Hi again, beer lovers! Here is the next segment in the intermittent series on home
brewing.
The previous segments were: Part 1 - ingredients, Part 2 - mashing, and Part 3 - Boiling the Wort.
This segment is Fermentation.
Before I go on: Homebrewing Part 5 is planned as "bottling/kegging", but I only know about bottling. Maybe one of the other homebrewers here, who kegs their beer, could write about the kegging process. Message me if you can help.
At the end of the previous stage, I had the wort, with yeast, in a carboy ready for fermentation to start. Then I move it to the fermentation cooler, check the thermostat, and ignore until the next day.
For the next weeks or months of fermentation, temperature control is important. In most of North America, for much of the year, ambient temperatures are too hot for brewing. If you don't live in a house with a basement you need a fridge dedicated to fermentation. This is because at above their favorite temperatures the yeast produce various chemicals other than ethanol and CO2, and nearly all of these cause noticeable off flavors. Ale yeast is typically happiest right around 60F, lager yeast more like 50F.
This ugly contraption is my fermentation cooler; the design was suggested by an article in
Brew Your Own. Basically it's a mini-fridge with the door taken off and a box built on the front big enough to hold a carboy. The flap of silver insulating material is the lid. You plug the fridge into the temperature controller, and put the probe in next to the wort. I add a digital thermometer to show me the actual temperature. The tiny refrigeration unit probably couldn't get that bigger space down to lagering temperatures, but it's adequate for keeping ale at 60F. In the coldest parts of the year I might have to put in a heating pad set to low to get the fermentation
up to 60F.
For the rest of the time the beer is fermenting, until you bottle or keg it, you will have an airlock sealing the container, so that the CO2 produced can escape without letting dust and germs in. For sanitary reasons a lot of brewers don't like to use water in the airlock; you could use sanitizer, but many use alcohol - the cheapest vodka is suitable.
In the first couple of days you may also have some foam coming out too, which can clog the airlock and blow it across the garage. If you're using a yeast known to be vigorous (such as wheat beer yeast) you might, instead of the little airlock, rig a big one, called a "blow-off tube, simply a large-diameter plastic tube running from the stopper to a pitcher full of sanitizer. Ale yeast is top-fermenting, so this foam is full of fresh healthy yeast and some brewers use it -- the commercial system a few brewers use to catch and reuse the overflow is called the
Burton Union.
|
For the next few days we watch the airlock to see how fermentation is coming. Within about 24 hours of pitching you should see a steady stream of CO2 bubbles coming out. After 3 or 4 days this should have slowed dramatically.
|
How long does fermentation take? The only answer is: until it's done. The only way to be sure is to use the wine thief to take a sample and measure it with the hydrometer. Most homebrewers don't take many samples just to avoid that loss of 4-6 oz of beer each time. A popular rule of thumb is called the "1-2-3" rule: 1 week "primary" fermentation, 2 weeks "secondary" fermentation, 3 weeks conditioning in bottle. This is accurate enough for most ales.
Homebrewers don't all agree about the process of primary and secondary fermentation.
Biologically fermentation is fermentation, it continues while there is sugar and live yeast.
"Secondary" fermentation is really about racking the beer off the yeast and letting it clear. Brew pubs often have what they call the "brite tank" between the fermenter and the serving tank; that's my secondary fermenter. Bigger brewers filter the product.
|
|
So after a week or so, I rack the beer out of the primary fermenter into another sanitized carboy. "Racking" is the process of siphoning the beer out of one container into another, leaving behind the sediment. The "racking cane" (left) has a spacer at the bottom so that it rests at the bottom of the carboy but then pulls the liquid from above the layer of yeast and sludge. Put an airlock on the new carboy and put it back in the cooler or in a cool place. If the recipe calls for "dry hops", they are added during secondary, in a mesh bag like you saw for boiling the whole hops. Other flavorings such as oak chips might also go in now. 2 weeks is a typical amount of time for this, but as long as you wait long enough for the yeast to finish this is really a matter of preference.
I've only brewed ales so far. A quick look at How To Brew tells me that to brew lager, primary fermentation might be about 3 weeks around 50F, and after racking, lagering for 6-8 weeks at 40F or below.
I'm drinking Oud Beersel Kriek. I've been drinking it while I've been finishing this diary and it's nearly gone; I'll have to go out for some more beer. What are you drinking? |
|