[Determination of the percentage of grain whisky in commercial whiskies by isotopic mass spectrometry].

Commercial whisky is generally a blend between malt whisky and grain whisky. Corn is one of the main sources of grain and it is now well known that in corn the carbon dioxide assimilation proceeds through carboxylation of phosphoenolpyruvate but in many other plants like barley atmospheric carbon dioxide is fixed on ribulose 1,5 diphosphate. Each pathway of carbon dioxide assimilation is characterized by a fractionation factor of carbon isotopes. Consequently, the organic matter and also the fermentation alcohol of corn or barley show different 13C/12C ratio. The determination of the 13C/12C ratio in the alcohol of blended whisky allows the determination of the percentage of corn whisky.