Abstract
A partial or even complete substitution of icewines by other wines of high quality but harvested under non-icewine conditions has to be anticipated in vintages of unfavorable mild winters. Although stable isotopes reflect incomplete phase transitions and are therefore potentially well suited for icewine authentication, this technique has not yet been applied as an analytical tool against icewine frauds. As a first approach, this study shows that icewine authentication is best achieved by measuring the difference of δ18O values between the water of icewine musts and the remaining water in their grape marcs. A positive difference indicates a fraud. Furthermore, this difference was found to be related to the increase in sugar in the must due to cryoconcentration. Hence, this difference also allows estimation of the extent of cryoenrichment. By measuring 47 commercially produced icewine musts and their corresponding grape marcs, an average difference of ~1.7‰ was observed in vintage 2012 in Germany. This difference corresponds to an average cryoenrichment of ~150% (i.e., an increase over the initial must weight by a factor of 1.5).
- ©2014 by the American Society for Enology and Viticulture
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