Relationship between the Sensory-Determined Astringency and the Flavanolic Composition of Red Wines

[EN] The relationship between the proanthocyanidin profile and the perceived astringency was assessed in 13 commercial Tempranillo red wines. The concentration and compositional information were obtained by liquid chromatography with diode array detection coupled to electrospray ionization mass spectrometry after acid-catalyzed depolymerization of wine proanthocyanidins in the presence of excess phloroglucinol. Statistical analysis of the results showed significant correlations between sensory and chemical determinations. Astringency was more affected by the subunit composition than by the total concentration or the average degree of polymerization of wine proanthocyanidins. Higher proportions of epicatechin (EC) subunits in extension positions and gallocatechin (GC) subunits in terminal positions were shown to increase astringency. On the contrary, the amount of epigallocatechin (EGC) in both extension and terminal positions was negatively correlated with the perceived astringency

Phenolic Compositions of 50 and 30 Year Sequences of Australian Red Wines: The Impact of Wine Age

The phenolic composition of red wine impacts upon the color and mouthfeel and thus quality of the wine. Both of these characteristics differ depending on the age of a wine, with the purple of young wines changing to brick red and the puckering or aggressive astringency softening in older wines. This study investigated the color parameters, tannin concentrations and tannin composition of a 50 year series of Cabernet Sauvignon wines from a commercial label as well as 30 year series of Cabernet Sauvignon and Shiraz wines from a separate commercial label to assess the impact of wine age on phenolic composition and concentration. The wine color density in wines of 40 to 50 years old was around 5 AU compared with 16 AU of wine less than 12 months old, which correlated well with the concentration of non-bleachable pigments and pigmented polymers. Conversely, the anthocyanin concentrations in 10 year old wines were substantially lower than that of recently bottled wines (around 100 mg/L compared with 627 mg/L, respectively), adding further evidence that non-bleachable pigments including pigmented polymers play a much larger role in long-term wine color than anthocyanins. No age-related trend was observed for tannin concentration, indicating that the widely noted softer astringency of older red wines cannot necessarily be directly related to lower concentrations of soluble wine tannin and is potentially a consequence of changes in tannin structure. Wine tannins from older wines were generally larger than tannins from younger wines and showed structural changes consistent with oxidation.Jacqui M. McRae, Robert G. Dambergs, Stella Kassara, Mango Parker, David W. Jeffery, Markus J. Herderich and Paul A. Smit

Methyl jasmonate: effect on proanthocyanidin content in Monastrell and Tempranillo grapes and wines

Proanthocyanidins or “condensed tannins” play an important role in the organoleptic properties of wines, and their levels in both grapes and wines can be achieved by several means. One such way is based on the use of elicitors, agrochemicals which were originally designed to improve resistance to plant pathogens, but whose action mechanism has also been found to increase polyphenol levels. Among these chemical elicitors, jasmonic acid and, especially, its methyl ester, methyl jasmonate (MeJ), can increase the production of secondary metabolites such as anthocyanins, flavonoids, phenolic acids, and other antioxidant molecules, enhancing the fruit quality and post-harvest life, as well as increasing their health-related properties. The objective of this study was to determine whether the application during two consecutive years of MeJ to Monastrell and Tempranillo varieties at the veraison period had any effect on the accumulation of proanthocyanidins and subsequently on their extractability into wine. The results obtained indicated that treatments increased the grape proanthocyanidin content only in one of the years but for both varieties tested, as well as their levels in the corresponding wines.This work was made possible by financial assistance from the Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria. RTA2013-00053-C03-02 and RTA2013-00053-C03-01. J. P. and T. G.-C. also wish to thank the INIA-Gobierno de La Rioja and European Social Fundfor their contracts. T. G.-C. also thanks MINECO for funding her Ramón y Cajal contract.Peer reviewe