Fermentation Basics
How Fermentation Works
Learn the basic role of yeast, fermentable sugars, temperature, and process control.
Yeast turns sugar into more than alcohol
In alcoholic fermentation, yeast metabolizes fermentable sugars and produces ethanol, carbon dioxide, heat, and many flavor-active compounds. Different yeast strains and conditions create different outcomes.
Fermentability matters. Not every dissolved solid can be consumed by yeast, so original extract alone cannot predict exactly how far gravity will fall.
Conditions shape the result
Temperature, oxygen availability at pitching, pH, nutrients, and yeast health all influence fermentation. Follow strain-specific guidance and use clean, sanitized equipment.
A vigorous airlock is not a measurement of completion. Use a hydrometer or another appropriate instrument and confirm stable readings.
Package only when ready
Residual fermentable sugar can continue fermenting after packaging. In sealed containers, the resulting carbon dioxide can create excessive pressure.
Confirm stable gravity, use suitable bottles or kegs, and follow a tested process for carbonation or sweetening. Keep a batch log to improve repeatability.