The Design, Construction, and Preliminary Analysis of an Atmospheric Pressure Cold Plasma Jet System for the Processing of Bovine Milk

Abstract

While thermal pasteurization is by far and away the predominant method used to sterilize liquid cow’s milk, this form of processing requires the application of heat to milk, unfavorably altering the milk physiochemically and organoleptically. Alternative technologies to thermal pasteurization have been explored including the use of X-ray and UV radiation, pulsed electric field technology, membrane microfiltration and the application of nonthermal (cold) plasma. Cold plasma systems, in their applications with bovine milk, have previously been used as a surface treatment or in dielectric barrier discharge treatment of milk. This research work discusses a novel configuration used to apply atmospheric cold plasma to liquid milk for pasteurization by bubbling the cold plasma through the liquid milk, the steps taken to design and build a benchtop prototype, some preliminary analyses done on processed raw milk samples, and direction for future research and evaluation of this technology for on-farm or industrial use. FTIR compositional analysis showed no statistically significant changes to the constituents of the milk following cold plasma processing. Protein profiling showed slight interaction of kappa casein and beta lactoglobulin, though no other significant changes to protein subunits were observed. Microbial analyses did not show significant reduction of microorganisms with cold plasma processing. Future work should focus on optimization of operating parameters. Once optimized, the designed configuration holds promise for industrial application, especially to be used in scaled-up applications and could be used in conjunction with thermal pasteurization to reduce milk waste through self-life extension or even one day replace thermal pasteurization in the dairy industry as the primary methodology used to cold pasteurize cow’s milk.