Many homebrewers like to take advantage of a process called “secondary fermentation,” and claim that it improves the quality of their homebrew beer. Secondary fermentation, also known as two-stage fermentation, is simply transferring (“racking”) your homebrew from one fermenter to another. The optimal timing as to when to start the secondary fermentation is up for some debate, but it is about midway through the fermentation process. But why go through the trouble? Is putting your beer through a secondary fermentation really necessary. What are the benefits?
The Pros of Secondary Fermentation for your Beer
Here are a few of the benefits of secondary fermentation:
- It gets the beer off spent yeast sediment. After two or three weeks, yeast starts to break down and contribute off flavors to your beer. Most homebrewers don’t ferment their beer long enough to cause any noticeably problems, but for those who choose to do a longer fermentation, racking the beer into a secondary fermenter or carboy is highly recommended.
- It allows the beer to mature. Time allows the malt, hops, and yeast flavors to blend together and balance.
- It improves clarity by reducing the amount of sediment in the finished beer. Putting your beer through a secondary fermentation allows time for more yeast, hop trub, and protein to fall out of the beer. Adding a fining agent, such as gelatin, into the secondary fermenter can aid in this process significantly.
- It gives the homebrewer an opportunity to “dry-hop” — or “dry-spice” — their beer. Dry-hopping is just adding hops to the secondary fermenter, which contributes hop aroma to the beer. You can also take this opportunity to add spices, flavorings, wood chips, or other additives to your brew.
The Cons of Secondary Fermentation for your Beer
There aren’t many disadvantages to using a secondary fermentation, but they’re worth considering:
- It takes a more time and effort. Yes, it takes some time to transfer or rack your beer to a secondary fermenter. How long it takes varies depending upon your set-up, but usually the time it takes to transfer is much shorter than brew day or bottle day.
- There’s a risk of contamination. By opening your fermenter and passing your beer through a siphoning hose, you risk bacteria or wild yeast getting into your beer. But, as long as you practice good sanitation, you should be fine.
- Potential to lose hop flavor. Hop flavor degrades over time. In most cases, a few weeks won’t make a difference, but if you’re brewing a very hop-forward beer, the length of the fermentation period should be considered.
How to Transfer Your Beer for a Secondary Fermentation
To transfer your beer to a secondary fermenter, keep in eye on the bubbles coming out of the airlock and wait until the fermentation slows down (4-5 days). Clean and sanitize your secondary fermenter and transfer tubing, then add the beer to the secondary fermenter – usually a carboy – by siphoning. Re-seal with an airlock. In 7-14 days, bottle or keg your beer as you would normally.
Do you use a secondary fermentation when you homebrew? When do you start yours? How long do you leave it in the secondary? Leave a comment!
Til next time…Cheers!
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David Ackley is a beer writer, brewer, and self-described “craft beer crusader.” He holds a General Certificate in Brewing from the Institute of Brewing and Distilling and is founder of the Local Beer Blog.