Varietal aroma

1 The general concept of varietal aroma 12 Terpene componnds 

7 Development of grape aromas during ripening and the impact of vineyard factors 

Wine aromas are made up of several hundreds of volatile compounds, at concentrations ranging from several mg/1 to a few ng/1, or even less. The olfactory perception thresholds of these compounds also vary quite considerably. Consequently, the olfactory impact of the volatile compounds in wine depends both on concentration and type. Certain compounds, present in trace amounts, on the order of ng/1, may play a major role in aroma, whereas other, much more plentiful, compounds may make only a slight contribution. Furthermore, the impact of each component on the 

The concept of thresholds , always applied in a given medium (water, dilute alcohol solution, white wine or red wine), is used to indicate the characteristics of various aromatic substances  

Perception threshold. This is the minimum concentration at which the presence of an odoriferous substance is detected by 50% of tasters in a triangular test, although they are not necessarily capable of identifying the smell. 

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B) Without normally distinguishable varietal aromas California (etc) dry red table wine (burgundy, claret, chianti), Carignane, Charbono, Cinsaut, Malvoisie, Mourastel, Valdepenas. 

Sweet. California (etc) red table and sweet red table, proprietary types generally without specific fmit or varietal aroma unless Concord-type or fmit wines (blackberry, raspberry, strawberry, etc)... 

White wines not containing anthocyanin (red) pigments d) With (usually) distinguishable varietal aromas... 

Some of the early descriptions of the effect of MOX on red wine included an interesting cycling effect where certain organoleptic aspects of wine quality appear to get worse before the continued application of MOX leads to the desired improvements (Dykes and Kilmartin, 2007 Parish et al., 2000 Vinovation, 2009). In the first "structuring" phase (for several days to weeks), the wine tannins are said to become more aggressive and the varietal aromas decrease, after which the tannins soften and... 

Table 11.1 Odour-active compounds involved in varietal aroma of wine ...

Recent studies have focused on cysteine-S-conjugates as varietal aroma precursors (see Baumes, 2009). Chemically, these odorless compounds are S-substituted derivatives of L-cysteine, differing in the attached to sulfur atom. During fermentation, extremely odorous volatile thiols are formed from these precursors (see Dubourdieu and Tominaga, 2009). One of these thiols, 3-sulfanylhexan-l-ol (3SH), is known as an important aroma... 

Monoterpenoids have been described as being responsible for the varietal aroma of some wines. The characteristic composition of this chemical class in several grape varieties is claimed to be only marginally influenced by the growing area while other find effect of light exposure. These compounds are responsible for the aroma profile of the Muscat... 

Fermentation of the base white wine, used in producing the fortifying brandy, follows standard procedures. In Cognac, nonaromatic varieties, such as Trebbiano and Baco 22A, are used, where in Armagnac, Trebbiano is preferred. These cultivars have little varietal aroma, retain high acidity, and have limited alcohol production potential. In California, French Colombard, Thompson Seedless, and Tokay are the cultivars without distinctive flavor used to produce a brandy base wine. 

By careful processing, the winemaker brings the wine to a finished state. The white and rose wines will have maintained their bouquet and aroma and flavors. The red table wines will have been softened by careful fining with such agents as gelatin and PVPP, will be fruity, and will have distinctive varietal aromas and flavors with minimal astringency. 

Loscos, N., Hemandez-Orte, R, Cacho, J., Ferreira, V. (2007) Release and Formation of Varietal Aroma Compounds during Alcoholic Fermentation from Nonfloral Grape Odorless Flavor Precursors Fractions. J. Agric. Food Chem., 55, 6674-6684. 

Therefore, volatile phenols play a minor role in the aroma of most wines, and when their influence is significant in certain wines, they have mostly a negative effect, which can definitely depreciate their aroma in limit cases (phenolic off-flavors). Thus, the corresponding precursors in grape, phenolic acids, as well as the above-mentioned unsaturated lipids, are hardly taken into account to capture an essential characteristic of the varietal aroma, but to avoid their transformation into off-flavors. 

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