The lag phase is the period of time in which yeast adapts to the new fermentation environment and undergoes significant reproduction. Depending on the state of the yeast (reactivated, chilled, or dried), health of the yeast cells, variety of yeast, amount of dissolved oxygen available in the wort, temperature of the wort, and amount of available fermentable sugars, the lag phase may last anywhere from 2 to 24 hours. The lag phase begins as soon as the yeast is introduced into the wort and very little CO2 or alcohol is produced while it is active.
The shorter the lag time, the better, so that the desired yeast has a chance to take control of the wort before unwanted bacteria or wild yeast strains do.There are several ways to decrease your lag time, including:
- Creating a yeast starter
- Rehydrating dried yeast
- Keeping your yeast and wort at the correct temperature when pitching the yeast and continuing to monitor temperature until the lag phase has ended.
- Well-aerating your wort so that the yeast will have enough oxygen available.
- Pitching enough yeast for the gravity of your wort.