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

Francois Guyon,Marie-Hélène Salagoïty,Laetitia Gaillard,Cornelis Van Leeuwen,Gérald S Remaud,Mathilde Grand,Serge Akoka,Nathalie Sabathié

doi:10.1051/bioconf/20170902021

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 δ13 C 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 δ13 C 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-13 C NMR) to determine carbon-13 composition on the two specific sites of the ethanol skeleton. If these measurements confirm the correlation between 13 C composition and vine growth conditions, the 13 C stereospecific information does not make vine water status assessment more precise.

Highlights

Isotope fractionation in plants is well-known, for 18O and 2H and is a result of the water cycle [1]
Measurements performed on a set of 32 authentic wines and their ethanol, recovered by distillation, show high correlation between δ13C of bulk wine and its ethanol
Another study showed the average δ13C discrepancy between sugar and its ethanol, resulting from the fermentation process [4]. Because this shift is constant, ethanol δ13C can be used as an indicator of vine water status during grape ripening (Fig. 1)

Summary

Introduction

Isotope fractionation in plants is well-known, for 18O and 2H and is a result of the water cycle [1]. In vines, this fractionation is accentuated by transpiration during grape ripening. Another study showed the average δ13C discrepancy between sugar and its ethanol, resulting from the fermentation process [4] Because this shift is constant, ethanol δ13C can be used as an indicator of vine water status during grape ripening (Fig. 1). The aim of this study, previously published elsewhere [7], was to propose a rapid and reliable method directly applicable to wine, able to provide an estimation of grape ripening conditions with regard to vine water status

Methods

Results

Conclusion