Öchsle scale

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The title of this article contains the character Ö. Where it is unavailable or not desired, the name may be represented as Oechsle scale.

The Öchsle Scale is a hydrometer scale measuring the density of grape must.^[1] It is named for Ferdinand Öchsle and it is widely used in the German, Swiss and Luxemburgish wine-making industries. On the Öchsle scale, one degree Öchsle (°Ö) corresponds to one gram of the difference 1kg (the weight of 1 litre of water) minus the weight of one litre of must at 20 °C. For example, must weighing 1084 grams per litre has 84 °Ö. The weight difference between must and water is almost entirely due to the dissolved sugar in the must. Since the alcohol in wine is produced by fermentation of the sugar, the Öchsle scale is used to predict the maximal possible alcohol content of the finished wine.

Based on the Öchsle scale there is a very strict and well defined classification of German white wines (Qualitätswein mit Prädikat). The classification is as follows (ranges due to the fact that different wine making regions have different minima):

Kabinett - 70-76 °Ö

Spätlese - 76-90 °Ö

Auslese - 83-100 °Ö

Beerenauslese - 110-125 °Ö (affected by Botrytis)

Trockenbeerenauslese - 150+ °Ö (affected by Botrytis)

Eiswein - 110-125 °Ö (Eiswein is made by late harvesting grapes after they have frozen on the vine and not necessarily affected by Botrytis)

In Austria the Klosterneuburger Mostwaage (KMW) scale is used. The scale is divided into Klosterneuburger Zuckergrade (°KMW), and very similar to the Öchsle scale (1 °KMW =~ 5 °Ö). However, the KMW measures the exact sugar content of the must.

The Baumé scale is occasionally used in France and by U.S. brewers, and in the New World the Brix scale is used to describe the readings of a refractometer when measuring the sugar content of a given sample. All of these methods are similar and the differences are more cultural than significant, but all are equally valid ways to measure the density of grape must and other sugar based liquids.