Glossary
Fermentation
The metabolic process by which yeast or bacteria convert sugar into alcohol, acids, and CO₂ — the foundation of all alcoholic drinks and many non-alcoholic ones.
Yeast eats sugar and produces ethanol plus carbon dioxide. That single biochemical reaction underlies wine, beer, sake, makgeolli, kombucha, kefir, and the first stage of every spirit. Bacteria add a parallel pathway: lactobacillus converts sugar to lactic acid (yogurt, kimchi, sourdough); acetobacter converts alcohol to acetic acid (vinegar).
Fermentation length controls residual sugar and alcohol percentage. Stop early — sweet, low-ABV (makgeolli, off-dry wine). Run to completion — dry, higher-ABV. The choice is the brewer’s, and is the difference between most styles within a category.