Must weight

Must weightis a measure of the amount ofsugaringrapejuice (must) and, hence, indicates the amount ofalcoholthat could be produced if it is allfermentedto alcohol, rather than left asresidual sugar.

Measurement is in degrees

In France and many other countries, the grape must density is often recalculated to showpotential alcohol,the percent alcohol content that would be the result if the must were fermented to a completely dry wine.

Refractometer scales

A classical hand-heldBrixrefractometer.

• Brix(°Bx): Used inItaly,France,andCanada.
• Klosterneuburger Mostwaage(KMW): Used inAustria.The scale is divided intoKlosterneuburger Zuckergrade(°KMW). However, the KMW measures the exact sugar content of the must.
• Normalizovaný moštoměr(°NM): Used in theCzech Republic,andSlovakia.

Hydrometer scales

Arelative densitysaccharometerin a sugar solution, 1040 g/L.

• Baumé scale(Bé°): Occasionally used in France and byU.S.brewers.
• Oechsle scale(°Oe): Used inGermany,Luxemburg andSwitzerland.It is an important part of theGerman wine classification.
• Relative density:Used in theUnited States(although Brix is sometimes used).

Measuring must weight

Must weights are commonly measured in the vineyard to monitor theripeness of the grapes,which helps select the time of harvest. For this purpose, it is usually measured by using arefractometer.A few grapes are crushed between the fingers and the must is dripped onto the glass of the refractometer. The refractometer will be calibrated in a must weight scale, but as refractometers actually measurerefractive index(of the grape must in this case), the must weight scale on the refractometer is in effect an indirect measurement, with refractive indices having been pre-converted to their must weight equivalents.

See also

• Concentration
• Sugars in wine
• Winemaking