Simplified, those substances which remain after the evaporation of a wine represent the extract.

One litre of wine consists primarily of approx. 800-900 g water, 50-100 g ethyl alcohol, 20-30 g glucose/fructose (sugar), 5-10 g glycerine and approx. 6-12 g various acids.

After evaporation, an inconspicuous-looking, small residue remains, which consists of sugar, non-volatile acids, tannin, minerals, vitamins, pigments and various nitrogen compounds. Often certain higher alcohols are also included. Likewise, sugar is sometimes subtracted in the analysis (sugarless/sugar-free extract).

Red wines generally have more extract than white wines. This 'little residue' has been taken very seriously for centuries, as it also has a decisive influence on the taste of a wine.

The reason for this is that the contribution of several components of the extract has an enormously relevant effect on the impression conveyed of the 'body' of a wine. 'Low in extract', for example, sometimes contributes to the (negative) label 'thin' among connoisseurs. A good winemaker will thus strive to naturally co-determine the extract to ensure the optimal development of the 'body' of his wine variety.

Minimal enrichments of the quantities of certain parts of the extract can cause fantastic advantages or also devastating disadvantages. Many a high-spirited winemaker in California, for instance, who enthusiastically tried to age their wines in traditional oak barrels in order to enrich their wines with the fantastic aromas, had to realize to their horror that these barriques can also enrich a wine excessively with biting tannin. 'Lots of extract' is therefore not always synonymous with 'lots of quality'.