Alkyl chain length impacts the antioxidative effect of lipophilized ferulic acid in fish oil enriched milk

• EPA and DHA concentrations did not change in fish oil enriched milk during storage.
• Influence of the chain length on the efficacy of alkyl ferulates as antioxidants.
• Methyl ferulate is the most efficient antioxidant in fish oil enriched milk.
• Octyl and dodecyl ferulates acted as prooxidants in fish oil enriched milk.

Lipophilization of phenolics by esterification with fatty alcohols may alter their localization in an emulsion and thereby their antioxidant efficacy. In this study, synthesized unbranched alkyl ferulates were evaluated as antioxidants in fish oil enriched milk. Lipid oxidation was determined by peroxide values and concentration of volatile oxidation products. A cut-off effect in the antioxidant efficacy in relation to the alkyl chain length was observed. The most efficient alkyl ferulate was methyl ferulate followed by ferulic acid and butyl ferulate, whereas octyl ferulate was prooxidative and the prooxidative effect increased further with an increment in the alkyl chain length from C8 to C12. Further elongation of the alkyl chain length to C16 and C20 resulted in weak prooxidative effects to weak antioxidative effects depending on the different volatile oxidation compounds developed.