title: Effects of must concentration techniques on wine isotopic parameters.
abstract: Despite the robustness of isotopic methods applied in the field of wine control, isotopic values can be slightly influenced by enological practices. For this reason, must concentration technique effects on wine isotopic parameters were studied. The two studied concentration techniques were reverse osmosis (RO) and high-vacuum evaporation (HVE). Samples (must and extracted water) have been collected in various French vineyards. Musts were microfermented at the laboratory, and isotope parameters were determined on the obtained wine. Deuterium and carbon-13 isotope ratios were studied on distilled ethanol by nuclear magnetic resonance (NMR) and isotope ratio mass spectrometry (IRMS), respectively. The oxygen-18 ratio was determined on extracted and wine water using IRMS apparatus. The study showed that the RO technique has a very low effect on isotopic parameters, indicating that this concentration technique does not create any isotopic fractionation, neither at sugar level nor at water level. The effect is notable for must submitted to HVE concentration: water evaporation leads to a modification of the oxygen-18 ratio of the must and, as a consequence, ethanol deuterium concentration is also modified.
authors.affiliation: Laboratoire de Bordeaux, Direction Générale de la Concurrence, de la Consommation et de la Répression des Fraudes, 3 avenue du Dr. A. Schweitzer, 33608 Pessac, France. labo33@dgccrf.finances.gouv.fr
authors.forename: Francois
authors.initials: F
authors.lastname: Guyon
authors.forename: Christine
authors.initials: C
authors.lastname: Douet
authors.forename: Sebastien
authors.initials: S
authors.lastname: Colas
authors.forename: Marie-Hélène
authors.initials: MH
authors.lastname: Salagoïty
authors.forename: Bernard
authors.initials: B
authors.lastname: Medina
mesh_terms: D002247:Carbon Isotopes / Q000032:analysis; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003903:Deuterium / Q000032:analysis; D005511:Food Handling / Q000379:methods*; D005638:Fruit / Q000737:chemistry*; D007554:Isotopes / Q000032:analysis*; D009995:Osmosis; D010103:Oxygen Isotopes / Q000032:analysis; D014618:Vacuum; D027843:Vitis / Q000737:chemistry*; D014920:Wine / Q000032:analysis*
chemical_list: D002247:Carbon Isotopes; D007554:Isotopes; D010103:Oxygen Isotopes; D003903:Deuterium