Ultrasound-Assisted Method for Extraction of Theobromine and Caffeine from Cacao Seeds and Chocolate Products

An ultrasound-assisted method for extraction of theobromine (TB) and caffeine (CF) from cacao seeds and chocolate products was developed. This extraction was carried out in 100 mL of heated water at 80 °C by using a 12.7-mm i.d. ultrasound probe and applying 240 W of power for 180 s. In order to quantify TB and CF, the aqueous extracts were treated with Carrez reagent to remove interferences. Then, 10 mL of the aqueous extract was adjusted at pH 12.5 and 10 mL of chloroform solvent was added. Ultrasound radiation was applied at 160 W of power for 30 s in order to transfer CF to the organic phase. The resulting emulsion was centrifuged at 6,000 rpm for 5 min to separate the phases. The photometric monitoring was at 276 nm for CF and at 273 nm for TB. This extraction method is simpler than the conventional liquid–liquid extraction which uses separatory funnels, and obtains similar results. By applying ultrasound in cacao seeds, the efficiency of extraction increased by 57.7 % for CF and 43.6 % for TB and by between 12 and 23 % for both analytes in chocolate products, in comparison with those results obtained by a conventional stirring extraction method.