Bottling & Kegging
Before you will want to drink your beer you will want to carbonate it. There are two general ways you can do this; bottle conditioning and forced carbonation. Bottle conditioning is a generic term that refers to both natural carbonation and aging the beer, whereas forced carbonation refers to putting the beer under pressure with CO2 in a container such as a keg. Be sure to realize that natural carbonation can be done in a keg, and forced carbonation can be done before bottling.
When fermentation is complete, this only means that all the fermentable sugars have been consumed and converted by yeast; there are still yeast cells floating in the beer. You can take advantage of this, and the fact that a by-product of fermentation is CO2. All you need to do is introduce fermentable sugars into your beer to restart the fermentation process. There are two main ways to accomplish this; priming or kraeusening.
It is also important to note that if there is too much sugar available to the yeast when you seal the container, the yeast will continue processing the sugar until it is gone - even if the pressure exceeds the strength of the container. In other words, without careful attention paid, bottles can and will explode. The best way to avoid this is to first be certain fermentation is complete, and then avoid introducing too much sugar for priming. It is recommended to take at least three gravity readings, a day apart a piece; if the reading remains the same through three readings, you can be reasonably sure fermentation is complete.
The most common way to restart fermentation is to add a mixture of water and corn sugar or dry malt extract (DME) to the fermented beer. For a 19 Liter (5 Gallon) batch of beer, you will use 180 ml (¾ cup) of corn sugar or 300 ml (1¼ cups) of dry malt extract. More sugar can be used for a higher level of carbonation, but avoid using more than 240ml (1 cup) of corn sugar or 400 ml (1⅔cups) of DME. The measure of sugars should be dissolved into 0.5 l (1 pint) of boiling water, allowed to boil for a few minutes, and then quickly cooled to the temperature of the beer. Stir this mixture into the beer, carefully so as to avoid splashing and exposure to oxygen.
Some experts state that you should "rack," or let sit, the primed beer for about 24 hours before bottling to allow fermentation to restart, however in practice, it seems that as long as the newly added sugars are sufficiently mixed into the beer, consistency will be fine, and the time from priming to enjoying will be the same. The most notable problem with priming beer is the introduction of new flavors that would not be in the original wort. This can impart a subtle flavor that will exist in beers that otherwise would be completely different. The best way to avoid this is to kraeusen your beer.
Priming Tablets (Carbonation Tablets) or "Primetabs" are an advanced method of priming beer in homebrewing, They are small, sanitized corn sugar tablets which come in packages of usually 250 tablets per package, and are used when bottling your beer. Some priming tablets also contain DME (Dried Malt Extract) in the tablet with the corn sugar. When bottling your beer you usually add from 1 to 5 primetabs to a regular 12 oz / 330 ml bottle, depending upon how much carbonation you desire. 2 for lowly-carbonated beers like British Ales, and up to 4 or 5 for highly carbonated beers like Hefeweizen and others. There is typically no boiling or other handling required - simply put the desired number of tablets in the bottle, fill with beer, then cap, and that's it. Some priming tablets like Coopers Carbonation Drops only require 1 tablet per a 12 oz [345 -375 ml] bottle so be sure to read the package directions before using. For example, Munton's CarbTabs are different in amount of tablets required verses Cooper's Carbonation Drops. The tablets can be added before or after filling as there no difference either way. However, once the bottle is capped it should be turned on-end 2 or 3 times until the tablets dissolve in the liquid. After the bottle is capped in the first few hours, it is good idea to swirl or tip the bottle end to end to ensure a good mixture throughout the bottled beer. This ensures that the added priming sugars are accessible to the remaining yeast in the bottle, then the bottles can be left in a dark 60F to 70F (15C to 20C) environment for the standard week or two, which is long enough for the carbonation to develop in the bottled beer.. For best results the bottle should sit for two weeks. The only downside with priming tablets or "Primetabs" is their price tag, as they are usually more expensive than your regular run-of-the-mill corn sugar that is typically used to prime beer with.
Kraeusening requires a bit of fore thought, before you pitch yeast to your wort. The idea is to save a portion of the unfermented wort from fermentation and then add it back to the fermented beer before bottling. This allows you to add more sugars for the yeast to consume without introducing unnatural (to that specific beer at least) flavors. If you use fining agents at boil time (such as Irish moss) this has the added effect of reintroducing some of those fining agents back to the beer and can help clarity and reduce haze.
The saved wort is called gyle, and due to the fact that worts will vary in fermentable sugar content from beer to beer the gyle will have a variable sugar content. Because of this you must calculate the amount of gyle needed at the end of the boil, just before pitching yeast. This requires the use of a hydrometer. First, take a gravity reading of the wort at pitching temperature, after adding any waters to bring the wort to the desired volume (usually 19l or 5 gallons). Subtract from this reading 1 and then multiply that number by 1000. In other words drop the 1.0 from the front of the reading, so that a reading of 1.065 becomes 65. Then divide the volume by this number, and then multiply this number by 3 to find the volume of gyle needed. For example, a 19l (5 gal) batch of wort has a gravity reading of 1.040: (19liters/40) x 3 = 1.425 liters of gyle or (5gal/40) x 3 = .375gal = 1½ quarts of gyle.
It is imperative to store this gyle in a sealed container to avoid contamination by bacteria or wild yeasts. Once you are prepared to bottle, you will use the gyle in the same fashion you use the corn sugar or DME and water mixture. It is not necessary to reboil the gyle, but be sure the temperatures of the gyle and beer are as close as possible to the same, so as to avoid shocking the yeast.
Beer can be put under pressure in a keg, usually higher than pressure required to dispense beer from the keg, and held there for a day or two.
The two accepted ways of filling bottles is by siphoning into the bottles or using a special bucket with a spigot in the side. Many home brew supply stores carry a special bottle filling tube that has a valve which allows you to push the tube to the bottom of the bottle to open the valve and gently move the tube out of the bottle to stop flow. These tubes work both with spigots and siphoned bottling. There is another benefit of these tubes, in that by using one to fill the bottle to its brim, the bottle will have the perfect ullage once the tube is removed.
Ullage is an important consideration when filling bottles, to maintain consistency in levels of carbonation. Ullage is the small space between the surface of the beer and the cap. The ideal amount of ullage is about an inch.
If you are siphoning, use a siphon lock, that pinches the hose, to control flow. If you are using a spigot, attach a length of hose, so that filling starts at the bottom of the bottle. It's important not to splash the beer around, because doing you will aerate the beer. After filling, loosely place the caps on the bottles. Wait about 15 minutes before crimping the caps so that escaping and newly formed carbon dioxide can push the oxygen out of the top of the bottle.
There are a variety of kegging systems, from tap and pump traditional beer kegs to soda-pop keg systems with CO2 tanks to "party pigs", which are 2.5 gallon plastic bottles which use co2 cartridges to perform force carbonation and dispensing functions.