Integrated lipidomic and transcriptomic analysis reveals the effect of cold plasma treatment on lipid oxidation in...

Millet lipids exhibit a wide compositional range of 1 % to 7 %, predominantly consisting of neutral lipids, phospholipids and glycolipids. Among them, unsaturated fatty acids account for more than 60 %. However, dehulled millet is prone to lipid oxidation during storage, leading to quality degradation. This study evaluated the impacts of cold plasma (CP) on millet lipid oxidation. Results showed that CP treatment at 30 kV for 20 min effectively maintained the appearance quality of millet, reduced MDA content, and fatty acid values, and improved its antioxidant capacity. Lipidomics revealed that glycerophospholipids consistently decreased, whereas diglycerides, triglycerides, and ceramides increased in millet by CP treatment during storage. Integrated transcriptomics demonstrated that the up-regulation of the PLD1_2 gene promoted the phosphatidic acid production before storage, while the expression of several key genes related to lipid oxidation (PLD1_2, TGL4, LOX2S, and LOX1_5) was significantly down-regulated after 24 days of accelerated storage. Glycerophospholipid and glycerolipid metabolism were critical pathways. CP treatment significantly decreased the activities of lipase, lipoxygenase, and peroxidase in millet by 19.17 %, 18.34 %, and 17.56 %, respectively, thereby effectively retarding the progression of lipid oxidation during millet storage.