Bacterial inactivation by using non thermal argon plasma jet and its application study for non thermal raw milk processing

Abstract

The present paper deals with the research about bacterial decontamination by using non thermal argon plasma jet and exploring the argon plasma jet application study for non thermal raw milk processing. Escherichia coli and Staphylococcus aureus bacterias were chosen in this research to be treated by argon plasma jet system, due to those types of bacterias are usually contained in raw milk. The bacteria that have been cultured in agar media was irradiated by argon plasma jet at various plasma treatment time to understand the effect of the jet on the bacteria growth. It was found that the growth of bacteria was inhibited proportionally with the plasma treatment time in their appropriate agar media. This was clarified by the increasing of inhibition zone diameter of bacteria’s growth in petri dish. From this result, attempting the application of the developed plasma system for raw milk processing by adopting the system to generate plasma under liquid milk. Argon plasma discharge inside the milk solution can be generated by applying 1.5 kVp-p electrical AC power and the operation temperature could be constantly kept under 32°C even after 15 min underwater plasma treatment to confirm non thermal processing. Investigating the effect of plasma treatment time on non thermal raw milk processing has been done, however all the results show the achievement still less comparable with the conventional raw milk processing, thermal pasteurisation.