During fermentation, many microorganisms produce ethanol. The beverage industry exploits this process in the production of beers, wines, and distilled spirits. When humans consume ethanol it is metabolized in the liver. This metabolism of ethanol occurs in three main steps.
In the first step of metabolizing ethanol, alcohol dehydrogenase converts ethanol to acetylaldehyde and a molecule of NADH is produced. In the second step, acetylaldehyde oxidase converts acetylaldehyde to acetate and another molecule of NADH is produced. In the third step, acetyl-CoA synthase produces acetyl CoA from acetate and Coenzyme A. Acetyl CoA then enters the Krebs cycle.