With the difference in the photosynthesis process between C3- and C4-plants, the
13C/
12C stable isotope ratio of ethanol, i.e., δ
13C-ethanol, can potentially be a basis for the discrimination of Scotch whiskies derived from different raw materials. This study
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With the difference in the photosynthesis process between C3- and C4-plants, the
13C/
12C stable isotope ratio of ethanol, i.e., δ
13C-ethanol, can potentially be a basis for the discrimination of Scotch whiskies derived from different raw materials. This study analyzed 51 authentic single malt Scotch whiskies and 34 authentic blended Scotch whiskies by gas chromatography–combustion–isotope ratio mass spectrometry (GC-C-IRMS) and examined the resulting data by a series of fitting distribution processes. The evaluation result demonstrated that δ
13C-ethanol distribution of single malt Scotch whiskies fitted both normal and 3-parameter lognormal distribution. For blended Scotch whiskies, however, the data distribution of δ
13C-ethanol conformed with a 3-parameter lognormal distribution rather than a normal one. Moreover, 99.7% of the confidence intervals (CI) of δ
13C-ethanol for single malt Scotch whiskies would define between −23.21‰ to −30.07‰ for 3-parameter lognormal distribution, while from −11.19‰ to −28.93‰ for blended Scotch whiskies on the basis of the statistical properties. The simulative adulterated Scotch whiskies using more than 30% C4-derived edible distilled spirits can be effectively discriminated by means of CI of δ
13C-ethanol. Since the addition of rectified spirits produced from the C4 plant has been found in some cases of seized Scotch whiskies in Taiwan, establishing a CI of δ
13C-ethanol would be valuable for the purpose of Scotch whisky authentication.
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