The content of alcohol in wine refers to the share ethanol; the main existing alcohol. The possible or theoretically achievable alcohol content of a wine can already in the grapes by the Mostgewicht be calculated. He results from the sugar (Fructose and glucose) in the must, which in the fermentation in alcohol and carbon dioxide is converted. In the 19th century, the French chemist Joseph Gay-Lussac (1778-1850) developed a system that shows the alcohol content in degrees (°), which is still used in Anglo-American countries. Today, international standard and standardized within the EU, however, is the indication in volume, The measurement takes place at a temperature of 20 ° Celsius.