A methyl salicylate glycoside mapping of monovarietal Italian white wines.

Abstract

Among the main plant secondary metabolites, glycosides have a key-role in wine chemistry. Glycosides are non-volatile complex composed of a non-sugar component (aglycone) bound to one or more carbohydrates. The hydrolysis of glycosides occurs mainly during the fermentation due to the enzymatic activity, and during the storage as a consequence of pH and temperature conditions. In the last scenario, the gradual release of aglycones contributes to the aroma evolution of wine. Methyl salicylate (MeSa) is a plant metabolite known to be a chemical marker of several cryptogamic diseases¹; however, it can be also found in wines produced from healthy grapes, whose presence provides a pleasant wintergreen and balsamic nuance, especially in aged wines^2,3. This volatile odor-active ester can be found, mainly bound to glycosides, into the skin and the stem of the grapes. MeSa in the free form is frequently present under the sensory threshold while in some red and white varieties it can exceed the olfactory threshold. In our previous works MeSa have been found in relevant content, both in bound and free form, in some genetically related Italian varieties such as Trebbiano di Lugana, Trebbiano di Soave (both employed in the production of Lugana wines), and Verdicchio. In this research a straightforward filter-and-shot LC-MS/MS method was used for the determination of 7 different MeSa glycosides in 246 samples representative of 18 different monovarietal Italian white wines. Thanks to the minimized sample preparation procedure (wines were only filtered at 0.45 µm) this method allowed a reliable quantification of the analytes without wasting time, energy, and solvents, in total agreement with the Green Analytical Chemistry principles. Analysis were performed using an AB Sciex QTrap 6500+ both in positive and negative mode, equipped with a Waters Acquity C18 HSS-T3 150 mm x 2.1 mm x 1.8 µm column working at 0.28 mL*min-1. Glycosides of interest were MeSa 2-O-β-D-glucoside, MeSa 2-O-α-L-arabinopyranosyl(1à6)-β-D glucopyranoside, MeSa 2-O-β-D-xylopyranosyl(1à6)-β-D-glucopyranoside, MeSa 2-O-β-D-apiofuranosyl(1à6)-β-D-glucopyranoside, MeSa 2-O-α-L-rhamnopyranosyl(1à6)-β-D-glucopyranoside, MeSa 2-O-β-D-glucopyranosyl(1à6)-β-D-glucopyranoside, and MeSa 2-O-β-D-xylnopyranosyl(1à2)[O-β-D-xylopyranosyl(1à6)]-O-β-D-glucopyranoside. MeSa glycosides were found in Verdicchio and Lugana wines, in accordance with literature2,3, whereas where found for the first time in Garganega and Erbaluce varieties. The knowledge of the concentration of MeSa glycosides could be considered a potential predictor of the potential balsamic evolution of white wines. Further details are currently under investigation. Acknowledgments: MIUR project PRIN n. 2017RXFFRR.

References

¹ Poitou, Xavier, Pascaline Redon, Alexandre Pons, Emilie Bruez, Laurent Delière, Axel Marchal, Céline Cholet, Laurence Geny-Denis, and Philippe Darriet. 2021. “Methyl Salicylate, a Grape and Wine Chemical Marker and Sensory Contributor in Wines Elaborated from Grapes Affected or Not by Cryptogamic Diseases.” Food Chemistry 360 (October): 130120. https://doi.org/10.1016/j.foodchem.2021.130120.
² Carlin, Silvia, Domenico Masuero, Graziano Guella, Urska Vrhovsek, and Fulvio Mattivi. 2019. “Methyl Salicylate Glycosides in Some Italian Varietal Wines.” Molecules 24 (18): 3260. https://doi.org/10.3390/molecules24183260.
³ Slaghenaufi, Davide, Giovanni Luzzini, Jessica Samaniego Solis, Filippo Forte, and Maurizio Ugliano. 2021. “Two Sides to One Story—Aroma Chemical and Sensory Signature of Lugana and Verdicchio Wines.” Molecules 26 (8): 2127. https://doi.org/10.3390/molecules26082127.