Total extract (dry extract) is understood to be all substances which occur dissolved in the wine and which remain after distillation (evaporation) of the aqueous-alcoholic portion. The total of all minerals and trace elements is called ash, the quantity of all acids is called total acid and the quantity of all sugars is called residual sugar. By means of metabolomics (a new analytical method at the molecular level) about 7,000 different substances have been identified in wine. However, not only the ingredients present in a wine, but also the quality and origin as well as any manipulation or adulteration of the wine can be determined. The calculation is done in grams per litre (g/l) with an accuracy of 10-1. By far the largest part is still unknown. The approximately 50 most frequent ones, together with their interaction, make up the composition or the very special quality of a wine.
For the total extract content of a wine, the most important factors are the amount of precipitation or climatic conditions during the growing season (since all substances are water-soluble), the root system of the vine (the older the vine, the more extensive the root system) and the soil type with its nutrients. The lower the yield, i.e. the fewer grapes a vine bears, the higher the total extract. The timing of the grape harvest also plays an important role. As a rule, the later the harvest, the higher the values. However, it is not only the must weight alone that is decisive, but the grapes should have the best possible physiological ripeness.
Especially the manifold aromatic substances characterize the aroma or bouquet of a wine and can be clearly identified and named by a professional taster (wine taster) during a wine evaluation. This can also be learned through appropriate practice. Even untrained persons can (could) usually (relatively) easily recognise the aromas of, for example, bitter almond, butter, cassis (black currant or currant), strawberry, cloves, yeast, coffee, cherry, coconut, nutmeg, paprika, pepper, vanilla, lemon and plum. Each grape variety potentially possesses its characteristic, varietal aromas.
The grape must is usually obtained in several pressing operations. The graph shows which parts of the berries and thus relevant constituents of the grapes are affected by the pressing processes (see 11.a First pressing, 10.a Second pressing, 12.a Third pressing). The main component in the wine is water with up to 85%, the rest are substances which influence the smell and taste. These are, in this order, alcohols(ethanol, glycerine, methanol), non-volatile acids(malic acid, lactic acid, tartaric acid and others), residual sugar, flavourings, minerals, phenols(anthocyanins, flavonoids, tannins), proteins, nitrogen compounds and vitamins. In total, the proportion in wine is between 17 and 30 g/l. As a rule, red wine has higher values than white wine, mainly due to the phenols.
In analytical testing as part of quality wine testing, the content of certain ingredients in wine is determined exactly by physical and chemical measuring methods. This is obligatory for the allocation of the official test number (Germany) or state test number (Austria) and minimum quantities are defined for individual substances. The total extract is of essential importance in a qualitative wine evaluation and indicates whether a wine is classified as low in extract(thin, flat, short = up to about 15 g/l) or as rich in extract (full-bodied, full-bodied = from about 22 g/l).
The quantity and the specific composition of all substances gives the structure (framework, body) and determines the aroma, bouquet, colour, shelf life and its ability to develop during bottle ageing - and thus ultimately the quality of the wine. A quality wine should have at least 20 g/l total extract (in the past there was a - now eliminated - legal requirement of at least 18 g/l). The formula again in short form: total extract minus reducing sugar = sugar-free extract minus non-volatile acids = extract residue. The most important ingredients in wine are:
|Water||780 to 850|
|Ethanol (type of alcohol) - 8 g alcohol corresponds to about 1% vol alcohol content||50 to 120|
|Glycerol = Glycerol (type of alcohol)||6 to 25|
|Acids = tartaric, malic, lactic, citric, oxalic, succinic acid etc.||4 to 15|
|Sugar = fructose, glucose, pentoses - see under residual sugar||1 to 50 (250)|
|Minerals and trace elements||1.5 to 4.0|
|Carbon dioxide (for still wine)||0.5 to 1.5|
|Flavouring substances = ester, eugenol, furfural, phenols, vanillin, etc.||0.8 to 1.2|
|Vitamins = mainly B and C||0,4 to 0,7|
|Protein and nitrogen compounds||0.3 to 1.0|
|Methanol (alcohol type)||0.2 to 0.8|
|Colloids (e.g. polymerised phenols)||0,15 to 1,0|
|sulphurous acid = sulphur dioxide (sulphites)||0.15 to 0.25|
|Phenols = anthocyanins, flavonoids, resveratrol, tannins, etc.||0.1 to 2.5|
|Aldehydes (alcohol compounds)||0,01 to 0,1|
|Tartrate - calcium tartrate, potassium hydrogen tartrate||not mandatory|
|Depot - precipitated substances (sediment) - see under polymerization||not compulsory|
During the bottle-ageing or ageing of the wine, the proportion of some substances is reduced because a part is precipitated as a deposit (sediment). The "sugar-free extract" is determined by subtracting from the total extract the reducing sugar and any sucrose present (total sugar content is expressed as invert sugar). However, the sugar-free extract allows only a limited statement for quality assessment. Therefore, the "non-volatile acids" calculated as tartaric acid are subtracted and the "extract residue" is obtained. This determines the "inner quality" of a wine and makes wines best comparable. Very high or very low extract rest values can indicate wine adulteration (Pantschen).
There are defined maximum limits in the finished wine for certain agents used in the winemaking process as part of the cellar work. These are for example ascorbic acid, sulphurous acid and silver chloride. Certain substances in larger quantities indicate defects or, at worst, wine faults. They are formed as a result of unhealthy grape material or poor hygiene and mistakes during vinification. These include acetaldehyde, cadaverine, acetic acid, ethyl carbamate, isoamylamine, histamine, methanol, ochratoxin A, phenylethylamine, putrescine and tyramine. Above a certain amount they have a toxic or harmful effect on health and are therefore defined with maximum permissible quantities in the wine; see ADI (Acceptable Daily Intake).
All aids, work and measures in the vineyard during the vegetation cycle can be found under vineyard care. Complete lists of the numerous cellar techniques, as well as the wine, sparkling wine and distillate types regulated by wine law are included under vinification. Comprehensive information on wine law can be found under wine law.