There are healthy bacteria, which will not make you sick, and harmful bacteria, which will make you sick. It feeds additional germs and oxidizes the beer, altering its taste. It just takes a few days after adding oxygen (air) to the keg for the flavor to change dramatically.
When you open a bottle of beer that has been in storage for several months, it is very likely that some kind of bacteria will be living inside it. This bacteria eats the alcohol and other ingredients found in the beer, producing gases such as carbon dioxide and ethanol (beer alcohol). As these gases build up inside the bottle or can, they push out against the liquid, forcing it toward the top. This is called "fizz" and it's what makes your beer so refreshing! However, if you don't release this pressure, the bacteria will continue to grow and eventually cause problems for you and your beer.
Beer, like soft beverages, will get flat and lose its taste, fragrance, and bite with time. However, there are a few critical elements to consider while utilizing a keg that will ultimately lengthen the life of the beer you are serving. The first thing you should know about what happens to beer when you put it in a keg is that at any point during your service, you can pop the top and pour yourself a glass! Once the keg is full, pressure will push the beer out through the tap. You will want to let the keg sit for 30 minutes after each use before re-pressurizing it.
Once the keg is pressurized, it needs to be maintained at roughly 5 psi. If the pressure gets too low, the foam on the top of the beer will collapse which will cause it to spill out into the tank. Also, if the pressure gets too high, it could cause the lid to blow off. When you are not serving beer, you should leave the keg empty or nearly so to allow any remaining pressure to escape. This is called "de-pressuring" the keg.
As mentioned, beer will become flat if it is not served soon after it is made. This means that if you are making a lot of beer and don't immediately serve it, it will eventually go bad.
Is it really necessary to keep my keg cold? Yes, in virtually all circumstances, the beer keg must be kept cool. If you don't keep it cool, it won't be as refreshing on a hot day. Second, allowing it to get warm, or even hot, for a lengthy period of time may cause it to sour and taste foul. Finally, if the keg is allowed to get too hot, it may explode! That's right, an empty keg can heat up very quickly when left out in the sun, and once it reaches 140 degrees F (60 C), it will eventually blow up.
In most cases, this will require some type of kegerator. A kegerator is a refrigerator designed specifically for kegs. These units are extremely efficient at keeping the keg chilled because they use the same principles that large refrigerators do. Warm air rises, so by placing the keg below ground level and away from heat sources such as radiators, you prevent it from becoming warm.
In addition to being kept cool, your keg should also be maintained at a consistent temperature, which is why many brewers include a thermostat with their kegerator. The thermostat controls a compressor or other device that brings cold air down from above the unit. This creates a stable environment within the kegerator that allows the beer to be served consistently cold.
Bad beer will not make you sick; it will simply taste awful. The only way beer may make you ill is if the equipment used to create it is unclean or improperly used. For example, if a brewery uses rotten wood as part of its brewing process, then that material will produce alcohol that contains bacteria that can make you sick if you consume it.
The most common cause of bad beer is contamination. This can be done by using unclean equipment, such as fermenters that are not sanitized after use, or bottles that are not cleaned properly after processing. It can also occur when the brewer drinks while working at the tap room or pub. This is known as "tasting" beer and can lead to making substandard choices that may affect overall quality.
If this happens often, then the brewery should be notified so that they can fix their problem. Also, be sure to avoid drinking any beer that has not been approved by a professional tasting panel. These panels typically include former drinkers who have now become certified by organizations like the Beer Judge Certification Program (BJCP) or the Cicerone Certification Program (CCP). They will give an honest assessment of your beer's flavor and quality.
You may also want to consider getting some expert advice before going ahead and throwing out a case of beer.
A keg will normally survive at least 6-8 weeks if chilled in a CO2 kegerator before losing its fresh flavor. Pasteurized beer will keep for at least three months, and occasionally up to six months, if stored at the proper conditions. Unpasteurized beer has a shelf life of only two months. Beer that is exposed to light or heat will eventually lose its color and flavor.
Beer that has been exposed to light should be kept out of direct sunlight to prevent it from becoming brownish-yellow or amber-colored. This colored beer isn't actually harmful to drink, but it won't taste as good as it could. If you have any doubt about what state your beer is in, then don't drink it. It's better to know now than when you get a buzz on!
If you want to extend the life of your beer, then try not to let it come into contact with any other substances that might cause problems for it. For example, if you store your beer in a closet with other items such as socks and shoes, this could lead to some mildew growing inside the bottle. This mold will produce carbon dioxide as part of its metabolism process, which will then replace the lost gas within the bottle and cause it to explode.
The best way to ensure your beer remains tasty for as long as possible is by keeping it cold. A keg will usually freeze fairly quickly if placed in a cold area of your house or garage.