Intelligent use of ethanol for the direct quantitative determination of volatile compounds in spirit drinks

The quality of any alcoholic beverage depends on many parameters, such as cultivars, harvesting time, fermentation, distillation technology used, quality and type of wooden barrels (in case of matured drinks), etc.; however, the most important factor in their classification is content of volatile compounds. In accordance with the legislative official analysis methods of EU, USA, China, India the analysis of volatile compounds is performed by GC-FID with the traditional method of internal standard. This method has such disadvantages as additional error due to pipetting of the internal standard, the inconvenience of additional time required for counting, and contamination of the sample with IS.
In order to solve the described problems of the traditional IS method, a modified IS method has been developed. This method is based on the use of ethanol, the main volatile organic compound of any alcohol sample, as an IS.
The developed method was in-house validated for the direct quantitative determination of volatile compounds (acetaldehyde, methyl acetate, ethyl acetate, methanol, propan-2-ol,
propan-1-ol, butan-2-ol, 2-methylpropan-1-ol, butan-1-ol and 3-methylbutan-1-ol) in a wide range of alcoholic beverages with ethanol volume concentrations from 6.5 to 96.6 %. Spirit drinks (brandy, gin, rum, calvados, whiskey, bourbon, slivovice, tsikoudia, tequila, grappa), liquors (sweet, herbal and egg liquors), national Belarussian alcoholic beverages (strong drink, grain spirit, nalewka, cocktail, krupnik, bitter and sweet tinctures) and other alcoholic beverages (vermouth, sake, mulled wine) were studied by both traditional and developed methods. The developed and traditional IS methods showed good accuracy with recovery values between 98.5-102.1 % and 98.2-103.0 %, correspondingly. The maximal values of relative standard deviation of repeatability and intermediate precision were 4.5 % and 5.9 % for the developed method; 4.8 % and 6.2 % for traditional method, correspondingly. The relative difference between results, obtained for both developed and traditional methods for studied alcoholic beverages didn’t exceed 1.5 %.
The developed method is simple, labor, less time-consuming and can be used for direct sample injection, which is the simplest and most attractive approach since no sample handling procedure is required and no loss of minor volatile compounds occurs. High efficiency and wide international testing of the method using ethanol as an internal standard can serve as the basis for initiating, in the established manner, interlaboratory study on the basis of specialized international organizations, for example, the International Organization for Standardization (ISO), the Codex Alimentarius Commission or the International Organization of Vine and Wine (OIV) for the purpose of its subsequent approval as a standardized reference method on the international level.

Authors: Charapitsa Siarhei1, Sytova Svetlana1, Kavalenka Anton1, Sobolenko Lidia1, Zayats Mikhail2, Egorov Vladimir2 and Leschev Sergey2

1Institute for Nuclear Problems of Belarusian State University
2Belarusian State University

*corresponding author:

Keywords: alcoholic beverages, volatile compounds, ethanol, referee method of OIV

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