| Abstract
| - The relationship between phenolic composition and radical scavenging activity of apple peel andpulp was investigated in fruit produced according to both organic and integrated agricultural methods.Apple tissue extracts were subjected to high-performance liquid chromatography separation, whichshowed that as compared with pulps, peels are richer in almost all of the quantified phenolics.Flavonols, flavanols, procyanidins, dihydrochalcones, and hydroxycinnamates were the identifiedphenolic classes in peel tissue, and the most abundant compounds were epicatechin, procyanidinB2, and phloridzin. Pulps were poorer in phytochemicals. Their major phenolics were procyanidinsand hydroxycinnamates. Flavonols in amounts <20 mg kg-1 fresh weight (fw) were also found. Inboth peels and pulps, integrated production samples were richer in polyphenols. Among the 14compounds identified, only phloridzin had a tendency to appear higher in organic peels. The totalantioxidant capacities (TAC) of extracts were evaluated using the 1,1-diphenyl-2-picrylhydrazyl radicalassay and were expressed as Trolox equivalents. Integrated peels gave the highest TAC (18.56 mMkg-1 fw), followed by organic peels (TAC = 14.96), integrated pulps (TAC = 7.12), and organic pulps(TAC = 6.28). In peels, the top contributors to the antioxidant activity were found to be flavonols,flavanols, and procyanidins, which accounted for about 90% of the total calculated activity whereasin pulps, the TAC was primarily derived from flavanols (monomers and polymers) together withhydroxycinnamates. A good correlation between the sum of polyphenols and the radical scavengingactivities was found. Among the single classes of compounds, procyanidins (in peels and pulps) andflavonols (in peels) were statistically correlated to the TAC. Keywords: DPPH; HPLC; organic apple; phenolics; antioxidant activity
|
