How is alcohol made?

Ethanol is commercially produced using a process called fermentation. Many other alcohols can be made this way, but are more likely to be produced by synthetic routes - from natural gas, oil or coal.

Fermentation is the process in which yeast breaks down sugar into alcohol and carbon dioxide. Yeast are tiny single-celled fungi that contain special enzymes responsible for this reaction.

The word equation for this process is:

Glucose + yeast alcohol + carbon dioxide

Carbon dioxide gas bubbles out of the fermenting solution into the air leaving a mixture of ethanol and water. It's important that no air is present or the yeast will produce ethanoic acid - the chemical found in vinegar.

Beer and lagers:

Barley, hops, water and live yeast produce beers and lagers. The sugar in the mix comes from the spouting barley. Bitter, stout and ale use top-fermenting yeast, while lager uses a variety that sinks to the bottom.

Wine:

In wine making the sugars come from the flesh of the crushed grapes. The type of wine produced depends on the type of grape used in the process.

Other Products:

Fermentation is also used in bread making; the yeast is mixed with the dough and kept warm. The carbon dioxide produced by fermentation makes the bread dough rise and the alcohol evaporates.