How is Beer Made?

5/15/2008

The process of making beer is called brewing. There are four critical phases involved: mashing, lautering, boiling, and fermentation.

Mashing
During the mash, malted grain (typically barley or wheat, but many other grains can be used, allowing for some amazing flavor profiles) is mixed with heated water. The water activates enzymes in the grain, which converts the starches into various sugars. Some of these sugars can be consumed by yeast, producing alcohol and carbon dioxide during fermentation. Other sugars are long-chain sugars and cannot be consumed by the yeast – these sugars remain in the fermented beer and add body and a grainy sweetness (the taste referred to as “malty”). The brewer can control the rough ratio of fermentable to unfermentable sugars by adjusting the temperature of the mash water, controlling which enzymes in the grain are activated. Mashing at lower temperatures will produce more fermentable sugars, resulting in a drier, light-bodied, more alcoholic beer. Mashing at higher temperatures results in more body, more maltiness, and lower alcohol content. Aside from the grain selection, the mash temperature is one of the first creative decisions a brewer makes.

Lautering
After the mash, the mash water (now called wort or sweet wort, essentially unfermented beer) needs to be drained from the grain and collected for the boil. The process of separating the spent grain from the sweet wort is referred to as lautering. The first step in lautering is called the mashout – in this step, hot water is added to the mash to denature the enzymes and effectively stop the mashing process. This extra water also thins the mash and makes the next step, draining the mashtun, easier. As the initial runoff from the mash is being collected, the second step of lautering, called sparging, is performed – sparge means “to rinse” in German, and involves rinsing the mashed grains with fresh water. This makes sure none of the good sugars the mash produced are left behind in the mashtun – you want all that in the wort! Sparging as you simultaneously drain the tun slowly is the traditional method, called fly sparging. There is another method many homebrewers (including myself) use called batch sparging – in this method, the initial runoff is drained as quickly as possible from the tun. Then, an infusion of sparge water is added back into the mash, stirred, and drained as quickly as possible. Batch sparging is easier and takes much less time than a traditional fly sparge. However, it is not economical for large-scale professional breweries.

Boiling
The collected wort is then boiled – usually for at least an hour, although longer boils are becoming more common. The boil accomplishes several functions:

• it acts to sterilize the wort and kills any wild yeast or bacteria present
• it helps with the coagulation of various undesirable proteins (called hot break), which can then be left behind in the kettle instead of in the finished beer
• it drives off certain volatile compounds, such as DMS (dimethyl sulfide), ketones, and harsh hop compounds, which can cause off-flavors in the finished product
• it extracts, isomerizes, and dissolves alpha acids from the hops
• it stops any remaining enzymatic activity that made it past the mashout
• it can produce carmelization in the kettle, desirable in some styles of beer

The boil stage is where the brewer adds most of the hops. Hops can also be added to the wort as it is first drained from the mashtun (first wort hopping) or to the finished, fermented beer (dry hopping), but those are somewhat specialized techniques. For most beers, all the hops will be added to the kettle as the wort is boiling. As hops are boiled, their aromatic compounds are driven out of the wort and their bitter alpha acids are isomerized and dissolved into the wort. So, hops which are added early in the boil contribute bitterness to the beer, helping to balance the sweet malty flavor. Hops added late in the boil contribute aroma instead of bitterness, because their aroma doesn’t have time to boil off and their alpha acids don’t have time to isomerize. There are many varieties of hops, some of which are bred specifically as bittering or aroma hops. The brewer can create very different beers just by altering the amount of hops, the varieties used, and the length of time they are boiled.

Fermentation
The saying goes, “Brewers make wort. Yeast make beer.” After the boil, the wort is cooled down as quickly as possible and transferred into a fermentor. Once the wort is cool, infection becomes a concern – airborne bacteria and wild yeast would just love to belly up to that sweet wort, so care must be taken to keep anything that will touch the cooled wort sanitary. Once in the fermentor, yeast is added and the wort is oxygenated. Getting oxygen into the wort is essential at this stage, since the yeast need it to do their job, but it is worth noting that this is the only time oxygen is a friend of beer. After fermentation, exposure to oxygen can cause the beer to become oxidized, reducing its shelf life and producing a wet cardboard flavor which doesn’t go over well with most palettes. The fermentor is then sealed and fitted with an airlock to allow fermentation gases to escape while keeping oxygen and beasties out of the beer. Some beer is produced in open fermentors or by spontaneous fermentation by wild yeast and bacteria, but these are pretty specialized techniques which need the right environment to succeed…don’t try it in your basement, unless you like drinking a few gallons of vinegar. Once fermentation begins, the wort can now officially be called beer!

The yeast selection is also very important to the finished product – there are many specialized strains of yeast, each optimized to different fermentation temperatures and each contributing different flavorful esters to the beer. Some, like German Hefeweizen strains, are known for their esters, producing banana, clove, and bubblegum flavors. Others, like Kölsch yeasts, ferment very clean and produce a very crisp flavor profile, allowing the flavors of the grain and hops to steal the show.

Once the fermentation is complete, you have made beer! Of course, it is warm and flat beer sitting on a yeast cake, so the next steps involve transferring (or racking) the beer off the yeast into bottles or kegs, and carbonating the beer. Carbonation can be natural or forced. Natural carbonation involves adding a bit of sugar or unfermented wort to the finished beer. This allows the small amount of yeast still in suspension to produce some more carbon dioxide – in a sealed bottle or keg, this will create pressure, forcing the gas into solution. Forced carbonation involves hooking up a keg to a CO2 tank, which produces the same result, but in a shorter period of time. Homebrewers typically start out bottling their beer, so the natural carbonation method must be used. However, many people think naturally carbonated (or bottle-conditioned) beer tastes better, and many professional breweries produce bottle-conditioned beers as well.

Additional steps may be performed depending on the style of beer and brewer’s preference. Beer can be lagered or conditioned (aged) to allow it to clear and allow flavors to mellow – some very flavorful beers can taste almost undrinkable when brewed, but turn out wonderfully when given time to age. The beer may undergo secondary fermentation to allow for the addition of spices or fruit. Beer can also be filtered to produce a crystal clear beer (although you can accomplish this without filters) and to remove any yeast in suspension. Note that filtered beer cannot be naturally carbonated unless more yeast is introduced, since there will be no one around to produce that CO2!

There you have it – brewing in a very small nutshell. There are tons of caveats and subtle variations of the methods described, but I hope you will learn about that gradually by reading this site and other beer resources (this article is long enough already, no?). No two brewers create beer exactly the same way, and that is part of what makes this an amazing craft. It is a perfect combination of art and science.

Next time you crack open a bottle of your favorite brew, think about all the work that went into producing it. Then, go brew your own and create a beer no one has ever tasted before!