Non-thermal plasma pasteurization of milk using plasma technology (phase II)

Phase II of the research developed and tested a pilot scale prototype system and conducted extensive experiments to generate the required data to petition FDA approval of the technology. Data generated during the study enhanced the scientific understanding of this novel process, and provided technical information on the effects of the treatment on inactivation of microbes, enzymes and quality of fresh milk. These data can also be used in commercial equipment and process development. The outcome of this study is designed to assess and confirm both technical and economical feasibilities, and speed up the potential commercialization of this innovative technology in the dairy industry. BACKGROUND Phase I of this project (funded by DMI, 2005-2006) proved our hypothesis that the non-thermal plasmabased dielectric barrier high intensity electric field can inactivate microbes in milk, non-thermally at atmospheric pressure on a lab scale, and also developed and tested a unique designed based on the hypothesis. Phase II of this project further demonstrated the feasibility of this technology on a larger scale. Research focused processing variables and its on bacterial reduction and enzyme inactivation in milk. A a newly designed cylindrical high electric field and plasma reactor was used for this study. The study was designed to answer several key technical questions important to the commercialization of the technology: (1) Can high electrical field be generated in the large scale treatment chamber with practically available power supplies? (2) Is it possible to obtain uniformly distributed electrical field within the treatment volume in the large scale treatment chamber? (3) What are the processing parameters to ensure optimal microbial kill and enzyme inactivation and minimum quality impact with continuous processing in larger scale? During a previous study the effects on bacterial kill were examined using several different techniques such as various dielectric barrier materials, different reactor structures, several electrical field strength and frequency levels, and many types of liquid samples (water with different conductivity and milk with different dilutions). It was found that the bacterial kill was largely dependent upon the dielectric constant of the dielectrics, electrical field strength, and the conductivity of the samples. We also found that the electrical field strength can be greatly affected by the arrangement and structure of the electrodes. Our data indicates that this new technology overcomes two major defects in traditional pulsed electrical field (PEF) process: the high cost of pulsed power supply, and electrode erosion and contamination. Based on the experimental data, and discussions with directors at DMI and the Midwest Dairy foods Research Center, and industry partners, we concluded that a reactor combined