How beer is made: starches in grain are converted to sugars which are boiled with hops for flavor and bitterness. Yeast is added which changes the sugar into alcohol and carbon dioxide. Simple, huh? Now let's get into the real details...
1. Type of Beer: There are generally two types of beers: Ales and Lagers. The difference is the type of yeast used. Ale yeast ferments primarily from the top of the beer and at warmer temperatures (60-75'F). Lager yeast ferments from the bottom of the beer at lower temperatures (45-60'F).
Ales are typified by a rich, full bodied profile with a fruity nose and taste. Each strain has unique characteristics, which can be enhanced or minimized depending on formulation and fermentation temperatures. Lager beers are typically lighter and dryer than ales with a crisp finish. Lager yeast generally produce significant amounts of sulfur during cooler fermentation, which dissipates during aging.
Among each of the two types of beer, there are a great number of styles. The style of a beer can specify the color, the amount of alcohol, the bitterness, the balance of hops versus malt, and other characteristics. For example, a Stout is an ale with coffee-like roasted barley and roasted malt aromas. Esters are low to medium. Diacetyl is moderate to none. Hop aroma low to none. Deep garnet to black in color- clarity is irrelevant in such a dark beer. A thick, creamy, long-lasting head is characteristic.
2. The Recipe: Once you have chosen the style of beer you want to brew, you can choose how much of certain grains and hops you want to use. Each ingredient will lend a certain characteristic to your beer whether it be for flavor, color, bitterness, etc. In the above example of Stout, roasted barley is a type of grain which adds a dark color and coffee-like flavor. While this is typical of stouts, roasted barley may not fit with another style of beer such as the lightly flavored and colored Kolsch.
The amount of ingredients will primarily affect the amount of alcohol you will end up with. For example, 8 pounds of barley will produce a beer with 4.1% alcohol/volume while 12 pounds of barley will produce a more potent beer with 6.2% alc/vol. Additionally, specific grains lend a different amount of fermentable material. Even the yeast used can affect the amount of alcohol produced.
3. Milling and Mashing: The purpose of the grain is to provide starch which can then be converted into sugars that the yeast turn into alcohol. This is accomplished through the use of enzymes that are already present in the grain. Mashing is the brewer's term for the hot water steeping process which hydrates the barley, activates the malt enzymes, and converts the grain starches into fermentable sugars. Crushing or milling the grain helps to hydrate the starches during the mash.
The temperature at which the mash (basically milled grain and water) is held determines which of two enzymes acts on the starches in the grain. A lower mash temperature, less than or equal to 150°F, yields a thinner bodied, drier beer. A higher mash temperature, greater than or equal to 156°F, yields a less fermentable, sweeter beer. This is where a brewer can really fine tune a wort to best produce a particular style of beer.
4. Lautering: Now you have a pot full of mash. The liquid, referred to as sweet wort, is ripe with sugars for your beer, but you need to separate that from the spent grain. A lauter tun consists of a large vessel to hold the mash and a false bottom or manifold to allow the wort to drain out and leave the grain behind. Lautering can be conducted several ways, but it usually consists of 3 steps. These are: mashout, recirculation, and sparging.
Mashout is the term for raising the temperature of the mash to 170°F prior to lautering. This step stops all of the enzyme action (preserving your fermentable sugar profile) and makes the grainbed and wort more fluid.
Recirulation: After the grain bed has settled and is ready to be lautered, the first few quarts of wort are drawn out through the drain of the lauter tun and poured back in on top of the grainbed. The first few quarts are almost always cloudy with proteins and grain debris and this step filters out the undesired material from getting in your boiling pot.
Sparging is the rinsing of the grain bed to extract as much of the sugars from the grain as possible without extracting mouth-puckering tannins from the grain husks. Typically, 1.5 times as much water is used for sparging as for mashing. The wort should be drained slowly to obtain the best extraction.
4b. Shortcut: For those just getting into brewing, you can do away with all this grain, starch, and sugar talk. You can buy Malt Extract at your local homebrew store (LHBS). Malt Extract is the same sweet wort you get from the above process, just concentrated into a syrup or powder. Typically malt extract is more expensive than the mashing process above and it gives you less control over your final beer, but it is an easy way to get started!
5. Boiling: Once your sweet wort (or malt extract) is in your brewing kettle, you can begin the boil. Boiling accomplishes a few things including killing any bacteria that may be present in the wort. The wort also has to be at a high enough temperature to extract the bittering oils found in hops. There is also an effect on protiens and other behind-the-scenes activity. After the wort has been boiled, anything that touches it must be sanitized. This prevents your beer from getting infected by the nasties that live all around us.
6. Hops: Hops have been cultivated for use in brewing for over 1000 years. Part of the early use of hops in beer was to preserve it. The bitterness contributed by hops balances the sweetness of the malt sugars and provides a refreshing finish. The main bittering agent is the alpha acid resin which is insoluble in water until isomerized by boiling. The longer the boil, the greater the percentage of isomerization and the more bitter the beer gets. However, the oils that contribute characteristic flavors and aromas are volatile and are lost to a large degree during the long boil. There are many varieties of hops, but they are usually divided into two general categories: Bittering and Aroma. Bittering hops are high in alpha acids, at about 10 percent by weight. Aroma hops are usually lower, around 5 percent and contribute a more desirable aroma and flavor to the beer.
7. Yeast: Brewer's Yeast (Saccharomyces) is considered to be a type of fungus. It reproduces asexually by budding- splitting off little daughter cells. Yeast are unusual in that they can live and grow both with or without oxygen. Yeast can live without oxygen by a process that we refer to as fermentation. The yeast cells take in simple sugars like glucose and maltose and produce carbon dioxide and alcohol as waste products.
Attenuation describes the percent of malt sugar that is converted by the yeast strain to ethanol and CO2. Flocculation describes how fast or how well a yeast clumps together and settles to the bottom of the fermenter after fermentation is complete. There are many different strains of brewer's yeast available nowadays and each strain produces a different flavor profile. The boiling wort must be cooled to around 70' F before adding (pitching) the yeast as high temperatures will kill the yeast as it killed the rogue bacteria in your wort.
8. Fermentation: There are two considerations that are needed to ensure that the wort has been properly prepared to support a good fermentation. The first is oxygen supplied via aeration. The second consideration is the level of amino acid nutrients in the wort, specifically referred to as Free Amino Nitrogen or FAN. Malted barley normally supplies all of the FAN and nutrients that the yeast need to grow and adapt to the fermentation environment. The third factor for a good fermentation is temperature. Yeast are greatly affected by temperature; too cold and they go dormant, too hot (more than 10°F above the nominal range) and they indulge in an orgy of fermentation that often cannot be cleaned up by conditioning. High temperatures encourage the production of fusel alcohols - heavier alcohols that can have harsh solvent-like flavors.
9. Secondary Fermentation: The Secondary Phase allows for the slow reduction of the remaining fermentables. Also, the yeast clean up some of the byproducts they produced during the fast-paced primary phase. Towards the end of secondary fermentation, the suspended yeast flocculates (settles out) and the beer clears. High molecular weight proteins also settle out during this stage.
10. Bottling: Ales are usually ready to bottle in 2-3 weeks when fermentation has completely finished. Sugar (usually dextrose or dry Malt Extract) is added to the finished beer and then bottled. The additional sugar provides the yeast with some food which they will use to produce carbon dioxide and carbonate the bottle. The bottle conditioning phase usually takes over a week to complete. Homebrewed beer has a fairly long storage life. Depending on the style and original gravity, the beer will keep for more than a year. Finally, it is important to keep the beer out of direct sunlight, especially if you use clear or green bottles. Exposure to sunlight or fluorescent light will cause beer to develop a skunky character.
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