The hidden face of wine polyphenol polymerization highlighted by high resolution mass spectrometry

Polyphenols, including tannins and red anthocyanin pigments, are responsible for the color, taste, and beneficial health properties of plant-derived foods and beverages, especially in red wines. Known compounds represent only the emerged part of the "wine polyphenol iceberg". It is believed that the immersed part results from complex cascades of reactions involving grape polyphenols and yeast metabolites. We used a nontargeted strategy based on high-resolution mass spectrometry and Kendrick mass defect plots to explore this hypothesis. Reactions of acetaldehyde, epicatechin, and malvidin-3-O-glucoside, representing yeast metabolites, tannins, and anthocyanins, respectively, were selected for a proof-of-concept experiment. A series of compounds including expected and so-farunknown structures were detected. Random polymerization involving both the original substrates and intermediate products resulting from cascade reactions was demonstrated

Linking cocoa polyphenol composition to chocolate quality with Average-Mass-Spectra fingerprints

Linking cocoa polyphenol composition to chocolate quality with Average-Mass-Spectra fingerprints. CoCoTea 2019 (5. International Congress on Cocoa Coffee and Tea

Influence of sample and mobile phase pH on HPLC-DAD-MS analysis of anthocyanins and other phenolic compounds in wine

In this study, the influence of pH of the wine sample (pH 1.2 and 3.3) and of the HPLC mobile phase (1 and 2 % formic acid in the solvent) on anthocyanin and phenolic acid analysis was explored. Wine samples acidified at pH 1.2 were analyzed immediately, after 30 min, 2h and 3.5h, in order to check if any degradation of phenolic compounds occurred during the storage. Maximum response of the flavylium cation of peonidin-3-glucoside (at 520 nm), statistically significant (p 0.05), meaning that both 1% and 2% formic acid in the mobile phase are suitable for anthocyanin analysis. Regarding phenolic acids, lower peak intensities, statistically significant (p < 0.001), were obtained in the negative ion mode with 2 % formic acid in the mobile phase, presumably due to the lower proportion of acids in the anionic form under more acidic conditions. Thus, 1% formic acid in the mobile phase and acidification of the sample at pH £ 1.2 were selected as the best compromise for simultaneous analysis of anthocyanins and phenolic acids. Acidification of the wine samples at pH 1.2 followed by a 30 min delay enabled total transformation of chalcone and carbinol forms into the corresponding flavylium cations, without causing degradation of the other wine phenolics. The optimized conditions were applied for MS identification of 69 compounds from different phenolic groups present in Vranec wine

Influence of maceration time, SO2 and yeast strain on the content of phenolic compounds in wines from Vranec and Merlot varieties

Red wines from V. vinifera Vranec and Merlot grapes produced using a series of identical fermentation conditions for all wines (maceration times of 3, 6 and 10 days, two doses of sulphur dioxide, 30 and 70 mg/L SO2, and two yeasts for fermentation, Macedonian yeast-Vinalco and French yeast-Levuline) were subject of investigation. The concentration of phenolic acids, anthocyanins and flavan-3-ol monomers was determined by reversed-phase HPLC, while analysis of proanthocyanidins was performed by HPLC after acid-catalysed cleavage in the presence of phloroglucinol. Vranec wines were richer in anthocyanins and hydroxycinnamic acids and showed higher content of condensed tannins in comparison to the Merlot wines obtained under the same technological conditions. Vranec wines reached highest concentrations of anthocyanins after 6 days of maceration, while gradual increase of proanthocyanidins was observed both for Vranec and Merlot wines with increased pomace contact. The highest contents in acylated anthocyanins and proanthocyanidins were found in Vranec wines fermented with French yeast, macerated for 10 days. Differences in the extraction kinetics between the two yeast strains can probably be attributed to differences in their fermentation kinetics. Higher doses of SO2 resulted in increased extraction of all phenolic compounds. Statistical treatments of the data, using cluster analysis and principal component analysis, showed a clear separation of the samples, mainly according to the variety, followed by sub-grouping related to the maceration time and SO2 content

HPLC analysis of hydroxycinnamic acid derivatives in Smederevka and Chardonnay wines

A reversed phase liquid chromatographic method for identification and quantification of hydroxycinnamic acid derivatives was used to analyze their content in Macedonian white wines, Smederevka and Chardonnay (Vitis vinifera L.) produced under different vinifications. Winemaking procedures for both varieties included addition of two doses of SO2 (50 and 100 mg/L) and two yeasts for fermentation (Vinalco and Levuline). Separation of the components by direct injection into HPLC was performed using reversed-phase Atlantis dC18 column, monitored at 320 nm, and the mobile phase consisted of water/formic acid (99:1; solvent A), and acetonitrile/water/formic acid (80:19:1; solvent B). The main phenolic acids present in the wines were caftaric acid (caffeoyltartaric acid) and coutaric acid (coumaroyltartaric acid). In addition, HPLC-MS analysis was carried out to confirm the identity of the separated compounds, recording the spectra in negative ion mode. In general, differences in their contents in Smederevka and Chardonnay wines were observed. Thus, Chardonnay wines were richer in phenolic acids compared to Smederevka wines. The dominant component in Chardonnay wines was trans-caftaric acid, while, trans-coutaric dominated in Smederevka wines. Regarding the influence of SO2, it was observed that wines with higher dose of SO2 contained higher levels of acids, since SO2 suppress the activity of oxidases, preventing oxidation of these readily oxidizable phenols and wine browning. The influence of the yeast on the content of phenolic acid derivatives was not significant. Principal component analysis was performed in order to check if the studied wines can be distinguished, showing separation of the samples according to the variety and SO2 doses