Given its rich history and tradition as well incredible complexity, wine has been the subject of a considerable amount research. Grape phenolics, because their complexity importance in quality, serves good example how science have coevolved. This review summarizes early research on grape phenolics provides justification for continued

Grape variety [Cabernet Sauvignon (CS) and Merlot (M)] effect on the proanthocyanidin composition sensory perception of wine grapes from Bordeaux vineyards for two successive vintages (2006 2007) is reported. The flavan-3-ol monomers [(+)-catechin = C, (−)-epicatechin EC, (−)-epicatechin-O-gallatte ECG] oligomers [dimers B1, B2, B3, B4 trimer Cat-Cat-Epi (T)] in grape seed skin tannin extracts were identified quantified at harvest. Proanthocyanidin subunit compositions, percentage...

This work outlines the results from an investigation to determine effect of oxygen dissolved at bottling and specific barrier properties commercially available closures on composition, color sensory a Bordeaux Sauvignon Blanc wine during two years storage. The importance for development after was also assessed using airtight bottle ampule. Wines were antioxidants (SO(2) ascorbic acid), varietal thiols (4-mercapto-4-methylpentan-2-one, 3-mercaptohexan-1-ol), hydrogen sulfide sotolon content,...

Abstract Polyphenolic nonahydroxyterphenoyl‐containing C ‐glycosidic oak ellagitannins are found in wine as a result of the aging this beverage oak‐made barrels. Once slightly acidic (pH∼3–4), some these complex natural products such (−)‐vescalagin ( 1 ), but not its C‐1 epimer (−)‐castalagin 2 can capture grape‐derived nucleophilic entities ethanol, flavanols catechin 10 ) and epicatechin b anthocyanin oenin 13 thiolic glutathione 16 to furnish condensation with retention configuration at...

The antioxidant synergy between (+)-catechin and other wine or biological antioxidants (Trolox, ascorbate, SO(2), uric acid) was measured in vitro using the Folin-Ciocalteu (FC) metmyoglobin assays. Although two assays are based on very different reagents (i.e., metal salts versus organic biochemical reagents), individual showed similar relative activities both systems. In addition, interaction studies simple additive effects all cases except with (+)-catechin/SO(2) mixture, which a...

The (+)-catechin−acetaldehyde condensation was studied as a model for tannin polymerization and precipitation in red wines. It shown by using LSIMS that reaction products are catechin polymers with CH−CH3 bridges at two sites. Before the end of monomer conversion into there is an aggregation followed phase separation. Particle mean diameter measured dynamic light scattering directly medium. Comparison between particle polymer sizes showed aggregate colloidal intermediates before large degree...

Wine bottle aging is extremely dependent on the oxygen barrier properties of closures. Kinetics ingress through different closures into bottles was measured by a nondestructive colorimetric method from 0.25 to 2.5 mL oxygen. After 12, 24, and 36 months storage, only control (glass ampule) airtight. Other displayed rates, which were clearly influenced closure type independent storage position (upright, laid down) for most tested, at least during first 24 experiment under controlled...

A dimeric polyphenolic fraction was purified from a two months old Cabernet Sauvignon wine. This studied by LC-ES-MS. Several products with 606 mass corresponding to dimer of 2 flavanol monomer units linked an ethyl bridge were detected. Identification catechin-acetaldehyde dimers achieved injection synthetic dimers. In addition retention time, spectra obtained on each peak. By increasing the cone voltage in electrospray source, specific fragments could be generated which further confirm...

In dry white wines, two different forms of instability occur: (i) substantial yellow or yellow-green deposits are observed principally due to flavonol quercetin; and (ii) protein leads casse. Polyvinyl polypyrrolidone (PVPP) is used adsorb phenols from beverages, bentonite eliminate heat instable protein. However, in both cases, their effects still largely unknown. This study uses a multitechnique approach gain better molecular understanding the association polyphenol aglycones with PVPP...

An extraction procedure and an analytical method have been developed to detect quantify for the first time a series of ellagitannin derivatives formed in wine during aging oak barrels. The involves preliminary purification step on XAD7 HP resin followed by second TSK 40 HW gel. resulting extract is analyzed compound identification quantitative determination high-performance liquid chromatography−electrospray ionization−mass spectrometry single ion recording mode. Reference compounds, which...

Condensed tannins are responsible for astringency and bitterness participate in the color stability of red wines. During wine making aging, they undergo chemical changes including, example, acetaldehyde-induced polymerization. Following this study, ethylidene-bridged flavan-3-ols were monitored different vintage wines made from grapes collected same vineyard three wineries Bordeaux, Pauillac, Saint Julien. Flavan-3-ol ethylidene bridges quantified by 2,2'-ethylidenediphloroglucinol (EDP)...

The main routes of oxygen ingress into wine bottles through "technical" cork stoppers (Neutrocork), natural stoppers, and synthetic closures (Nomacorc) were investigated. A comparison was made among left uncovered (controls), with the closure−glass interface covered, completely covered a polyurethane impermeable varnish. measured by nondestructive colorimetric method. Technical essentially to atmospheric during first 24 months storage. Oxygen within corks diffused slowly but continuously...

Abstract Kinetic and thermodynamic UV/Vis structural NMR spectroscopic investigations on the anthocyano‐ellagitannin hybrid 1‐deoxyvescalagin‐(1β→8)‐oenin revealed that its enhanced color stability relative to of red‐colored pigment oenin resulting bathochromism can be rationalized in terms an intramolecular π‐stacking between grape‐derived chromophore oak‐derived vescalagin 4,6‐hexahydroxydiphenoyl moiety. The results led us suggest this bathochromism‐inducing molecular association could...

RATIONALE Stilbenoids are secondary plant metabolites responsible for the protection of multiple species including grape vine from bacterial and fungal infection. Red wine has been shown to be a major source these compounds in human diet, where they display an array health benefits. Providing more complete profile stilbenoids present red wine, this study detects 41 stilbenoid compounds, 23 which have never before detected wine. METHODS extracts were scanned using ultra‐high‐performance...

Skin and seed grape extracts of three red varieties (Merlot, Tannat, Syrah) at different stages ripening were studied for their total phenolic content (TPC) by using the Folin-Ciocalteu assay antioxidant capacity (TAC) spectrophotometric electrochemical assays. Flavanol anthocyanin compositions also investigated Ultra Performance Liquid Chromatography coupled with Mass Spectrometry (UPLC-MS). Results showed that seeds had highest potential compared to skins all ripening. The TPC TAC values...

A rapid method that permits separation of grape seed proanthocyanidins according to their polymerization degrees has been developed. This was based on liquid/liquid extraction and relative solubility these compounds in different solvents (water, ethyle acetate, methanol, chloroform). The fractions obtained were then analyzed by various HPLC techniques (normal phase, reversed phase after thiolysis, gel permeation) determine mean degree (DP) molecular weight profiles. Results show this can be...

Cell walls were isolated from seeds of grape berries (Vitis vinifera L.), and proanthocyanidin composition was determined over the course ripening for different levels vine water status. During period tannins cell always more polymerized than those inner part cell. At maturity this difference becomes significant compared to véraison, due a increase in mean degree polymerization wall tannins. The tannin typical seed quite similar two fractions studied, but epicatechin gallate proportion...

Oxygen is one of the most important factors determining aging potential bottled wine, and oxygen diffusion into wine extremely dependent on sealing effectiveness closure. A nondestructive colorimetric method was developed to measure from 1 9.8 mg/L during postbottling period. This used study through different closures available market. After 365 days horizontal storage, only control bottle impermeable atmospheric oxygen; all other exhibited variable rates diffusion, which were much greater...

For two successive years, cell walls were isolated from the internal part of skin cells Vitis vinifera L. cv. Cabernet Sauvignon grape berries grown in a vineyard. Procyanidin localization and composition determined over course development. Tannins mainly localized inner fraction, due to their biosynthesis storage. Cell wall tannins always exhibited higher mean degree polymerization as compared which had constant mDP. The mDP also tended increase at end maturation. Our results suggest tannin...