COLD PLASMA PROCESSING OF LIQUID FOODS: MECHANISMS, APPLICATIONS, AND FUTURE PERSPECTIVES

Abstract

Cold plasma (CP) is an emerging non-thermal technology that has gained attention for the preservation of liquid foods because of its ability to inactivate microorganisms while operating at relatively low temperatures. This review summarizes the principles, plasma systems, applications, and quality effects of CP treatment in liquid foods, with particular emphasis on fruit and vegetable juices, coconut water, and neera. The generation of reactive oxygen and nitrogen species during plasma treatment contributes to microbial inactivation through damage to cell membranes and intracellular components. Reported studies demonstrate substantial microbial reductions, including reductions of less than 5 log CFU/mL in selected fruit juices, together with inactivation of spoilage enzymes such as polyphenol oxidase, peroxidase, and pectin methylesterase. CP treatment can maintain several physicochemical and nutritional attributes under suitable conditions, although its effects on phenolic compounds, vitamins, pigments, proteins, sugars, colour, antioxidant activity, and sensory properties depend on plasma type, working gas, treatment intensity, and food composition. Applications in neera remain comparatively limited, although available studies indicate microbial reduction with relatively small changes in colour and total soluble solids. The review also discusses challenges related to plasma–food interactions, treatment uniformity, energy consumption, reactor design, gas selection, and storage stability. Future research should focus on matrix-specific process optimization, continuous-flow systems, energy-efficient treatment, and combinations with suitable packaging and refrigerated storage to improve the consistency and applicability of CP for liquid-food preservation.