Acetifikationen

Acetifikationen, in English often called acetification or acetic fermentation, is the biochemical process by which ethanol is oxidized to acetic acid by acetic acid bacteria. It is essential in vinegar production and can occur in other alcoholic liquids that are exposed to air.

The primary microorganisms are species of Acetobacter, with Gluconobacter playing a lesser role in some contexts. Acetobacter can oxidize ethanol all the way to acetic acid, whereas Gluconobacter tends to accumulate intermediates in some cases. The process is aerobic, relying on oxygen as the electron acceptor, and is carried out by membrane-bound enzymes that transfer electrons to oxygen.

The mechanism proceeds in two enzymatic steps: ethanol is oxidized to acetaldehyde by alcohol dehydrogenase, and acetaldehyde is further oxidized to acetic acid by acetaldehyde dehydrogenase. Energy is produced by the oxidative metabolism of the substrate, while the main end product is acetic acid.

Controlled conditions are important for industrial and artisanal acetifikationen. Aerobic conditions with sufficient oxygen transfer, moderate temperatures (roughly 25–30°C), and a low pH environment (approximately 2–3) favor the process. Ethanol concentration is typically in the several percent range; too high levels can inhibit the bacteria, while too low levels slow fermentation.

Applications and context: In industry, submerged fermentation in aerated bioreactors is common for large-scale vinegar production, whereas traditional surface cultures are used in some artisanal settings. The resulting product is primarily acetic acid and water, with flavor compounds reflecting the substrate and fermentation conditions. Proper control of temperature, oxygen supply, and pH is important for product quality and consistency.