Extraction and determination of methylpyrazines in cocoa beans using coupled steam distillation-microdistillator

The formation of methylpyrazines was determined in fermented cocoa beans (Ivory Coast), in laboratory and industrially roasted samples. The determination of these methylpyrazines was studied by coupled steam distillation-microdistillation as the extraction method and gas chromatography using capillary column and a thermionic detector. The monomethyl-; 2,3-dimethyl-; 2,5-dimethyl-; 2,6-dimethyl-; trimethyl- and the tetramethylpyrazine were detected in non-roasted cocoa beans. Their concentration increased rapidly in laboratory roasted cocoa beans and industrial samples, only the tetramethylpyrazine showed a maximum peak of concentration. The principal compound was the tetramethylpyrazine in fermented and roasted cocoa beans. The determination of the different methylpyrazines in cocoa beans would permit both the evaluation of cocoa mass quality and the control of the cocoa roasting process.