engleski

Quantitation of polyphenols in Croatian traditional apple varieties

Apples are one of the most widely consumed fruits in the world and a significant source of various bioactive compounds such as polyphenols. Polyphenols are mainly responsible for the antioxidant activity of apples [1]. Twenty-three apple samples were extracted from dried fruits using 80% aqueous methanol to achieve acceptable extraction of polyphenols. The extracts were then analysed by HPLC-DAD and LC-MS /MS. Total polyphenol content (TPC) was measured by an optimized Folin-Ciocalteu assay and antioxidant activity were determined by the DPPH method. The TPC content varied from 378.15 to 326.49 mg/100 g dw depending on the cultivar. The results from HPLC-DAD show that three polyphenolic compounds were successfully identified by comparing their experimental UV spectra with those from the spectra library. In addition, other compounds with polyphenol-like spectra were detected but not identified. LC-MS/MS allowed the unequivocal identification and quantification of 8 compounds, namely catechin, procyanidin B1, procyanidin B2, epicatechin, quercetin-3-ß-glucoside, quercetin-3-rutinoside, chlorogenic acid, and astragalin. The use of chromatography in conjunction with a MS detector operating in tandem mode (MS/MS) provides the required sensitivity and selectivity of analytes and allows in-depth characterization of the polyphenolic profile of twenty-three apple cultivars, improving knowledge of bioactive compounds in traditional apple varieties. The sum of polyphenols in apple samples ranged from 9.6-1243.8 mg/kg dw. Chlorogenic acid is the main polyphenol with content ranging from 1.3-455.9 mg/kg dw, followed by procyanidin B1 and B2 (4.1- 357.7 mg/kg dw), catechin (0.7-311.8 mg/kg dw), epicatechin (1.7-243.6 mg/kg dw), quercetin-3- glucoside (1.0-230.7 mg/kg dw), astragalin (0.7-28.8 mg/kg dw), and quercetin-3-rutinoside (0.1-15.7 mg/kg dw depending on varieties.

Croatian traditional apples varieties ; polyphenols ; HPLC ; antioxidant activity

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