Many grains can be used to brew beer. Without looking too hard, you can find beers brewed with wheat, oat, corn, rice, or rye. But without question, the undisputed king of brewing grains is barley, specifically malted barley.
Why is barley the brewing grain of choice? Well, as brewing Jedi Master Randy Mosher puts it, “Barley is the perfect brewing grain.” That’s because it naturally contains almost everything needed to make beer: high starch content, the enzymes needed to convert the starch to sugar, and proteins to aid in yeast health. Barley’s husks are even perfectly suited to act as a filter during the brewing process – which is crucial, as anyone who has ever had their brewing system gummed up with wheat or rye can tell you. Barley is so perfectly designed for making beer that anthropologists have suggested that the reason it was domesticated in the first place, roughly 10,000 years ago, was so that people could brew beer.
In addition to bittering the beer, the essential oils in hops lend beer a huge variety of flavors and aromas, ranging from earthy to herbaceous, or even tropical. And what’s really cool about hops is that the process for extracting their bitterness and the process for extracting their flavors and aromas are mutually exclusive. While the bittering alpha acids in hops are only released at boiling temperatures, these same temperatures will quickly dissipate the extremely volatile aroma and flavoring oils contained in the hop cone. Likewise, the cooler temperatures used to coax the aromatics out of hops are not nearly hot enough to dissolve (isomerize, technically) the bitter alpha acids. As a result, brewers have a huge amount of control over the hop character of their beer. If they prefer their beer to be malt driven, with just enough of a clean bitterness to balance out the brew, they will add the hops early on during the boil. Conversely, if a brewer wants to really highlight the aromatics of a beer without it being face-puckeringly bitter, they will add the hops just at the end of the brewing process. Usually it’s a combination of the two, with some hops added at the beginning and others at the end.
In Munich, the water had hardly any sulfates but instead was rich in carbonate. As a result, any hoppy beer the local brewers tried to make (and they certainly did try!) would turn out harsh and unpalatable. But that same local water’s rich calcium content helped to promote the soft, full mouthfeel of more malt-prominent beers such as dunkel.
On the opposite end of the spectrum, the Czech town of Plzen has water with almost no mineral content to speak of. This amazingly soft water allowed the bright, clean-tasting lagers of their namesake to dominate the world!
Today, modern brewing technology has given brewers from anywhere in the world the ability to analyze their own water source and adjust it as needed. In fact, it is now common practice in larger breweries to strip out all mineral content totally, only to add them back in precise measurements. Nowadays adjusting water levels is an ordinary step for any brew day.
Once introduced into unfermented beer (wort), yeast will immediately begin to consume the sugars from the malt. Yeast convert this sugar to alcohol, with an added byproduct being carbonation. To put it more crudely, yeast eat sugar, pee alcohol and fart carbonation!
Once the yeast have consumed all the available sugars in the beer, they will go dormant and slowly settle at the bottom of the tank, leaving clear beer above. This process is called “dropping bright, and is usually sped up by the brewer though the use of fining agents or mechanical filtering before packaging into bottles, cans, or kegs. This allows for a clear, bright final product.
Some beers are intentionally left in contact with the yeast, either to add flavor or to allow the beer to continue to condition after bottling. If you even see the term “bottle conditioned” on a beer, that means there was active yeast left or added to the bottle. Bottle conditioned beers can often be cellared for long periods of time to gradually evolve in flavor.
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.
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 temperatures, 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.
To begin the lautering process, the mash is transferred 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.
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.
Fermentation is also where the brewer decides whether 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 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.
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.
Thanks to the folks at The Beer Temple for providing most this information.