Antioxidant activity and bioactive compounds of cocoa and chocolate

Cocoa and chocolate are recognised for their bioactive compounds like methylxanthines and phenolic compounds, their nutritious and functional qualities are related, among other factors, to cocoa variety, geographical region, climatic and processing conditions. Two cocoa samples from Peru (Chuncho and Piura Blanco), one from Africa (S. Tomé), and the dark chocolates produced from these cocoa samples were studied in terms of antioxidant activity, phenolic compounds and methylxanthines. A physicochemical and functional characterization was performed through the antioxidant activity and total phenolic compounds content by colourimetry and the methylxanthines contents (theobromine, caffeine and theophylline) by HPLCPDA. The methanolic extracts presented higher contents of total phenolic compounds ranging form 1082.9 mg GAE/100g in S. Tomé cocoa to 813.4 mg GAE/100g in its dark chocolate. The values for antioxidant activity ranged from 3077.2 to 3159.2 μmol TE/100g (DPPH test), 2279.4 to 2290.0 μmol TE/100g (ABTS test), and 1936.5 to 3981.0 μmol TE/100g (FRAP test). Theobromine presented the highest results for the methylxanthines bioactive compounds, being higher in S. Tomé cocoa (1097.0 mg/100g) and lower in Chuncho chocolate (516.24 mg/100g). Regarding caffeine, the Chuncho cocoa presented the highest content (245.54 mg/100g), while S. Tomé chocolate presented the lowest (46.79 mg/100g). The theophylline could only be quantified in S. Tomé cocoa (6.85 mg/100g), due to its low values in these food matrices, being only identified in the remaining samples. All samples presented a considerable number of phenolic compounds, antioxidants and at least two methylxanthines, proving that chocolate and cocoa are functional foods and a source of bioactive compounds.