Preliminary results on isotopic methods for the control of wines

Full text: Isotopic methods have shown to be a major tool for checking the compliance of food products and beverages with national and international regulations. This paper presents some results on isotopic methods for control of wines. We developed a method for determining 13C/12C and 18O/16O isotope ratios in wine's ethanol and water. These ratios are significantly influenced by geo-climatic conditions of the origin region of wine, the type of plant (species or subspecies), and the year of harvest. The determination of 13C/12C ratio of wine ethanol was performed in three steps: (I) 500 ml of a wine sample was distilled at constant reflux ratio, (10). The distillate was collected with an ethanol content of about 93 % (mass), without significant isotope fractionation; (II) The ethanol was converted into CO2 by combustion in excess of oxygen; (III) The carbon isotope ratio of CO2 was analyzed using the isotope ratio mass spectrometry (IRMS). The 18O/16O ratio of the wine water was determined by IRMS using CO2 obtained after equilibration of wine with carbon dioxide. We developed this method in order to get a data bank of isotope ratios for authentic samples of wine as well as for the routine control of many marketed wines. (authors)