Multifunctional phenolics in flaxseed oil: Structures, antioxidant and antimicrobial bioactivities

This study hypothesizes that the structural forms of endogenous phenolics in flaxseed oil are linked to their antioxidant and antimicrobial activities, crucial for reducing lipid rancidity and extending food shelf life. Phenolics were analyzed using UPLC-ESI-Q-TOF-MS with alkaline hydrolysis, and their antioxidant and antimicrobial activities were evaluated through in vivo experiments. The results identified 335 phenolic compounds, predominantly in free (49.4 %) and insoluble-bound (31.9 %) forms. Antioxidant activity correlated with the total phenolic content (TPC) (99.0 mg gallic acid equivalents (GAE)/100 g) and flavonoid content (90.7 mg RE/100 g), exhibiting synergistic or antagonistic effects depending on the interactions among compounds. Additionally, the phenolic compounds inhibited the growth of Escherichia coli and Staphylococcus aureus, with esterified phenols showing particular effectiveness against Gram-positive bacteria. These findings confirm that the structural forms of phenolic compounds directly influence their bioactivities, supporting the potential application of flaxseed oil as a natural preservative in the food industry.