The Brewing Process
All beers are brewed using a process based on a simple formula. Key to the beer making process is malted grain, depending on the region traditionally barley, wheat or sometimes rye.
Malt is made by allowing a grain to germinate, after which it is then dried in a kiln and sometimes roasted. The germination process creates a number of enzymes, notably alfa-amylase and beta-amylase, which will be used to convert the starch in the grain into sugar. Depending on the amount of roasting, the malt will take on dark colour and strongly influence the colour and flavor of the beer. Breweries buy malt and this is not a process that is done in-house.
The malt is crushed in a malt mill to break apart the grain kernels, increase their surface area, and separate the smaller pieces from the husks. The resulting grist is mixed with heated water in a vat called a “mash tun” for a process known as “mashing”. During this process, natural enzymes within the malt break down much of the starch into sugars which play a vital part in the fermentation process. Mashing usually takes 1 to 2 hours, and during this time various temperature rests (waiting periods) activate different enzymes depending upon the type of malt being used, its modification level, and the desires of the brewmaster. The activity of these enzymes convert the starches of the grains to dextrines and then to fermentable sugars such as maltose.
A mash rest at 104 °F or 40 °C activates beta-glucanase, which breaks down gummy beta-glucans in the mash, making the sugars flow out more freely later in the process. A mash rest from 120 °F to 130 °F (49 °C to 55 °C) activates various proteinases, which break down proteins that might otherwise cause the beer to be hazy. But care is of the essence since the head on beer is also composed primarily of proteins, so too aggressive a protein rest can result in a beer that cannot hold a head. This rest is generally used only with undermodified (i.e. undermalted) malts which are popular in Germany and the Czech Republic, or non-malted grains such as corn and rice, which are widely used in North American beers. Finally, a mash rest temperature of 149 to 160 °F (65 to 71 °C) is used to convert the starches in the malt to sugar, which is then usable by the yeast later in the industrial brewing process. Doing the latter rest at the lower end of the range produces more low-order sugars which are more fermentable by the yeast. This in turn creates a beer lower in body and higher in alcohol. A rest closer to the higher end of the range creates more higher-order sugars which are less fermentable by the yeast, so a fuller-bodied beer with less alcohol is the result. Finally the mash temperature may be raised to 165 °F to 170 °F (about 75 °C) (known as a mashout) to deactivate enzymes. Additional water may be sprinkled on the grains to extract additional sugars (a process known as sparging).
After the mashing, the mash is pumped to a lauter tun where the resulting liquid is strained from the grains in a process known as lautering. The lauter tun generally contains a slotted “false bottom” or other form of manifold which acts as a strainer allowing for the separation of the liquid from the grain.
At this point the liquid is known as wort. The wort is moved into a large tank known as a “cooking tun” or kettle where it is boiled with hops and sometimes other ingredients such as herbs or sugars. The boiling process serves to terminate enzymatic processes, precipitate proteins, isomerize hop resins, concentrate and sterilize the wort. Hops add flavor, aroma and bitterness to the beer.
At the end of the boil, the hopped wort settles to clarify using hop filters. SBM does not use the whirlpool system for hop separation.
The wort is then moved into a temperature controlled cylindrical-conical “fermenter” where yeast is added or “pitched” with it. The yeast converts the sugars from the malt into alcohol, carbon dioxide and other components through a process called fermentation or glycolysis. After a week to three weeks, the fresh (or “green”) beer is cooled close to freezing temperature, yeast is purged and the beer is allowed to “lager” or rest. After this conditioning for a week to several months, the beer is often filtered to remove remaining yeast and particulates. The “bright beer” is then ready for serving or packaging.
Ale (top-fermenting yeasts)
Ale yeasts ferment at warmer temperatures between 15°C and 20°C (60°F to 68°F), and occasionally as high as 24°C (75°F). Pure ale yeasts form a foam on the surface of the fermenting beer, because of this they are often referred to as “top-fermenting” yeast – though there are some ale yeast strains that settle at the bottom. Ales are generally ready to drink within three weeks after the beginning of fermentation, however, some styles benefit from additional aging for several months or years. Ales range in color from very pale to black opaque.
Lager (bottom-fermenting yeasts)
While the nature of yeast was not fully understood until Emil Hansen of the Carlsberg brewery in Denmark isolated a single yeast cell in the 1800s, brewers in Bavaria had for centuries been selecting these cold-fermenting Lager yeasts by storing or “Lagern” their beers in cold alpine caves. The process of natural selection meant that the wild yeasts that were most cold tolerant would be the ones that would remain actively fermenting in the beer that was stored in the caves. Some of these Bavarian yeasts were stolen and brought back to the Carlsberg brewery around the time that Hansen did his famous work.
Lager yeast tends to collect at the bottom of the fermenter and is often referred to as “bottom-fermenting” yeast. Lager is fermented at much lower temperatures, around 10°C (50°F), compared to typical ale fermentation temperatures of 18°C (65°F). It is then stored for 30 days or longer close to the freezing point. During the storing or “lagering” process, the beer mellows and flavors become smoother. Sulfur components developed during fermentation dissipate. The popularity of lager was a major factor that led to the rapid introduction of refrigeration in the early 1900s.
Today, lagers represent the vast majority of beers produced, the most famous being a light lager called Pilsner which originated in Pilsen, Czech Republic (Plzen in Czech language). It is a common misconception that all lagers are light in color: lagers can range from very light to deep black, just like ales.
Beers of Spontaneous Fermentation (wild yeasts)
These beers are nowadays primarily only brewed around Brussels, Belgium. They are fermented by means of wild yeast strains that live in a part of the Zenne river which flows through Brussels. These beers are also called Lambic beers.
Beers of mixed origin
These beers are blends of spontaneous fermentation beers and ales or lagers or they are ales or lagers which are also fermented by wild yeasts.