Untargeted Metabolomics Approach Using UHPLC-HRMS to Unravel the Impact of Fermentation on Color and Phenolic Composition of Rosé Wines.

Color is a major quality trait of rosé wines due to their packaging in clear glass bottles. This color is due to the presence of phenolic pigments extracted from grapes to wines and products of reactions taking place during the wine-making process. This study focuses on changes occurring during the alcoholic fermentation of Syrah, Grenache and Cinsault musts, which were conducted at laboratory (250 mL) and pilot (100 L) scales. The color and phenolic composition of the musts and wines were analyzed using UV-visible spectrophotometry, and metabolomics fingerprints were acquired by ultra-high performance liquid chromatography-high-resolution mass spectrometry. Untargeted metabolomics data highlighted markers of fermentation stage (must or wine) and markers related to the grape variety (e.g., anthocyanins in Syrah, hydroxycinnamates and tryptophan derivatives in Grenache, norisoprenoids released during fermentation in Cinsault). Cinsault wines contained higher molecular weight compounds possibly resulting from the oxidation of phenolics, which may contribute to their high absorbance values.

Multi-method study of the impact of fermentation on the polyphenol composition and color of Grenache, Cinsault, and Syrah rosé wines.

Rosé wines show large color diversity, due to different phenolic pigment compositions. However, the mechanisms responsible for such diversity are poorly understood. The present work aimed at investigating the impact of fermentation on the color and composition of rosé wines made from Grenache, Cinsault, and Syrah grapes. Targeted MS analysis showed large varietal differences in must and wine compositions, with higher concentrations of anthocyanins and flavanols in Syrah. UV-visible spectrophotometry and size exclusion chromatography data indicated that Grenache and Cinsault musts contained oligomeric pigments derived from hydroxycinnamic acids and flavanols which were mostly lost during fermentation due to adsorption on lees. Syrah must color was mainly due to anthocyanins which were partly converted to derived pigments through reactions with yeast metabolites with limited color drop during fermentation. This work highlighted the impact of must composition, reflecting varietal characteristics, on changes occurring during fermentation and consequently wine color.

Elucidating the Color of Rosé Wines Using Polyphenol-Targeted Metabolomics.

The color of rosé wines is extremely diverse and a key element in their marketing. It is due to the presence of anthocyanins and of additional pigments derived from them and from other wine constituents. To explore the pigment composition and determine its links with color, 268 commercial rosé wines were analysed. The concentration of 125 polyphenolic compounds was determined by a targeted metabolomics approach using ultra high-performance liquid chromatography coupled to triple quadrupole mass spectrometry (UHPLC-QqQ-MS) analysis in the Multiple Reaction Monitoring (MRM) mode and the color characterised by spectrophotometry and CieLab parameters. Chemometrics analysis of the composition and color data showed that although color intensity is primarily determined by polyphenol extraction (especially anthocyanins and flavanols) from the grapes, different color styles correspond to different pigment compositions. The salmon shade of light rosé wines is mostly due to pyranoanthocyanin pigments, resulting from reactions of anthocyanins with phenolic acids and pyruvic acid, a yeast metabolite. Redness of intermediate color wines is related to anthocyanins and carboxypoyranoanthocyanins and that of dark rosé wines to products of anthocyanin reactions with flavanols while yellowness of these wines is associated to oxidation.

Separation and isolation of major polyphenols from maritime pine (Pinus pinaster) knots by two-step centrifugal partition chromatography monitored by LC-MS and NMR spectroscopy.

Pine knots are a rich source of lignans, flavonoids, and stilbenes. These bioactive compounds are widely known for their roles to combat human disorders but also to protect plants against pathogens. In order to gain knowledge inside their potential activities, a suitable isolation and purification of these high-added value compounds is required. To this end, centrifugal partition chromatography, as a rapid and useful methodology of separation, was employed and developed. The coefficient partition values (KD ) of six major compounds in nine biphasic solvent systems were determined to evaluate the most appropriate system. Two-step centrifugal partition chromatography was required to separate lignans using ARIZONA system K (n-heptane/ethyl acetate/methanol/water 1:2:1:2, v:v) and to isolate stilbenes and flavonoids using ARIZONA system P (n-heptane/ethyl acetate/methanol/water 6:5:6:5, v:v). Eight one-compound enriched-fractions were obtained as follows: nortrachelogenin (70.1%), secoisolariciresinol (53.7%), isolariciresinol (61.1%), taxifolin (48.4%), pinocembrin (91.3%), pinobanksin (91.1%), pinosylvin (91.4%), and pinosylvin monomethyl ether (91.1%). Additionally, the centrifugal partition chromatography allowed to unravel the composition of pine knot owing to the several fractions generated. Twenty-two compounds were characterized by liquid chromatography-mass spectrometry and NMR spectroscopy, some of which are described for the first time in literature.

Wood and roots of major grapevine cultivars and rootstocks: A comparative analysis of stilbenes by UHPLC-DAD-MS/MS and NMR.

INTRODUCTION: Grapevine wood and roots are by-products obtained during vineyard management. This plentiful biomass is known to be rich in stilbenes and can be used as a source of high-value compounds as well as active natural extracts. However, the stilbenes in grapevine wood and roots from different cultivars and rootstocks remain to be characterized. OBJECTIVE: The present study investigated the stilbene content of eight major Vitis vinifera cultivars and six different rootstocks. In addition, the distribution of stilbenes was established for each of seven parts into which the plants were sub-divided. METHODOLOGY: For stilbene characterization and quantification purposes, an ultra-high performance liquid chromatography-diode array detector-mass spectrometry (UHPLC-DAD-MS/MS) analysis of different samples was carried out. Moreover, structural data of stilbenes was unambiguously studied by nuclear magnetic resonance (NMR) spectra. RESULTS: Whatever the cultivar/rootstock combination, stilbenes were found to be oligomerized from the aerial part to the root system. Furthermore, stilbene content varied widely depending on the cultivars and rootstocks. For instance, the cultivars Merlot, Tannat and Gamay noir were the richest in stilbenes while the rootstocks Gravesac, Fercal and 3390C contained the highest amounts. CONCLUSION: These findings provide insight into the knowledge that major grapevine cultivars and rootstocks can be used as a potential source of complex stilbenes.