Polyvinylpolypyrrolidone (PVPP) is a fining agent polymer used in winemaking to adjust rosé wine color and to prevent organoleptic degradations by reducing polyphenol content. The impact of this polymer on color parameters and polyphenols of rosé wines was investigated, and the binding specificity of polyphenols toward PVPP was determined. Color measured by colorimetry decreased after treatment, thus confirming the adsorption of anthocyanins and other pigments. Phenolic composition was determined before and after fining by targeted polyphenomics (Ultra Performance Liquid Chromatography (UPLC)-Electrospray Ionization(ESI)-Mass Spectrometry (MS/MS)). MS analysis showed adsorption differences among polyphenol families. Flavonols (42%) and flavanols (64%) were the most affected. Anthocyanins were not strongly adsorbed on average (12%), but a specific adsorption of coumaroylated anthocyanins was observed (37%). Intermolecular interactions were also studied using molecular dynamics simulations. Relative adsorptions of flavanols were correlated with the calculated interaction energies. The specific affinity of coumaroylated anthocyanins toward PVPP was also well explained by the molecular modeling.
A rapid Ultra performance Liquid chromatography coupled with Quadrupole/time of flight Mass Spectrometry (UpLc-Qtof-MS) method was designed to quickly acquire high-resolution mass spectra metabolomics fingerprints for rosé wines. An original statistical analysis involving ion ratios, discriminant analysis, and genetic algorithm (GA) was then applied to study the discrimination of rosé wines according to their origins. After noise reduction and ion peak alignments on the mass spectra, about 14 000 different signals were detected. The use of an in-house mass spectrometry database allowed us to assign 72 molecules. Then, a genetic algorithm was applied on two series of samples (learning and validation sets), each composed of 30 commercial wines from three different wine producing regions of France. Excellent results were obtained with only four diagnostic peaks and two ion ratios. This new approach could be applied to other aspects of wine production but also to other metabolomics studies. Scientific RepoRtS |(2020) 10:1170 | https://doi.www.nature.com/scientificreports www.nature.com/scientificreports/ spectrometry and ion ratio fingerprints will be very useful in the future in other fields of metabolomics and sample discrimination. Materials and MethodsChemicals. All chemicals were of analytical reagent grade. Acetonitrile and formic acid were purchased from Biosolve Chemicals.Deionized water was obtained from a Direct-Q3 purification system (Millipore).Wines and sample preparation. A total of 60 commercial rosé wines were purchased from large retailers.They were selected for their geographic origins (3 different regions of France: Bordeaux, Languedoc, Provence, 20 samples per region), and color range. Wines were from several grape varieties, with unknown wine making processes and from different vintages ranging from 2010 to 2015. Just after bottle opening, samples of 1.5 mL were prepared and kept in closed plastic Eppendorf at −80 °C. Before analyses, samples were brought to room temperature, centrifuged, and injected in triplicates in a randomized order. UPLC-ESI-Tof parameters.Analyses were performed with a Waters Acquity H-Class UPLC system connected to a HD-MS Synapt G2-S mass spectrometer equipped with a Z-Spray source (electrospray ionization ESI). The UPLC system included a vacuum degasser, a quaternary pump (QSM), a cooled autosampler maintained at 10 °C (SM-FTN), and a thermostated column compartment. MassLynx software (version V4.1) was used for instrument control and data processing.The column used for chromatographic separation was a PLRP-S reversed phase (4000 Å, 50 × 2.1 mm, 5 µm, Agilent Technologies) maintained at 25 °C. The binary mobile phase consisted of Milli-Q water (solvent A) and acetonitrile (solvent B) both acidified with 1% formic acid. The separation was performed at a constant flow rate of 0.6 mL/min, using the following short gradient: 1% B for 1 min; 1-100% B in 0.5 min; 100% B for 0.5 min; 100-1% B in 1.5 min; and reequilibration at 1% B for 2.5 min. The injection volume was 10 µL.R...
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