodes, the applied voltage of 6.48 kV by a homemade high voltage AC power supply yields in corona discharge that has temperature lower than 30°C after 8 minutes operation. The time dependent effects of the implementation of this discharge to raw milk were carried out at time interval 2, 4 and 8 minutes. It was found that there was three different types of bacteria colony morphology in the microorganism population of raw milk. The microorganism counts were decrease for 2 and 4 min corona treatments. However, when the corona treatment was done in 8 min, the total number of microorganism increased significantly. Although the corona discharge shows the potential benefits in milk decontamination processing at low temperature, more detailed study should be carried out to confirm the suitable in real application including the nutrient composition before and after treatment.