The effects of corona discharge from a cold plasma source on the physicochemical properties and shelf-life of milk

Abstract

Milk is a nutrient-rich food and a risk source of foodborne pathogens, yet traditional thermal processing/pasteurization can affect its nutritional value. However, recently, consumer demand for healthy, fresh, and safe “green process” foods has increased, so emerging non-thermal food cold plasma (CP) technology has largely addressed consumer demands for safe and healthy foods by effectively eliminating pathogens from milk. In this study, we examined CP treatment duration (0, 1, 5, and 10 min) and membrane filtration (MF) effects on whole and skim milk with respect to milk characteristics, microbial growth, and xanthine oxidase activity over a 0– 15-day storage period. This study revealed that the shelf life of whole milk and MF skimmed milk with CP10 min amounted to 15 days and that the TPC was <6 log colony forming units (CFU/mL), while titratable acidity was <0.18% in compliance with regulatory standards, with insignificant color changes. Additionally, pH and lipid oxidation values in CP and MF groups were positively correlated with storage time (p < 0.05). Thus, CP treatment released free lipids into milk, with minor oxidative reactions. Critically, no significant effects were observed in terms of nutritional value and xanthine oxidase activity. Hence, we provide valuable processing insights for dairy manufacturers and show that CP10 min treatment positively impacted total plate count (TPC) and thermo-resistant bacteria. Our goal is to reduce the heat load on milk without compromising nutritional quality while maintaining food safety.