Trans-resveratrol concentrations in wines Cabernet Sauvignon from Chile

Polyphenols are present in a wide variety of plants and foods such as tea, cacao and grape1. An important sub-class of these compounds is the flavanols present in grapes and wines as monomers (e.g (+)-catechin or (-)-epicatechin), or polymers also called condensed tannins or proanthocyanidins. They have important antioxidant properties2 but their biosynthesis remains partly unknown. Some recent studies have focused on the role of glycosylated intermediates that are involved in the transport of the monomers and may serve as precursors in the polymerization mechanism3, 4. The global objective of this work is to identify flavanol glycosides in grapes or wines, describe their structure and determine their abundance during grape development and in wine.

For characterization, sensory designing and authentication rapid analytical technologies have become available. Some, like Proton Transfer Reaction Mass Spectrometry allow a rapid spectrum of the volatile compounds of wines. Combined with chemometrics wines can be characterized. The same approach can be used to calculate the results of virtual mixtures and allow formulation of constant quality blends. Other new techniques and portable devices based on spectroscopy allow measurements on production sites and in grocery stores, even for the smart consumer. We will present some examples of the application of these techniques for authentication of wines, both in the laboratory and on site.

Beihong and Beimei are two wine cultivars from ‘Muscat Hamberg’ (V. vinifera L.) and wild V. amurensis Rupr., which were released in China in 2008. Here，two enology practices were reported. Firstly, the impact of different yeasts including D254, GRE, K1, D21 and BDX on dry wine quality of Beihong and Beimei was investigated. For Beihong, among wines fermented by all yeasts, residual sugar content was the lowest, total anthocyanin and resveratrol contents were the highest in the wine by D254. However, the wine by D254 had lower titrable acid than those by the other yeasts except BDX.

Grapevine berries produce thousands of secondary metabolites of diverse chemical nature that have been largely detailed in the past due to their importance for defining wine quality. The wide Vitis vinifera diversity, resulting in thousands of different varieties well detailed in many studies regarding berries, is still not investigated in vegetative organs, leaves in particular. Deepening knowledge related to this aspect could be of great interest for many reasons (for example the possibility of using leaf extract for pharmaceutical, cosmetic and nutrition purposes) but, above all, for understanding the susceptibility of different grapevine varieties to pathogens.

País grape has been estimated to arrive to Chile almost 500 years ago, being the first strain grown in this country. Traditionally, this grape has been used to mix with other varieties, to produce poor quality wines, but today is beginning to be used in the production of high quality wines. However, very little is known about the chemical characteristics of this variety. The aroma is one of the most important quality attributes of wine. Volatile compounds of this beverage may come from the grape (varietal aromas), from the fermentation process, from the ageing. The aromatic compounds are found in the grape in two forms: as free volatile compounds and as non-volatile compounds. The last ones, are aroma precursors present mainly as glycoconjugates formed by a sugar and an aglycone…