Unit of measurement for expressing the relative density or specific gravity of grape must, i.e. the mass (weight) in relation to volume. This mass, also known as extract, consists of the substances dissolved in the grape must. This is mainly sugar (fructose, glucose), but also acids, minerals, phenolic compounds, proteins and others (some of these substances are then found in the total extract of the wine). The specific gravity of grape must is always greater than 1.0 (water), the difference is largely due to the sugar content. The difference between "weight of a certain volume of must" and "weight of the same volume of water" is called weight ratio. The measurement is carried out by means of hydrometers (plummet), pycnometers and refractometers (refraction of light).
Different units of measurement are in use in the individual countries; the most common ones are
Klosterneuburg must scale (KMW)
The method was developed by August-Wilhelm Freiherr von Babo (1827-1894) in 1861 at the Klosterneuburg Viticulture Institute on the basis of the saccharometer invented by Carl Joseph Balling (1805-1868). This unit of measurement is mainly used in Austria, Hungary, Italy and some eastern states. 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 KMW degrees to alcohol content are a rough determination and only between 16 and 21 KMW relatively accurate:
The method or unit of measurement developed by Christian F. Oechsle (1774-1852) in the 1820s is mainly used in Germany, Luxembourg and Switzerland. The Oechsle balance is usually calibrated to a temperature of 17.5 °C. One degree Oechsle (Oe) is defined as the increase in weight of 1000 millilitres of must by 1 gram. One litre of must with 50 Oe weighs 1050 grams.
Brix or Brix-Balling (Bx)
The method or unit of...