Unit of measurement for representing the relative density or the specific gravity of grape, that is the mass (weight) in relation to the volume. This mass, also referred to as extract, consists of the solutes in the grape must. That's mainly sugar (Fructose, glucose), as well acids, Minerals, phenolic Links, proteins and others (these substances are then found partly in the total extract the wine again). The specific gravity of grape must is always greater than 1.0 (water), the difference is largely due to the sugar content, The difference "weight of a certain volume of a must" to "weight of the same volume of water" is called weight ratio. The measurement is carried out with measuring equipment such as hydrometer (Senkwaage) pyknometer and refractometer (Refraction).
Different units of measure are in use in the individual countries; the most common ones are:
Klosterneuburger Mostwaage (KMW)
The procedure was by August-Wilhelm Freiherr of Babo (1827-1894) in 1861 on Klosterneuburger Weinbauinstitut based on the by Carl Joseph Napoleon Balling (1805-1868) invented saccharometer. This unit of measurement is mainly in Austria. Hungary. Italy and some eastern states in use. The KMW balance is calibrated to a temperature of 20 ° C. The exact conversion of KMW to Oechsle = KMW x (4.54 plus 0.022 x KMW); roughly KMW x 5. The conversion formulas of KMW grades in alcohol content are a rough definition and only relatively accurate between 16 and 21 KMW:
The by Christian F. Oechsle (1774-1852) in the 1820s developed method or named after him unit of measure is mainly in Germany. Luxembourg and the Switzerland common. The Oechsle balance is usually calibrated to a temperature of 17.5 ° C. One 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)
The one by Adolf F. Brix (1798-1870) The method developed in 1870 or the unit of measure named after him is mainly used in English-speaking countries. The unit of measurement also used in English-speaking countries Balling is almost identical and is often expressed as "brix balling".
That by the French chemist Antoine Baume (1728-1804) and the unit of measure named after him is, inter alia, in the Mediterranean countries, inter alia 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 are pretty much in line with the possible alcohol content.
The ratios of the individual units of measurement are not linear to each other. They can therefore only be converted into each other using very complicated formulas. For this reason, mostly tables are used that often differ because of non-identical formulas. The table below shows the relationship of the three most important units of measure, as well as the sugar content and possible alcohol content. As a rule of thumb, 10 grams of sugar result in 0.66% alcohol by fermentation. This gives from 16.5 to 18 g of sugar about 1% vol. As a rule, white wines are at the lower limit and red wines at the upper limit.
|OECHSLE||BRIX||KMW||SUGAR g / l||ALCOHOL g / l||ALCOHOL%|
From the must weight can approximately the possible alcohol content be derived in the wine at (theoretical) complete fermentation of the sugar. Only approximate, because this depends on the composition. Two grape must with the same must weight do not necessarily have the same sugar content. A must with high amounts of acid and minerals has correspondingly less sugar compared to another must, which contains these in lesser amounts. Trockenbeerenauslese can reach 60 KMW or 300 Oechsle and more. Of course, in this type of wine, only a relatively small part of the sugar is fermented.
The Frenchman Victor Pulliat (1827-1896) drew up a classification for the classification of grape varieties in terms of their Mature timing and set the must weight as a comparison criterion. In Germany and Austria, must weight is an important quality criterion with which a wine is already classified by it alone. It is also for the award of the official test number (D) or state test number (Ö) of importance. In the two countries, however, it is given a little too much importance because there are also other important criteria (see below the country-specific minimum must weight values) Germany and Austria ).
In the warm winegrowing areas the must weight is not very meaningful. 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 at least as important role. Today is with the term physiological maturity the maturation (Ripe state) of the grapes described more broadly. Regarding the different ones analytical methods for the determination or measurement of the content of unfermented sugar ( residual sugar ) in wine, see below sugar content,