Unit of sugar content in
wine, after
Ferdinand Öchsle, who invented a special
aräometer for that purpose.
The unfermented grape juice is classified by degrees Öchsle (°O), which allows for a good estimate regarding the quality of the wine that results from fermentation. While Germany and Switzerland use Öchsle, Austria, Hungary and Italy use the Klosterneuburg grape juice scale, after Freiherr A. von Babo.
Nowadays, the sugar content is measured by a refractometer.
Fifty °O (awful, sour stuff) are equivalent to a density of 1.060 g/m³ and a sugar content of 12.37 percent.
130 °O on the other hand (very good for a wine) are equivalent to 1.130 g/cm³ and a sugar content of 30.15%