Term for the unit of measurement used to represent the relative density or specific gravity of grape must. This expresses the mass (weight) in relation to the volume. The mass, also known as extract, consists of the dissolved substances such as fruit pulp particles 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 the "weight of a certain volume of must" and the "weight of the same volume of water" is called the weight ratio. The measurement is carried out by means of areometer (plummet scales), pycnometer and refractometer (light refraction).
There is a vast number of sources on the web where one can acquire knowledge about wine. But none has the scope, timeliness and accuracy of the information in the encyclopaedia at wein.plus. I use it regularly and rely on it.
Sigi Hiss
freier Autor und Weinberater (Fine, Vinum u.a.), Bad Krozingen