Exploring the Role of Various Feed Gases in Cold Plasma Technology: A Comprehensive Review

In the last decade, the contribution of non-thermal technology for providing safe and nutritious food has increased. Therefore, food scientists have put effort into developing and applying non-thermal technology to meet the ever-increasing demand for healthy food. The cold plasma is an emerging non-thermal technology for food processing that uses electrons, radicals, and ions generated at ambient temperature for inactivating microorganisms and enzymes. This technology encompasses various process parameters, such as power or potential difference, frequency, feed gas, and treatment time. The choice of feed gas can significantly influence the effectiveness of plasma exposure and its effect on different food constituents. For instance, the plasma using noble gas as feed gas preserved the physicochemical attributes (pH, TSS, TA, and color) and bioactive compounds of food but required a longer duration for enzyme and microbial inactivation. On the contrary, the oxygen and nitrogen-rich feed gas plasma generate an abundant amount of reactive oxygen and nitrogen species that alter the important physicochemical attributes and the functional components like vitamin C and phenolic compounds but are very efficient in inactivating the enzymes and microorganisms. This review briefs the readers about cold plasma, different equipment associated with its generation, reactive species generated specific to feed gas and feed gas interaction with other process parameters. Additionally, it elucidates the impact of different feed gases utilized in plasma formation on physicochemical characteristics, microbial eradication, enzyme inactivation, and bioactive compounds.