Identification of caffeic acid as a major component of Moscatel wine protein sediment

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…

Limited information is available on grape wall-derived polymeric structure/composition and how this changes during fermentation. Commercial winemaking operations use enzymes that target the polysaccharide-rich polymers of the cell walls of grape tissues to clarify musts and extract pigments during the fermentations. In this study we have assessed changes in polysaccharide composition/ turnover throughout the winemaking process by applying recently developed cell wall profiling approaches to both wine and pomace polysaccharides. The methods included gas chromatography for monosaccharide composition (GC-MS), infra-red (IR) spectroscopy and comprehensive microarray polymer profiling
(CoMPP) using cell wall probes.

Flavonols are a class of flavonoid compounds derived from plant secondary metabolism. There they play different roles like antioxidants, internal regulators and UV screenings. In red wines, flavonols have increasingly received consideration by part of scientific and winemakers according their properties began to arise known. Among these stand out wine colour stabilization and their value as bioactive compounds. In this work the complete series of the acetylated and p-coumaroylated derivatives of the 3-O-glycosides of methoxylated flavonols, namely isorhamnetin, laricitrin and syringetin, have been identified in grapes and their respective wines from Vitis vinifera cv. Tannat.

The economic importance of grapevine as a crop plant makes Vitis vinífera a good model system to study the improvement of the nutraceutical properties of food products (Vezulli et al. 2007). Stilbenes in general, and trans-resveratrol in particular, have been reported to be responsible for various beneficial effects. Resveratrol´s biological properties include antibacteria and antifungal effects, as well as cardioprotective, neuroprotective and anticâncer actions (Guerrero et al. 2010 ). Stilbenes can be induced by biotic and abiotic elicitors since they are phytoalexins (Bavaresco et al. 2001).

In general, there is a well-established lexicon related to wine aroma and taste properties; however mouth-feel-related vocabulary usually includes heterogeneous, multimodal and personalized terms. Gawel et al.
(2000) published a wheel related to mouthfeel properties of red wine. However, its use in scientific publications has been limited. The authors accepted that the approach had certain limitations as it included redundant and terms with hedonic tone and some others were absent. It is of high interest to generate a mouth-feel lexicon and finding the chemical compound or group of compounds responsible for such properties in red wine. In the present work a chemical fractionation method has been developed.