Inhibition of hemoglobin-mediated lipid oxidation in washed fish muscle by cranberry components

Fractions enriched in phenolic acids (Fraction 1), anthocyanins (Fraction 2), flavonols (Fractions 3 and 4) and proanthocyanidins (Fractions 5 and 6) were prepared from cranberry powder using Sephadex LH-20 chromatography. Fractions 2, 3, 4, and 5 had nearly equivalent reactivity in the total phenolate assay employed per mg dry weight of each fraction while Fractions 1 and 6 were less reactive. The ability of cranberry fractions to scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals as well as their inhibitory effects on hemoglobin (Hb)-mediated lipid oxidation in washed cod muscle were assessed. Addition of cranberry fractions at a level of 74 μmol quercetin equivalents per kg of washed cod muscle extended the induction time of thiobarbituric acid reactive substances (TBARS) formation in the order: Fraction 1, Fraction 3, Fraction 4 > Fraction 2 > Fraction 5 > Fraction 6. This suggests that oligomeric polyphenols (e.g., proanthocyanidins) were least effective at inhibiting Hb-mediated lipid oxidation in washed cod muscle compared to the other classes of polyphenolics in cranberry. The ability of the different cranberry fractions to scavenge DPPH radicals did not reflect their relative ability to inhibit lipid oxidation in the washed cod muscle system. Quercetin was tentatively identified as a component in cranberry that was especially effective at inhibiting Hb-mediated lipid oxidation. The ability of flavonol and proanthocyanidin-enriched fractions to inhibit Hb-mediated lipid oxidation in spite of efforts to wash away the added polyphenolics prior to Hb addition indicated these classes of polyphenolics had binding affinities for insoluble components of washed cod muscle.