Impact of Nonthermal Plasma on Lipid Oxidation from the Perspective of Plasma Treatment Parameters and Plasma Species: Identification of Key Reactive Species

Nonthermal plasma is a mild processing technology for food preservation. Its impact on lipid oxidation was investigated in this study. Stripped methylesters were considered as a basic lipid model system and were treated by a multihollow surface dielectric barrier discharge. In dry air plasma, O₃, ^·NO₂, ^·NO₃, and ¹O₂ were identified as the main reactive species reaching the sample surface. Treatment time was the most prominent parameter affecting lipid oxidation, followed by the (specific) power input and the plasma-sample distance. In humid air plasma, less O₃ was detected, but ONOOH and O₂NOOH were generated and presumed to play a role in lipid oxidation. Ozone mainly resulted in the formation of carbonyl substances via the trioxolane pathway, while reactive nitrogen species (i.e., ^·NO₂, ^·NO₃, ONOOH, and O₂NOOH) led to the formation of hydroperoxides. The impact of short-living radicals (e.g., ^·O, ^·N, ^·OH, and ^·OOH) was restricted in general, since they dissipated too fast to reach the sample.^·NO, HNO₃, H₂O₂, and UV radiation did not induce lipid oxidation. All the reactive species identified in this study were associated with the presence of O₂ in the input gas.