Carbon-13 composition of bulk dry wines by irm-EA/MS and irm-¹³C NMR: An indicator of vine water status

¹ Service Commun des Laboratoires, 3 Avenue du Dr. Albert Schweitzer, 33608 Pessac Cedex, France
² EGFV, Bordeaux Sciences Agro, INRA, Univ. Bordeaux, 33140 Villenave d'Ornon, France
³ EBSI Team, CEISAM, UMR CNR6230, 2 rue de la Houssinière, BP. 92208, 44322 Nantes Cedex 3, France

Abstract

Measurements performed on a set of 32 authentic wines (not submitted to any oenological treatment) and their ethanol, recovered by distillation, show high correlation between δ¹³C of bulk wine and its ethanol. These measurements were performed by isotope ratio monitoring by mass spectrometry coupled to an elemental analyzer (irm-EA/MS). Then a series of wines produced by vines of which water status was assessed during the growing season with predawn leaf water potential measurements, was studied by irm-EA/MS. As expected δ¹³C is correlated to vine water status conditions, as a result of stomatal closure. The ethanol of these specific wines was also analyzed by isotope ratio monitoring and by nuclear magnetic resonance (irm-¹³C NMR) to determine carbon-13 composition on the two specific sites of the ethanol skeleton. If these measurements confirm the correlation between ¹³C composition and vine growth conditions, the ¹³C stereospecific information does not make vine water status assessment more precise.