The Use Of Stable Isotopes In Quantitative Determinations Of Exogenous Water And Added Ethanol In Wines

摘要

The application of oxygen isotope ratios analysis to wine water according to EU regulation no. 822/97 to determine wine's origin and also, the possible water addition to wines, gained great importance in wines authenticity control. In the natural cycle of water isotopic fractionation, during water evaporation process, the water vapors are depleted in heavy isotopes. On the other hand inside the plants take place an isotope enrichment of heavy stable isotopes of water compared with meteoric water due to photosynthesis and plants transpiration. This process makes possible the detection of exogenous water from wines ~(18)O/~(16)O ratios. Carbon isotopic ratios were used to estimate the supplementary addition of ethanol obtained from C_(4) plants (sugar cane or corn). This work presents the way in which the isotopic fingerprints (delta~(13)C and delta~(18)O) were used to determine the content of exogenous water from wines and the added supplementary ethanol coming from C_(4) plants. By using this method, the calculated values obtained for the degree of wine adulteration were in a good agreement with the real exogenous percent of water and ethanol from investigated samples.