Oenological influences on the D/H ratios of wine ethanol

摘要

Within the European Union the determination of chaptalization of wine involves the comparison of the D/H ratios of ethanol with the ratios of authentic wine samples that are similar to the suspect wine in terms of geographical origin, grape variety, and vintage. In the frame of a databank project comparison, wines are produced under official control on a small scale. To clarify the influence of the different production conditions between commercial wines and these databank wines, wines that were produced under varying conditions were investigated by the H-2 NMR method. None of the parameters under investigation, such as yeast strain, fermentation temperature, or wine fining, showed a significant influence on the (D/H)(I) ratio of wine ethanol, which is the most indicative parameter for the determination of the addition of extraneous sugar to wine. For the (D/H)(II) ratio, different values were found for different yeast strains used for fermentation and a slight decrease was observed with increasing fermentation temperature. At increasing points of fermentation yield an increase of the D/H ratios was found in the present alcohol. The total increase of the (D/H)(I) ratio throughout the fermentation was approximately 1 ppm, so that with a fermentation yield of more than 50% no statistical difference could be observed. [References: 19]