What is the name of the process that converts sugar into alcohol?

The process that converts sugar into alcohol is fermentation. In alcoholic fermentation, microorganisms—usually yeast—break down sugars such as glucose into ethanol and carbon dioxide. The process allows yeast to produce cellular energy when oxygen is limited.

A simplified equation is: one glucose molecule becomes two ethanol molecules and two carbon-dioxide molecules. Yeast first uses glycolysis to split glucose into pyruvate; enzymes then convert pyruvate into acetaldehyde and finally ethanol. Carbon dioxide released along the way makes bread dough rise.

Fermentation is not the same as distillation. Fermentation creates the alcohol, while distillation later concentrates it by separating substances according to their boiling points. Different microbes and conditions produce different results: lactic-acid bacteria help make yogurt and sauerkraut, while yeast fermentation produces beer, wine, cider, and some fuel ethanol.

Louis Pasteur’s 19th-century experiments helped establish that fermentation is driven by living microorganisms rather than being simple chemical decay. Humans had used fermentation for thousands of years before understanding its biology.