THE INS AND OUTS OF FERMENTATION
No new equipment is needed, as the beer is already fermenting
Congratulations - most of the hard work is now done! Do not relax too much though - the fermentation process can make or break your beer. The wort is the most exposed to the elements at the point of the process, and it's a race for your yeast to take effect before wild yeasts and bacteria alter the taste and aroma.
As the fermentation process progresses, you will identify each phase of the yeast life cycle.
The Fermentation Cycle
No two beers ferment the same, and neither do any two batches of the same beer. Your beer may take less than 24 hours to begin bubbling out of the air lock, or more than 3 days. Below is a real fermentation cycle from an amber beer that shows the full fermentation cycle day by day. Note that the regular fermentation picks up on Day 2, and that additional sugars are added to the fermenter on Day 7 that wakens the docile yeasts.
Day 1
Day 2 AM
Day 2 PM
Day 3
Day 4
Day 5
Day 6
Day 7 (Honey Added)
Day 8
Day 9
Day 10
Day 12
The Yeast Cycle
How yeast turns your wort into alcohol.
The Lag Phase
The yeast is consuming all available oxygen in your beer. Shaking your carboy at the end of the brew day allowed oxygen to enter your beer. The yeast flourishes off this oxygen. While the yeast is hard at work, the oxygen consumption is not a visible process and there will not be any indicators that this process is working effectively until the growth phase begins.
Once the yeast consumers most of the oxygen in the environment, strengthening itself in the process, it begins to consume the sugars in the wort. As sugars are broken down, yeast outputs two notable byproducts: alcohol and carbon dioxide. From the brewer's perspective, there will be two, very clear, indicators this process is underway. The bubbler will begin working. At first, you'll note outward pressure, as all the water in the bubbler will be in the outer section. Then, the bubbler will bubble - slowly at first, then rapidly with just a couple of seconds between each bubble. Air within the fermenter is escaping, and some aromas, normally sweet, will escape, too. You will also note a foam forming on the surface, which will expand and cover the entirety of the surface fairly rapidly. As the growth phase progresses, the foam will start to turn brown - this is normal.
The Growth Phase
The Fermentation Phase
Quickly following the growth phase, the fermentation phase strips the rest of the oxygen from the environment. As the carbon dioxide bubbles rise, remaining oxygen is 'scrubbed' from the solution.
The Sedimentation Phase
As the yeasts run out viable sugars, they enter a form of hibernation. The yeast flocculates, sinking to the bottom of the container to form a noticeable, normally white, layer of sediment. Note that the yeast is not fully dying during this phase, and that the yeast will have a large impact on the bottling stage of the process.