5. Conclusion
The ethanolic extracts of frozen apple peel and oven-dried apple
peel were fractionated and the yield of total phenolics and flavonols
on DM basis was higher in the frozen peel indicating that
the drying process can impact some polyphenols. The fractionated
apple peel extract displayed a stronger inhibitory effect on fish oil
oxidation than BHT, a-tocopherol and the crude apple peel extract
itself. The fractions containing quercetin glycosides and epicatechin
in combination with other polyphenols, such as phloridzin
and cyanidin-3-O-galactoside, showed the greatest antioxidant
capacity. Further investigations are needed to fully reveal the synergistic
effect of different combinations of active polyphenols in
the inhibition of fish oil oxidation.