Jaune wines

Charpentier, C., Dos Santos, A. M., and Feuillat, M. (2004). Release of macromolecules by Saccharomyces cerevisiae during aging of flor Sherry wine "vin jaune". Int. ]. Food Microbiol. 96, 253-262. 

The aroma of botrytized wines has been studied more extensively than that of the grapes. Mashuda et ah (1984) identified the lactone sotolon (4,5-dimethyl-3-hydroxy-2,(5)-furanone) as a principal compound in a botrytized aroma. Sotolon is also a key aroma compound in flor wines, for example, vin jaune, sherry (Dubois et ah, 1976 Martin and Etievant, 1991 Moreno et ah, 2005). However, Sponholz and Hiihn (1993) found no correlation between the degree of Botrytis infection and sotolon... 

It has been suggested that the presence of aldehydes and methyl-ketones contribute to the rancio odor of barrel aged Port wine (2) and also in white wines (1). Other volatiles, were also studied in ports (5, 4, 5, 6, 7, 8). More recently, 3-hydroxy-4,5-dimethyl-2(5H)-furanone (Sotolon) has been suggested to be a key odorant in the aroma of aged port (9). This highly odor active molecule has been shown to contribute to the aroma of Jura wines vin jaunes 10, 13, 14, 15), vins doux naturels (14) Tokay wines 11), Botrytised wines (id) and Sherry wines (72). 

Figure 5, Sotoion formation pathway (I) SaM (34) (II) wines vins jaunes (13).

In view of the very small quantities of free ethanal present in still wine, their acetal content is practically zero. Only wines with a high ethanal content have a significant concentration of acetal. Sherry, with an ethanol concentration on the order of 280 mg/1, contains 45-60 mg/1, while the concentration in Vin Jaune from the Jura may be as high as 150 mg/1. 

Sotolon (Volume 1, Section 10.6.4) also results from a condensation reaction, not catalyzed by enzymes, between a-keto butyric acid and ethanal. It is also present in Vin Jaune from the Jura, where it is responsible for the walnut aroma so typical of this wine (Martin et al, 1992). 

The concept of oxidative defects is quite subjective, as there are many wines where an oxidative character (rando) is considered desirable. Wines aged under a yeast bloom are a classic example, e.g. Vm Jaune from the Jura (Volume 1, Section 14.5). The yeast acts as an oxidation-reduction bnffer and prevents excessive oxidation. Vin Jaune is well known for its highly oxidized character and contains large concentrations of free and combined ethanal (Fignre 8.1) (Etievant, 1979). The same is trne of Sherry. 

Pasteur was the first to include flor with bacterial problems, because, like acetic spoilage, it involves a mycodermic microorganism. However, flor is caused by a yeast (which Pasteur called My coderma vini) and not a bacterium (Mycoderma aceti). Flor should not be confused with the bloom formed by Saccharomyces cerevisiae under certain, specific, conditions, responsible for producing high-quality wines such as Sherry and Vin Jaune from the Jura (Volume 1, Section 14.5). 

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