A study of the physicochemical behaviour of diacetyl in hydroalcoholic solution with and without added catechin and wood extract.

The interactions of diacetyl and ethanol in model solutions were studied in order to improve understanding of the changes in flavor perception that occur during both alcoholic beverage processing and consumption. A gradual reduction was demonstrated in the activity and partition coefficients of diacetyl as the ethanol concentration in aqueous solutions increased. From a sensory point of view, this fact would be expected to cause an increase in the diacetyl sensory thresholds. The expected diacetyl sensory thresholds were calculated based on experimental determination of the diacetyl vapor pressure in ethanol-water solutions at different ethanol concentrations. These sensory thresholds were not measured but merely obtained by theoretical interpolations. No significant variations in the activity coefficients of diacetyl were observed in the presence of catechin. Conversely, the dissolution of wood extract at 40% ethanol caused a significant decrease in diacetyl vapor pressure. The addition of catechin and wood extract to 40% ethanol-water solution contributed to the interactions of ethanol and water measured by DSC analysis.