Non-targeted glycosidic profiling of international wines using Neutral Loss-high resolution mass approach

Many metabolites naturally occur as glycosides or sugar esters, depending on the precursor’s chemical structure. In wine they have traditionally attracted attention due to their organoleptic properties and because they affect the color and aroma of wines. A new approach directed at detailed description of glycosides in a large selection of monovarietal wines (Pinot Blanc, Muller Thurgau, Riesling, Traminer, Merlot, Pinot Noir and Cabernet Sauvignon) was developed by combining high performance liquid chromatography with high resolution tandem mass spectrometry, using a Full MS/AIF/NL dd-MS2 experiment. Over 280 glycoside-like compounds were detected, of which 133 (including low-molecular weight phenols, flavonoids and monoterpenols) were tentatively identified in the form of pentose, deoxyhexose, hexose, hexose-pentose, hexose-deoxyhexose, dihexose and hexose ester derivatives. It was not possible to univocally define the corresponding chemical structure for the remaining 149 glycosides. Non-parametric statistical analysis showed it was possible to well characterise the glycosylated profile of all red and Traminer wines, while the identified glycosides were almost entirely lacking in Pinot Blanc, Riesling and Muller Thurgau wines. Also Tukey’s Honestly Significant Difference test (p<0.05) and Principal Component Analysis confirmed that it was possible to almost entirely distinguish the selected red wines from each other according to their glycosylated profile