Carbonation monitoring of beverage in a laboratory scale unit with on-line measurement of dissolved CO2

The effervescence properties of carbonated drinks are subject to the concentration of carbon dioxide dissolved and its ability to be transferred from the liquid phase to the forming bubble. We report the construction of a small laboratory scale carbonation unit that allows the study of the solubility of carbon dioxide in various hydro-alcoholic media, differing in their compositions. This unit, which is a model of a real industrial one, measures the instant concentration of CO2, during the carbonation process, by means of a thermal conductivity detector. The carbonation kinetics of various samples, containing water, alcohol, sugar, proteins and free amino-acids, were studied. While sugar diminishes CO2 solubility and, consequently, carbonation kinetics, free amino-acids and proteins increase the concentration of carbon dioxide in the medium. A survey of the rheological properties of the samples showed that CO2 solubility modifications are not correlated with changes in the viscosity of the medium. This equipment could be helpful for soft drink bottlers for measuring the changes that may affect effervescence and consequently the visual and gustative perception of the beverage after modification of its composition. (c) 2004 Elsevier Ltd. All rights reserved.