Main routes of oxygen ingress through different closures into wine bottles.

The main routes of oxygen ingress into wine bottles through "technical" cork stoppers (Neutrocork), natural cork stoppers, and synthetic closures (Nomacorc) were investigated. A comparison was made among closures left uncovered (controls), closures with the closure-glass interface covered, and closures completely covered with a polyurethane impermeable varnish. The oxygen ingress into the bottles was measured by a nondestructive colorimetric method.

Anthocyanone A: a quinone methide derivative resulting from malvidin 3-O-glucoside degradation.

A new compound resulting from the oxidative degradation of maldivin 3-O-glucoside under acid conditions was detected in a wine model solution stored under 90 and 25 degrees C. It was isolated by semipreparative HPLC, and its structure was elucidated by UV-vis spectra, mass spectrometry (LC/MS), and NMR spectroscopy (1-D and 2-D). The compound was identified as 8-beta-d-glucopyranosyl-2,4-dihydroxy-6-oxo-cyclohexa-2,4-dienyl acetic acid (anthocyanone A), which results from nucleophilic attack of hydrogen peroxide to maldivin 3-O-glucoside through a Baeyer-Villiger oxidation followed by other oxidations steps.

Extraction, detection, and quantification of flavano-ellagitannins and ethylvescalagin in a Bordeaux red wine aged in oak barrels.

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

Impact of storage position on oxygen ingress through different closures into wine bottles.

Wine bottle aging is extremely dependent on the oxygen barrier properties of closures. Kinetics of oxygen ingress through different closures into bottles was measured by a nondestructive colorimetric method from 0.25 to 2.

Effect of Armagnac fractions on human platelet aggregation in vitro and on rat arteriovenous shunt thrombosis in vivo probably not related only to polyphenols.

Unlabelled: Previous studies showed that alcohol-free extracts of Armagnac, an oak cask aged spirit rich in polyphenols, inhibit human platelet function in vitro and in vivo, in an experimental rat arteriovenous shunt thrombosis model and in human healthy volunteers. To identify active compounds, we fractionated a freeze-dried extract of a 10-year-old Armagnac using successively chloroform, diethyl ether and ethyl acetate. The 4 resulting fractions were tested on in vitro human platelet aggregation induced by ADP and in vivo on arteriovenous shunt thrombosis after 10 days oral treatment in rats.

(+)-Catechin-aldehyde condensations: competition between acetaldehyde and glyoxylic acid.

(+)-Catechin reaction with two aldehydes (acetaldehyde and glyoxylic acid) was studied in winelike model solution. The two aldehydes were reacted either individually or together with (+)-catechin and in molar excess. The reactions were followed by HLPC-UV and HPLC-ESI/MS to monitor (+)-catechin disappearance as well as dimer and polymer appearance.

Nondestructive colorimetric method to determine the oxygen diffusion rate through closures used in winemaking.

Oxygen is one of the most important factors determining the aging potential of bottled wine, and oxygen diffusion into bottled wine is extremely dependent on the sealing effectiveness of the closure. A nondestructive colorimetric method was developed to measure oxygen diffusion from 1 to 9.8 mg/L during the postbottling period.

The chemistry of wine polyphenolic C-glycosidic ellagitannins targeting human topoisomerase II.

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

Composition and cellular localization of tannins in grape seeds during maturation.

Cell walls were isolated from seeds of grape berries (Vitis vinifera L.), and proanthocyanidin composition was determined over the course of ripening for different levels of vine water status. During the ripening period the tannins from the cell walls were always more polymerized than those from the inner part of the cell.