PRELIMINARY RESULTS ON ISOTOPIC METHODS FOR THE CONTROL OF WINES

Stela Cuna, Nicolae Palibroda, Gabriela Balas, Petre Berdea

National Institute of Research and Development for Isotopic and Molecular Technologies, Donath Str. 71-103, Cluj Napoca 400293, Romania

Isotopic methods have shown to be a major tool for checking the compliance of food products and beverages with national and international regulations [1], [2], [3]. 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 an  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.

References
[1] Guillou C., Reneiro F., Isotopic methods for the control of  foods products and beverages ,Proceeding of the  Advisory Group Meeting, 20-23 September  Vienna 1999, pp. 39-53, (1999).
[2] E.C. Regulation, Community analytical methods which can be applied in the wine sector, Nr. 2676/90, Official Journal of the European Communities, Nr. 272, vol. 33, pp. 64-73, (1990).
[3] Dunbar J., Use of 13C/12C ratios for studying the origin of CO2 in sparkling wines, Fresenius Z. Anal. Chem., 311, pp. 578-580, (1988).