There are many tricks of the trade in the world of beer. Secondary fermentation is one. This is the process of siphoning off your beer after the initial rush of fermentation that happens. This leaves behind much of the yeasty sediment which comes out of your beer and sinks to the bottom of the fermentation vessel. This sediment contains dead yeast, and gluten from the barley, malt and other grains used in the making of the beer. This sediment can also be used as the yeast for your next batch of beer, if you brew quickly! Utilizing the process of secondary fermentation has many benefits.
The most prominent benefit of using secondary and even tertiary fermentation is that your beer will have a much purer taste. By leaving behind the sediment, one insures that this dead yeast doesn’t steep itself into the taste of your beer. There are many people who are highly sensitive to this yeasty flavor, and they will thank you for removing it from their beer. In some women, an overabundance of yeast in the diet can instigate yeast infections. This makes overly yeasty brew a health risk for some.
For the home brewer, the most recognized technique that can be used to eradicate a yeasty taste from your beer is secondary and tertiary fermentation. To do more, one would have to pasteurize ones ale – a difficult process for the home brewer. The process of Pasteurization heats the product, mostly while in the bottle or can, to boiling temperature and then back down to room temperature rapidly, killing off any remaining yeast or bacteria that might have crept into the product. The process of pasteurization has enabled many microbreweries to achieve just the right balance of sweetness and alcohol in their brews.
Now, back to using secondary fermentations! Your beer will have a much clearer look to it if you use this process. Amber will have a beautiful red clarity, showing off the fine colors roasted into the grains, while a pale ale will shine glowingly in the evening sun. With secondary and tertiary fermentation, the natural clarity of your beer will really come out. Even for the dark beers this is important, because the cloudiness that can ensue from sediment mixing will actually make the beer look less dark.
It is necessary for the homebrewed to have extra carboys and siphon hoses on hand if he or she wishes to use the process of secondary fermentation. I recommend leaving lots of room in a five or even six gallon carboy when your initial fermentation is starting – about one gallon’s worth of room – in any case. This ensures that as your beer bubbles over with foam in the initial fermentation, it will not foam out of the airlock. If the foam reaches the airlock in this stage of brewing, it can seriously jeopardize the antiseptic safeguards that protect the brew from unwanted bacterial infection. So, if you are making a 5 gallon batch of beer, it is a wise idea to split that up between two five gallon carboys, or a five and a three, or just use a six and leave plenty of room.
After the initial rush of fermentation (which usually takes three to five days), it is time to siphon out the beer into a new carboy. All the room you left the first time for foam now can be consolidated. Make sure that when you place your carboy(s) for the initial fermentation, they are on a table work bench, or somewhere up high, where you can later siphon them using gravity. If you move your carboy just before siphoning it into the secondary fermentation vessel, you will severely sabotage your efforts to leave behind the sediment. The jarring and sloshing will mix some of the sediment back into your brew, thereby negating the full effectiveness of the process of secondary fermentation!
Many home brewers will use their soda kegs as the secondary or tertiary fermenting vessels for their brew, and with the right timing, this can allow your brew to self carbonate with the malt sugars left over from the main fermentation.
All in all, secondary fermentation is a very important step towards refining your home brew. I recommend it for home brewers that want to take the next step in producing quality beers for family and friends.