engleski

Electrochemical and spectrophotometric determination of total polyphenol content in Croatian ancient apple varieties

Polyphenols are natural antioxidants since they have a potential to show anti-inflammatory, antiallergic, anticancer and antihemorrhagic properties. They are often found in fruit and vegetables in free and bound form as esters or glycosides. Many epidemiological studies suggest that regular consumption of fruits and vegetables rich in polyphenols may reduce the risk of cancer and cardiovascular diseases. Recent studies have shown that the ancient apple varieties are a rich source of polyphenols. Since polyphenols as antioxidants are able to donate electrons, they are easily oxidized at inert electrodes which enables their detection with electrochemical methods.The purpose of this study, was to investigate oxidation mechanism of quercetin in three different electrolytes (KCl, NaCl an LiCl) by cyclic and differential pulse voltammetry in order to find optimal electrolyte for the total polyphenol content determination. The results were applied to total polyphenol content determination in apple peel extracts of ancient Croatian apple varieties (Lještarka, Ljetna rebrača, Slavonska srčika, Zimnjara, Adamova zvijezda, wild variety (crabapple)), since those extracts mostly contain quercetin derivatives. Results obtained by differential pulse voltammetry (dpv) were compared to results obtained with spectrophotometric Folin-Ciocalteu (FC) method. Very high correlation for total polyphenol (TP) content obtained by two methods was observed since the TPdpv/TPFC ratio was around 1 and a correlation coeficient (R2) for TPdpv vs. TPFC was 0.98. The highest total polyphenol content was found in Slavonska srčika variety.

electrochemistry, spectroscopy, total polyphenol content determination

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