Revealing the inhibitory mechanism of ferulic acid on rice lipase via structural and kinetic analyses under cold plasma treatment during storage.

Abstract

Lipid hydrolysis catalyzed by endogenous lipases is a major contributor to quality deterioration in stored rice. This study aimed to elucidate how cold plasma (CP) treatment affects lipid stability by examining changes in lipase activity, structure, and endogenous ferulic acid (FA) during storage. After 60 days, CP-treated rice showed a 15.8% increase in FA content, accompanied by a 22.4% reduction in lipase activity and an approximately 25% decrease in free fatty acid value compared with the control. FT-IR spectroscopy revealed alterations in lipase secondary structure, including decreased α-helix (2.1%) and β-sheet (5.7%) and an increased random coil content (12.7%). Molecular docking confirmed FA binding within the active site via hydrophobic/hydrogen bonds, sterically hindering substrate access. Enzyme kinetic analysis showed that FA decreased V_max while increasing K_m, indicating mixed-type inhibition. Overall, CP treatment is associated with coordinated regulation of lipase structure and activity, contributing to improved lipid stability during storage.