To learn all there is to know about brewing would take many years, and would probably involve getting one or more andvanced degrees. Luckily, that isn’t needed to enjoy beer. However, a cursory understanding of what happens in the brewhouse is useful for beer connoisseurs to have, since almost all of the flavors encountered while tasting beer were the result of what happened while it was being brewed. Below is a brief overview of the basic steps of beer brewing. If you haven’t yet checked out the ingredients section, you may want to look there too, since a lot of the information in that section is built on here.
The first thing a brewer needs to do before getting to work making beer is to ensure that their brewing grain is ready to go. Assuming they aren’t malting their own barley, this means milling, or crushing, the grains. This crucially important step can make or break a beer before it has even begun. The key is to crush the grains enough so that it exposes the starchy center of the barley seed without damaging the grain hulls that encase them. If the crush is too course, not enough of the starch will be converted to fermentable sugars. If the crush is too fine, the husks, which act as a filter bed for the brew will be destroyed, and the brew will become gummy and unusable.
Below is a picture of well-milled barley. Note how the barley kernels have been cracked into large pieces while the hulls have remained largely intact.
Once the grain has been milled, it is added to a large vessel called the mash tun, and mixed with hot water to form the mash. That’s when the magic starts to happen. The heat from the water (referred to as liquor in breweries) activates the enzymes within the barley. These enzymes then begin to convert the starches in the grains into sugars.
Since there are several different types of enzymes within barley, each with a preferred temperature at which they like to work, brewers monitor the mash temperatures extremely close. By raising and lowering the temperature of the mash, brewers can control what types of sugars are produced by the enzymes. At lower temperatures, highly fermentable sugars are created, resulting in dry beers. At higher temperaturs, the sugars aren’t as easily digested by the yeast, resulting in a beer with some sugars left unfermented, and thus a sweeter, more full-bodied end product. The enzymes work quickly too. Within about an hour they will be done converting starch to sugar, at which point the brewer will end the enzymatic activity by raising the temperature of the mash to over 200 degrees Fahrenheit, a process known as mashing out.
The next step in the brewing process is the take the mash, and separate out the spent grain from the sugary liquid known as wort (pronounced wert). This process is called lautering.
To begin the lautering process, the mash is transfered to vessel with a false-bottom called a lauter tun. Here the clear wort is drained away from the hulls and barley grist. Water is also added during lautering, in order to extract even more of the fermentable sugars from the grain. This is known as sparging. Sparging must be done very gradually as to not disrupt the grain bed that acts as a natural filter for the wort. Brewers typically add sparge water at the same rate as the wort is being drained below, although some English brewing methods call for completely draining the wort, then adding water and doing it all over again. This second go-round of lautering is called second runnings, and was historically made for small beers.
Brewers must be careful not the sparge for too long, as eventually the bitter tannins from the grain will also be stripped away.
Once the sweet wort has been separated from the grains, it is brought to a strong, prolonged boil for one to two hours. This boiling process is critical for many reasons. First, and from a historical point, most importantly, it sterilizes the beer. In today’s modern world, that seems fairly important, but for a long time this was quite literally a life-saver. For centuries people commingled their clean and run-off water supplies, leading their drinking water to become a town-well-sized petri dish for harmful bacteria. Of course, people didn’t understand this. They just knew the water was unsafe, and that something in the brewing process made water ok to drink. It’s for this reason that everyone drank beer, including small children.
Boiling does more than sterilize the brew, however. Hops introduced to boiling water will begin to break down, or isomerize, molecularly altering the composition of the acids within the hops and releasing bitterness into the beer. The longer the hops are boiled, the more of their alpha acids will be isomerized in order to lend bitterness to the brew. Hops added to the boil to lend bitterness are called early hop additions, and are generally allowed to boil in the beer for an hour or more.
Hops added later in the boil don’t bitter the beer all that much, but instead lend flavor and aroma. This is because in addition to alpha acids, hops also contain highly volatile, and very pungent oils, which break down quickly in boiling water. However if only exposed to the boiling wort for a short period of time, or at lower temperatures, hops will release these oils and lend aromatics and flavor to the beer. To extract flavor, brewers typically add hops about 10-15 minutes before the end of the boil. For aroma, hops are added even later, no more than 2 minutes before the end of the boil. Often aromatic hop additions even occur just after the boil ends.
Once the boil is completed it is sent to a whirlpool to collect any hop matter and coagulated proteins that have accumulated. Then it is immediately cooled. Cooling the beer quickly is important, since the beer will begin to oxidize and produce off flavors almost immediately at these temperatures.
Once the wort has been cooled, it is moved to a fermentor, which is usually just a large stainless steel vat (or on rare occasions, oak). Next yeast is added and the fun begins! From the moment the yeast is added it gets to work eating the sugars that were created during the mash. As they consume the sugar, the yeast expells carbon dioxide and alcohol, as well as a variety of flavor compounds that vary greatly depending on several variables such as the specific strain of yeast, and fermentation temperature of the beer. Fermentation time can vary greatly, from a few days for a simple ale, to over a month for lagers.
Fermentation is also where the brewer decides wether or not he/she will be brewing an ale or a lager. This decision is a simple choice of using lager yeast or ale yeast, although the brewing of the beer changes drastically depending on which direction the brewer goes.
If brewing an ale, which account for the majority of beers by style, the brewer will pitch ale yeast and let the temperature of the fermenting beer rise to a toasty 65-76 degrees – perfect for ale yeast. Also called top-fermenting yeast, ale yeast forms a thick layer pillowy foam at the top of the fermentation vessel. This is called a kräusen or pellicle, and if you didn’t know any better, you’d think it would kill you if you drank what was underneath it. But rest assured, there are no byproducts of beer, wanted or unwanted, that will hurt you (besides alcohol of course). This is a main reason why home brewing is legal. The worst you can do is make gross tasting beer!
If brewing a lager, the brewer must keep the beer much cooler, usually between 45 and 55 degrees. At these temperatures, the lager yeasts work slowly and efficiently towards producing a clean tasting beer with little flavors given from the yeast itself. Unlike ales, lagers yeast, or bottom fermenting yeast, do not form a pellicle at the top of the fermentation vessel.
Once the yeast has consumed all the available sugars, primary fermentation is over. While the beer is technically no longer fermenting, the yeast’s work is far from over. During the course of fermentation, several off flavors are created in addition to the production of alcohol and carbon dioxide. Common off flavors associated with under-conditioned or “green” beer is sulfur, butter, and green apples. Luckily, given enough time the yeast will absorb these off flavors. For ales, this conditioning can take a week or so. For lagers, whose yeast generally work more slowly, this can take months. To help speed up this process, some lager brewers employ the practice of kräusening, which is adding still fermenting wort (and the yeast inside it) to conditioning beer to help kick start the conditioning process.
Once fermentation is over, and the yeast have worked their way through the off-flavors, it becomes dormant and begins to settle to the bottom of the fermentation vessel. From here, the brewer can easily remove the yeast, leaving only bright, clear beer. To help this process along, many brewers also filter the beer mechanically, or by adding filtering agents which help collect the yeast into larger groups, which then fall out of suspension at a faster rate.
It’s easy to forget that the final step in the brewing process is packaging the beer. Luckily, brewers don’t forget this, or else we’d all be drinking directly from massive conditioning tanks (which now that I write it, sounds pretty awesome). In any regards, packaging is the process of putting the finished beer into vessels for mass consumption. Typically, beer is packing into bottles, cans, and kegs. Most brewers also force carbonate their beer just prior to packing, since they’ve allowed any CO2 developed during fermentation to escape into the atmosphere. Without allowing the CO2 to escape, the tanks could potentially rupture from the pressure build-up.
Some brewers practice bottle conditioning, meaning that instead of force carbonating, yeast and sugar are added to the beer after it has been packaged, to bring on a second fermentation inside the bottle, thereby adding depth of flavor, as well as carbonation. Bottle conditioning can also enhance the shelf life of beer, as the yeast will consume any oxygen that seeps into bottled beer.