# Must weight

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{{Short description|Measure of sugar in grape juice}}
'''Must weight''' is a measure of the amount of [sugar](/source/sugar) in [grape](/source/grape) juice ([must](/source/must)) and, hence, indicates the amount of [alcohol](/source/ethanol) that could be produced if it is all [fermented](/source/fermentation_(wine)) to alcohol, rather than left as [residual sugar](/source/residual_sugar).<ref>[http://www.deutscheweine.de/icc/Internet-EN/nav/171/17117d71-9ffe-401e-76cd-461d7937aae2 Deutsches Weininstitut: Must weights] {{Webarchive|url=https://web.archive.org/web/20110726003824/http://www.deutscheweine.de/icc/Internet-EN/nav/171/17117d71-9ffe-401e-76cd-461d7937aae2 |date=2011-07-26 }}, accessed on March 26, 2009</ref>

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

===Refractometer scales===
[[Image:Refractometer.jpg|thumb|A classical hand-held [Brix](/source/Brix) [refractometer](/source/refractometer).]]

* [Brix](/source/Brix) (°Bx): Used in [Italy](/source/Italy), [France](/source/France), and [Canada](/source/Canada).
* {{ill|Klosterneuburger Mostwaage|de}} (KMW): Used in [Austria](/source/Austria). The scale is divided into '''Klosterneuburger Zuckergrade''' (°KMW). However, the KMW measures the exact sugar content of the must.
* [Normalizovaný moštoměr](/source/%C2%B0NM) (°NM): Used in the [Czech Republic](/source/Czech_wine), and [Slovakia](/source/Slovakia).

===Hydrometer scales===
[[File:Saccharometer.jpg|thumb|upright|A [relative density](/source/relative_density) [saccharometer](/source/saccharometer) in a sugar solution, 1040 g/L.]]

* [Baumé scale](/source/Baum%C3%A9_scale) (Bé°): Occasionally used in France and by [U.S.](/source/United_States) brewers.
* [Oechsle scale](/source/Oechsle_scale) (°Oe): Used in [Germany](/source/German_wine), Luxemburg and [Switzerland](/source/Swiss_wine). It is an important part of the [German wine classification](/source/German_wine_classification).
* [Relative density](/source/Relative_density): Used in the [United States](/source/United_States) (although Brix is sometimes used).

==Measuring must weight==
Must weights are commonly measured in the vineyard to monitor the [ripeness of the grapes](/source/ripeness_of_the_grapes), which helps select the time of harvest. For this purpose, it is usually measured by using a [refractometer](/source/refractometer). 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 measure [refractive index](/source/refractive_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](/source/Concentration)
*[Sugars in wine](/source/Sugars_in_wine)
*[Winemaking](/source/Winemaking)

==References==
{{reflist}}

Category:Winemaking

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Adapted from the Wikipedia article [Must weight](https://en.wikipedia.org/wiki/Must_weight) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Must_weight?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.