The Brewing Process
The brewing process begins with the soul of beer: Malt. It is a primary building block on which the entire multiple-step brewing process is built—the starting point for flavors, aromas and textures that emerge to create an almost unlimited selection of brewed excellence. It starts when brewers generally purchase malted barley from a variety of maltsters—those who prepare malt for brewers to use in their beers—in the United States, Canada and Europe. Maltsters vary in size from multinational to regional micro brew maltsters. A brewer chooses a malt type—or more typically, multiple malt types— and determines the quantity (a key element of the process) to use as the starting point for his intended brew.
The malt is then milled to prepare it for mashing. A malt mill—commonly called a “grist mill” or “grain mill”—cracks open the husk of the malt kernels to expose the starches inside in preparation for mashing. Some brewers may opt to completely de-husk the malt during milling for reduced bitterness and astringency and increased smoothness in the finished beer. At the end of this process—cracked and optionally de-husked—the malt grain is now called “grist.”
The brewer transfers the grist to the first brewing vessel, the mash tun, and water (sometimes called “liquor”) is added using two distinct methods—infusion or decoction. It is during this process that the natural malt enzymes break down the grist’s starches into simple sugars. If the brewer takes the infusion route, he adds grist to water and applies steam to the mash tun to reach desired temperatures. (The malt-grist mixture is called “mash.”) At times, the mash may “rest” at certain temperatures. Part of the brewer’s art is to choose the right temperatures and rest at those temperatures to get the best results in body and alcohol desired for the beer.
With the decoction mashing process—used historically and to this day by German and Czech brewers for brewing lagers, as well as by some American brewers—it involves another vessel called a “mash kettle.” A portion of the mash is transferred from the mash tun to the mash kettle where it is boiled and then returned to the mash tun with the balance of the mash. Possibly repeated several times, boiling the mash adds body to the beer and can produce more desirable malty flavors, such as caramel and toffee. The malty mash may also caramelize in the kettle, ultimately adding to the beer’s color and flavor. After this process, the completed mash is transferred to the lauter tun.
“Lauter” is German for “to clarify,” so lautering is the process of separating the sweet, sugary liquid mixture, called “wort,” from the mash. The lauter tun has a screen-like false bottom on which the grain husks and other mash solids settle and form a natural filter. This allows the wort to flow through via gravity and separate from the mash. “Sparging” involves rinsing the bed of solids on the false bottom with heated water to extract as much of the fermentable and unfermentable sugars as possible into the wort. This is important, since sugars determine the beer’s original gravity (OG) and play a significant role in fermentation. The remaining “spent grains”—what’s left of the solids after lautering—are generally transferred to farms to be used as nutritious cattle feed. Remember, no alcohol has been produced to this point in the brewing process. One more step remains before fermentation.
Wort is transferred to the brew kettle where it is brought up to a vigorous, rolling boil during which the wort is sterilized. Brewers then add hops to the kettle, generally in a minimum of three separate intervals during a 60 to 120-plus minute boil period. Bittering hops are added at the beginning of the boil to extract the bitter alpha acids, and generally, the longer the boil the more hop bitterness is extracted. Flavor and aroma hops are usually added during the final 10 to three minutes of the boil, respectively. Any remaining enzyme activity in the wort halts during the boil, and the wort produces its full color and flavor from the very high temperature. Once the boil phase is complete, the boiled and hopped wort goes into a whirlpool or hop back followed by a heat exchanger.
The whirlpool phase occurs once the boil is complete. This settling step may take place in the brew kettle, but in large breweries it is generally in a separate vessel. This further clarifies the wort by removing the “trub” (protein and hop solids, pronounced “troob”) from the wort through the formation of a solid trub cone in the center from the whirlpool and settling action. In some breweries, a hop back may be used. The hop back employs a layer of fresh hop flowers in a sealed chamber. Hot wort from the brew kettle flows through the hop back, where the fresh hops filter out the trub and provide the additional benefit of adding more hop aroma compounds to the wort. A hop back is generally used when whole flower hops are used in the boil, while a whirlpool will effectively capture smaller particles left by pelletized hops. Once the trub has been removed, the wort passes through a heat exchanger where it is brought down to fermentation temperatures on its way to the fermentation tank. The cooling water in the heat exchanger captures the heat from the wort (the heat literally exchanges), and for efficiency, many breweries then store this newly heated water to begin the next brewing cycle (step 3) or to use for other purposes.
It’s now time for yeast, the life of beer, to perform its magic on the sugary and hopped wort. The wort is transferred to the fermentation tank where it is brought to the starting temperature specific to the type of beer being produced. The yeast is then pitched into the tank and fermentation—the conversion of sugars to alcohol and CO2—begins. This is the primary fermentation, and once it’s underway, the liquid can rightfully be called beer. Fermentation activity produces heat and increases the temperature of the wort. The brewer monitors and controls the temperature closely, as it directly impacts the aroma and flavor compounds—the esters—produced by the yeast, which factor in the finished beer’s character. Warmer temperatures promote ester development. Generally speaking, two major yeast types exist in the brewer’s tool kit: ale yeast, which is also referred to as “top fermenting” yeast, and lager yeast, which is “bottom fermenting” yeast. Ale yeast strains tend to do their fermentation work at warmer temperatures (59° - 69°F) and rise to the top of the wort, often producing esters resulting in a more fruity, sweet beer compared to most lagers. Lager yeast strains generally do their work at cooler temperatures, around 45° - 60°F, and can process more sugars, resulting in a well attenuated, clean (low to no esters), and dry beer. The beer that has finished primary fermentation is called “green beer” or “young beer,” as it needs to be matured or aged for one to several weeks prior to packaging.
“Kräusen” is a German word that refers to a traditional German lager brewing process in which actively fermenting wort from a new batch of beer is added to a finished green beer to cause a secondary fermentation in the green beer. Kräusening is an additional, optional step that can take place in the fermentation tank, the storage/conditioning tank or a separate tank. During the cold conditioning step (also called “lagering;” lagern means “to store” in German) after primary fermentation, the yeast becomes dormant. Kräusening infuses active yeast to bump up the natural carbonation of the beer. Additional benefits include balancing the beer’s flavors by means of the yeast cleaning up undesirable byproducts of the primary fermentation, including diacetyl, acetaldehyde and other volatile compounds. Kräusening can also add body and smoothness to the beer.
The storage or conditioning phase period varies, depending on the type and style of the beer. It can range from one to six weeks or longer. This process allows the beer to mellow and mature, with all of the flavors fully developing and melding together to create the beer that ends up in your glass. The brewer may elect to add dry hops or fresh wet hops to the beer during this step to capture more hop aroma and flavor character. Wooden barrel aging is an additional step the brewer may take after the conditioning period to add unique wood and spirit aroma and flavor complexities to the beer’s character.
When conditioning is complete, the beer may be filtered to remove any remaining yeast and other matter, such as protein, to create a clear “bright” beer. This beer may then be stored in what’s called a “bright beer” tank. Some brewers leave all of their beers unfiltered—and some are generally intended to be unfiltered, such as many wheat beers. In other cases, some brewers pasteurize their beer prior to packaging.
While just a snapshot of the process behind the taste and aroma of your favorite beer, this illustrates the care and handling that goes into each glass of your favorite brew. After this process, however, the remaining effort belongs to you. So pick up your favorite brew—or experiment with a new one—and raise a glass to the process and the individuals behind the character of the beer inside.