Unit of measurement to represent the relative density or the specific weight of grape, that is the mass (weight) in relation to the volume. This mass, also called extract, consists of the dissolved substances in the grape must. That is mainly sugar (Fructose, glucose), but also acids Minerals phenolic Links, proteins and others (some of these substances can then be found in total extract of the wine again). The specific weight of grape must is always greater than 1.0 (water), the difference results largely from the sugar content, The difference between the weight of a certain volume of a must and the weight of the same volume of water is called the weight ratio. The measurement is carried out with measuring devices such as hydrometer (Senkwaage) pyknometer and refractometer (Refraction).
Different units of measurement are used in the individual countries; the most common are:
Klosterneuburger Mostwaage (KMW)
The procedure was developed by August-Wilhelm Freiherr von Babo (1827-1894) in 1861 am Klosterneuburg Wine Institute based on that of Carl Joseph Napoleon Balling (1805-1868) invented saccharometer. This unit of measurement is mostly in Austria. Hungary. Italy and some Eastern states in use. The KMW balance is calibrated to a temperature of 20 ° C. The exact conversion from KMW to Oechsle = KMW x (4.54 plus 0.022 x KMW); roughly calculated KMW x 5. The conversion formulas of the KMW grades in alcohol content are a rough definition and only relatively accurate between 16 and 21 KMW:
Christian F.'s Oechsle (1774-1852) Process developed in the 1820s or unit of measurement named after him is mainly in Germany. Luxembourg and the Switzerland common. The Oechsle balance is usually calibrated to a temperature of 17.5 ° C. A degree Oechsle (Oe) is defined as the weight increase of 1000 milliliters of must by 1 gram. One liter of must with 50 Oe weighs 1050 grams.
Brix or Brix Balling (Bx)
That of Adolf F. Brix (1798-1870) The method developed in 1870 or the unit of measurement named after it is used mainly in the English-speaking countries. The unit of measurement also used in English-speaking countries Balling is almost identical and is often expressed as "brix balling".
The French chemist Antoine Baume (1728-1804) developed methods and the unit of measurement named after him is mainly in the Mediterranean countries among others in France as in Australia common. This measures the total amount of substances dissolved in the grape must and thus the approximate amount of sugar. The Baumé grades correspond almost exactly to the possible alcohol content.
The relationships between the individual units of measurement are not linear to one another. They can therefore only be converted into each other using very complicated formulas. For this reason, tables are mostly used, which often differ due to non-identical formulas. The table below shows the relationship between the three most important units of measurement, as well as the sugar content and possible alcohol content. As a rule of thumb, fermentation gives 10 grams of sugar to 0.66% vol alcohol. This gives about 1% vol from 16.5 to 18 g of sugar. As a rule, white wines are at the lower and red wine at the upper limit.
|OECHSLE||BRIX||KMW||SUGAR g / l||ALCOHOL g / l||ALCOHOL%|
The must weight can approximate the possible alcohol content in wine with (theoretical) complete fermentation of the sugar. Only approximately because this depends on the composition. Two grape musts with the same weight must not necessarily have the same sugar content. A must with high amounts of acid and minerals has less sugar compared to another must, which contains them in smaller amounts. Trockenbeerenauslese can reach 60 KMW or 300 Oechsle and more. Of course, only a relatively small part of the sugar is fermented in this type of wine.
The Frenchman Victor Pulliat (1827-1896) developed a classification for the classification of the grape varieties according to their Mature timing and set the must weight as a comparison criterion. In Germany and Austria, the must weight is an important quality criterion that is used to classify a wine alone. It is also for awarding the official test number (D) or state test number (Ö) important. In the two countries, however, it is given a little too high importance, because there are also other important criteria (see the country-specific minimum must weight values below Germany and Austria ).
The weight of the must is not very meaningful in the warm wine-growing regions. The reading time is therefore determined there according to the acid values. Because the acidity, the PH value as well as the total extract play an at least equally important role. Today the term physiological maturity the maturation (Ripeness) of the grapes described far more comprehensively. Regarding the different analytical methods for the determination or measurement of the fermented sugar content ( residual sugar ) in wine see under sugar content,