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Phenolic composition of methanolic extracts and hydrolysates of chocolate

Recent evidence of the beneficial health effects of cocoa, due to its high content of bioactive compounds, has proven that chocolate provides more than just a delicious treat for the consumers. Literature data regarding the content of bioactive compounds in commercial types of chocolate are lacking, which indicates the necessity for compositional analysis of these frequently consumed products. The objective of this study was to assess the phenolic content of methanolic extracts prepared from seven commercially available chocolates with different cocoa solids content (dark, semisweet baking, powdered and milk chocolate) and to compare the effect of acid hydrolysis on the phenolic content of methanolic chocolate extracts. The content of total phenols, flavonoids and flavan-3-ols of selected products was determined spectrophotometrically, while the phenolic and methylxantines composition was determined by high performance liquid chromatography (HPLC-PDA). The highest content of total phenols (32.03 mg GAE/g of defatted chocolate), flavonoids (16.60 mg GAE/g of defatted chocolate) and flavan-3-ols (10.48 mg (+)-catechin/g of defatted chocolate) was determined in dark chocolate (88% cocoa dry matter), followed by dark chocolates with 72% and 60% cocoa dry matter, semisweet, milk and powdered chocolate. In comparison with methanolic extracts, hydrolysates showed significantly lower values of total phenol, flavonoid and flavan-3-ol content. Opposite to the content of theobromine, as the most abundant phytochemical in chocolate (12.64 mg/g of defatted chocolate with 88% of cocoa dry matter), the content of caffeine was almost 10 fold lower in all chocolates. The most abundant polyphenolic compounds in chocolate were EC and GC, with the highest values determined in dark chocolate with 88% cocoa dry matter (1.87 and 1.13 mg/g of defatted chocolate, respectively). The obtained results will be used to promote the production and consumption of chocolate rich in natural antioxidants, thereby contributing to a complete modern diet which is often inadequate.

Chocolate; hydrolysis; methylxanthines; polyphenols

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