Fluorescence Fingerprinting of Bottled White Wines Can Reveal Memories Related to Sulfur Dioxide Treatments of the Must

Abstract

For the first time, Excitation Emission Matrix (EEM) fluorescence spectroscopy was combined with parallel factor statistical analysis (PARAFAC) and applied to a set of 320 dry white wines of the Chardonnay grape variety. A four component PARAFAC model (C1, C2, C3 and C4) best explained the variability of fluorescence signatures of white wines. Subtle changes were observed in EEMs of white wines from two different vintages (2006 and 2007), where different concentrations of sulfur dioxide (0, 4, and 8 g·hL(-1)) were added to the grape must at pressing. PARAFAC results clearly indicated that sulfur dioxide added to the must subsequently influenced white wine chemistry into three distinct sulfur dioxide dose-dependent aging mechanisms. For both vintages, C1 and C2 were the dominant components affected by sulfur dioxide and likely reacting with phenolic compounds associated with some presumably proteinaceous material. Distinct component combinations revealed either SO2 dependent or vintage-dependent signatures, thus, showing the extent of the complex versatile significance underlying such fluorescence spectra, even after several years of bottle aging.

Chemical Transfers Occurring Through Oenococcus oeni Biofilm in Different Enological Conditions

“…These 3D-map representations are illustrated in Figure 2A after 73 days of fermentation and enable describing wine fluorophore composition. This robust and reliable methodology presents the advantage of discriminating winemaking practices like sulfite addition to must (30). In this study, it was applied across wine elaboration in the different conditions, with the objectives of (i) distinguishing the enological conditions, and (ii) evaluating the impact of bacterial biofilm on wine fluorophore composition.…”

“…We routinely monitored wine fermentation by acquiring the Excitation-Emission Matrix of Fluorescence (EEMF) of musts and fresh fermented wines using 3D-fluorescence, with a standardized method described previously (30). All the samples were diluted 40 times with ultrapure water, placed in 1 cm path-length quartz cuvettes and analyzed with an Aqualog unit (Horiba Jobin Yvon, Inc.), by setting the excitation wavelengths from 225 to 600 nm (3 nm interval) and the emission wavelengths from 200 to 600 nm (3.22 nm).…”

Molecular and Macromolecular Changes in Bottle-Aged White Wines Reflect Oxidative Evolution–Impact of Must Clarification and Bottle Closure

“…The area of eluted compounds were measured by the Waters Empower software. The chromatographic methodology was improved from a previous study (Coelho et al, 2015 ). Typical chromatograms are represented in Figure S1 .…”

Multivariate spectroscopy for targeting phenolic choreography in wine with A-TEEMTM and NMR crosscheck non-targeted metabolomics

“…In our study, a five component PARAFAC model (C1-C5) best explained the variability of fluorescence signatures of red wines as a function of pH. The dominant component C4 present a maximum emission signal of 375 nm (emission) and 320 nm (excitation), whereas said emission/excitation profiles present accurate agreements with fluorescence of flavonoid like moieties [11]. C2 and C3 scores present emission/excitation peaks at respectively (375/260), (355/270) nm that most likely are due to .…”

“…1 H-NMR metadata analysis is presented, for fingerprinting some spectral regions associated to phenolics that orthogonally correlates with A-TEEM TM observables. Sample preparation for A-TEEM TM spectroscopy was carried out by dissolving 30 µL of wine samples (3), (6) and (11) with a 200× dilution factor, using a 12% ethanol v/v solution as solvent at three different pH levels: 1, 3, 7. A final volume of 3 mL per sampling was versed in each case within a (1 × 1) cm path length Cuvette Quartz.…”