Comparison of antioxidant properties of phenolic compounds and their effectiveness in imparting oxidative stability to sardine oil during storage

• Six phenolic compounds were studied for their antioxidant potential.
• Relationship between structure and the antioxidant potential has been established.
• Oxidative stability imparted by each one in sardine oil during storage was assessed.
• Quercetin showed highest oxidative stability to sardine oil followed by Rutin.

Six phenolic compounds belonging to two different classes (hydroxycinnamic acids and flavonoids) were chosen for the study with the aim to identify the ones which gives highest oxidative stability to the sardine oil. Initially, DPPH (2,2-diphenyl-1-picryl hydrazyl) scavenging activity, ferric reducing antioxidant power (FRAP) and metal chelating activity of all the antioxidants were determined through in vitro studies. Among all, quercetin showed the maximum DPPH activity, caffeic acid gave the maximum FRAP and catechin showed the highest metal chelating activity. Protective effect of all the phenolic compounds in stabilizing sardine oil were evaluated further, on the basis of peroxide values, p-anisidine value, conjugated dienes and thiobarbituric acid reactive substances during storage. Results showed that quercetin and rutin followed by caffeic acid were effective in restraining sardine oil oxidation. Ferulic acid and sinapic acid showed mild improvement in oxidative stability, whereas catechin had no effect.