Publications

Selected publication  

Liu D., Lescano-Osorio O.F., Nikiforov A., De Geyter N., Machala Z., De Meulenaer B.: Effects of emulsion pH and gas humidity on non-thermal plasma-induced lipid oxidation in oil-in-water emulsions, Innovative Food Sci. Emerging Technol. 114 (104828), 1-9 (2026).
citations: 0

Abstract

Non-thermal plasma (NTP) treatment has been researched as a food preservation technique, while lipid oxidation remains one of its concerns. In this study, oil-in-water emulsions were selected as the model system for plasma treatment to investigate the interaction between plasma induced chemistry in the aqueous phase and lipid oxidation. O/W emulsions were prepared with 10 wt% sunflower oil and 90 wt% 0.1 M phosphate solution with a pH range from 1.0 to 12.0. After dry air plasma treatment, the pH of the phosphate solution decreased mainly due to the dissolution of reactive nitrogen species in water, especially under alkaline conditions. Nitrate (NO3−) was the dominant species in the plasma-treated phosphate solutions. The peroxide value of extracted lipids demonstrated a bipolar distribution with peaks at pH 3.0–4.0 and 9.0, while the formation of volatile oxidation products gradually decreased as pH levels elevated. Humid air plasma enriched the amounts of H2O2 and NO2− in the liquid but lowered the level of lipid oxidation, suggesting that peroxynitrous acid chemistry contributed little to the oxidation process. Lipid oxidation in emulsions was related to the dissolution of gaseous reactive species, followed by their interactions and decomposition in the aqueous phase. The changes in pH and solute concentration affected the ionic strength, which influenced the solubility of gaseous species. O3 is found to be the most influential species, and its concentration in the gas phase likely controls the amount of dissolved O3 in the emulsions, thereby affecting the lipid oxidation.