Effect of Enzyme Treatments and Drying Temperatures on Methylpyrazine Content in Cocoa (Theobroma Cacao L.) Powder Extract

The effects of combining enzyme treatments and heating protocols on pyrazine formation in cocoa powder extracts have been studied. Five commercial enzyme preparations containing protease and carbohydrase activities were initially assessed for their ability to release amino acids and reducing sugars, both of which are substrates for Maillard reactions. The enzyme preparation Flavourzyme was subsequently selected for further study given its ability to liberate both types of substrate. Cocoa powder solutions were treated with 2 doses of Flavourzyme and processed at 2 drying temperatures. The combination of the higher dose of the enzyme (12% w/w enzyme/substrate) and the higher drying temperature (150 °C) resulted in a synergistic increase in the concentration of methyl- and dimethylpyrazines. A statistically significant increase in the concentration of tetramethylpyrazine occurred in samples treated at 150 °C that was independent of the enzyme dose assayed. No significant changes in trimethylpyrazine content were detected in treated compared to untreated samples.