Polyphenols, methylxanthines, and antioxidant capacity of chocolates produced in Serbia

Different kinds of chocolates produced in Serbia were analyzed regarding total polyphenol, flavonoid and proanthocyanidin content using spectrophotometric methods. Flavan-3ols and methylxanthines in all samples were determined with RP-HPLC. DPPH, FRAP, ABTS and ORAC assays were applied for measuring antioxidant capacity. The average of all four antioxidant tests for each cocoa product was used for calculating antioxidant potency composite index (ACI). Obtained results for all four assays have shown that antioxidant capacity of analyzed chocolate/cocoa extracts followed cocoa, polyphenol, flavonoid, and proanthocyanidin contents. Although the addition of raspberries to dark chocolates had no significant influence on their total polyphenol, flavonoid and proanthocyanidin contents, statistical analysis showed that there was significant increase in the antioxidant capacity of dark chocolates with raspberry compared to plain dark chocolates (p = 0.007). Overall range for theobromine content varied from 5.5 to 22.3 mg/g depending on the product type, while the content of caffeine was 13-30 times lower in all analyzed cocoa products. In addition, correlation between antioxidant potency composite index and declared percentage of cocoa was high (R-2 = 0.798,p lt 0.05) and indicated that declared cocoa content was a reliable indication for antioxidant capacity of chocolates produced in Serbia