/ WÜRZE, BIER UND BIERMISCHGETRÄNKE / Getränke allgemein / Kohlendioxid

B-590.39.042 [2020-10] Carbon Dioxide in Beverages – Conductivity Measurement

Carbon dioxide (CO₂) is added to beverages, such as water and soft drinks, to create a tingling sensation on the tongue from the CO₂ coming out of solution. But also, for wine, sparkling wine and beer production, carbon dioxide is indispensable to keep oxygen out.

The quantity of dissolved carbon dioxide is an important quality attribute of beer. A satisfactory level of carbonation (bottom-fermented beer 0.40–0.60 % w/w, top-fermented beer 0.40–0.80 % w/w) contributes significantly to the perceived freshness and drinkability of beer. Beers containing little carbon dioxide taste flat. Additionally, the carbon dioxide in beer promotes the formation of foam. The flavor thresholds of the flavor and aroma components in beer are altered by the quantity of carbon dioxide in solution.

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Aufgabenstellung/Zweck

Determination of the concentration of dissolved carbon dioxide in carbonated beverages in tanks, lines, bottles and cans by means of thermal conductivity

Anwendungsbereich

This analysis is suitable for dissolved carbon dioxide in carbonated beverages in concentrations ranging from 0–6.9 g/l.

Prinzip

The thermal conductivity is measured in a small chamber, which is in turn separated using a semi-permeable membrane from the medium being measured. The diffusion through the membrane alters the thermal conductivity in the measurement chamber. The gas volume in the measurement chamber is completely replaced in 10–20 s cycles. The changes in the thermal conductivity over time are a function of the quantity of CO₂ diffusing across the membrane. Using this value and taking into account the temperature, the concentration in the medium being measured can be calculated. Other dissolved gases, such as nitrogen and oxygen, do not affect the result of the measurement, since either nitrogen or air is used to replace the gas in the measurement chamber [1].