The “Wine-T₁” NMR experiment for novel wine-metabolome fingerprinting with nuclear-spin relaxation

¹ Consejo Nacional de Ciencia y Tecnología-Laboratorio Nacional de Investigación y Servicio Agroalimentario y Forestal. Universidad Autónoma Chapingo. Carretera México-Texcoco Km 38.5, C.P. 56230, Chapingo, Estado de México, Mexico
² Laboratorio Nacional de Investigación y Servicio Agroalimentario y Forestal. Universidad Autónoma Chapingo. Carretera México-Texcoco Km 38.5, C.P. 56230, Chapingo, Estado de México, Mexico
³ Departamento de Química Orgánica, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional. Prolongación de Carpio y Plan de Ayala s/n, Colonia Santo Tomás, 11340 Ciudad de México, Mexico
⁴ Consejo Mexicano Vitivinícola A.C. Montecito No 38 Piso 15 Despacho 22 – WTC México, C.P. 03810, Ciudad de México, Mexico

Abstract

In agreement with the draft resolution OENO-SCMA 17-618 at step 5 “Quantitation of glucose, malic acid, acetic acid, fumaric acid, shikimic acid and sorbic acid in wine using proton nuclear magnetic resonance spectroscopy (¹H NMR)” said technique has been recently accepted within the OIV chair as a primary quantitative analytical technique for beverage analysis such as wine. However, poor chemical shift dispersion in ¹H NMR spectra severely penalizes quantification within overlapped or crowded regions. To outflank said penalization and quantify metabolites in signal overcrowding situations, the novel “Wine-T₁” experiment is proposed. The novel scheme comprises the addition of a second dimension, wherein the proton spin-lattice relaxation times (T₁-{¹H}) of each metabolite's spin-system is correlated to a chemical-shift dimension. The new experiment includes a water and ethanol signal pre-saturation module, prior to the T₁ saturation-inversion recovery dimension in order to maximize signal-to-noise ratio of wine metabolome NMR spectra. “Wine-T1” pulse sequence can be adapted to all commercial spectrometers (Bruker, Varian/Agilent, Jeol) and with acquisition times in the order of minutes, it should be considered as a fast repetition method to produce a robust metabolome fingerprint that has not been described before, to the best of our knowledge.