In its gaseous form, carbon dioxide is utilized for many applications in the brewing and beverage industry, for example, to purge containers and to carbonate beverages.
Where the Reinheitsgebot, or the German purity law concerning beer, is observed, the carbon dioxide used to carbonate the beer must be generated during the fermentation process at one’s own brewery.
The most important role of carbon dioxide in the area of draft dispensing is as compressed gas for the purging the containers used to transport beverages [1]. Other gases such as nitrogen and carbon dioxide/nitrogen mixtures are also used as a protective gas in the transport of liquids.
Since the gases come into direct contact with the product, it is imperative that they be free of oxygen, foreign odors, oils, fats and oxidizable components, which have the potential to change the flavor or other properties of the beverage. Furthermore, microbiological purity must also be guaranteed.
The minimum scope of the analysis for CO2 and other technical gases are described in the MEBAK guideline “Beverage Dispensing Systems” [2]. Additional analyses can be found in the specifications from the Coca-Cola company [3] as well as the collection of analysis methods from the Verband Deutscher Mineralbrunnen [4].
In order to ensure due diligence, it is necessary to identify the origin of purchased carbon dioxide gas. Carbon dioxide can originate from natural sources, through fermentation or through combustion of fossil fuels, for example, from garbage incineration facilities. In some instances, this can lead to changes in the flavor of the beverage. In case of doubt, the origin can be determined on the basis of the 13C/12C isotope ratio [5].
Two compressed gases are approved and suited for dispensing beverages: carbon dioxide (CO2) and nitrogen (N2) or a mixture of both. These gases must fulfill a number of requirements.
References
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K.-H. Schnoor, Die Kohlensäure in der Getränkeindustrie, Getränkeindustrie 33 (9), 839–847, 1979
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MEBAK-Richtlinie Getränkeschankanlagen, Freising-Weihenstephan, 2010
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Coca-Cola-Vorschrift, Spezifikation für Kohlendioxid (Kohlensäure) E 180 vom 20. 12. 1989
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Verband Deutscher Mineralbrunnen e. V., Rundschreiben Nr. 41/97/98 vom 03. 07. 1998 mit Anlage
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J. Dunbar, Use of 13C/12C Ratios for Studying the Origin of CO2 in Sparkling Wines, Fres. Z. Anal. Chemie 311, 578–580, 1982
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E. Dachs, Mikroorganismen in der Kohlensäure?, Das Erfrischungsgetränk 31 (39), 760–768, 1978
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