There are some amazing transformations that occur when making beer. While the process and/or ingredients may differ slightly, depending on style, the following describes the process of making beer: from grain to glass.
Barley
Barley is a cereal grain, like wheat, that’s grown around the world, including Canada (mostly, on the prairies), that is used in a number of food products like breakfast cereals and as feed for farm animals. But about half of all the barley grown will be used to make beer.
Malt
Barley cannot be made into beer until it’s malted.
Water is sprayed over the cleaned, dried barley grains (i.e., seeds). Just like what would happen in moist soil, over a few days, the grains absorb water and start to germinate. Just as the grains start germinating, the maltster halts the process by drying out and kilning the grains resulting in malt.
The process of malting the barley causes some amazing things to happen in the seeds. As anyone on the Atkins diet will tell you, cereal grains like barley are full of starch, a carbohydrate which is quite inert and stable: seeds can stay viable for years as long as they’re kept dry. When the seeds absorb water and begin to germinate, a biological process is initiated that prepares chemicals in the seeds, called enzymes, to break down the starches in the seeds into sugars, which they then use to generate the energy to grow.
By stopping the seeds from growing just after they start to germinate, the maltster halts the growth of the seed, but leaves behind all the prepared enzymes that will convert the grain’s starch to sugar. Effectively, the maltster transforms seeds that want to become barley plants into malt that wants to become beer. Maltsters are good people.
Mash
The malted barley is a rich package of starch and the enzymes necessary to transform that starch into (fermentable) sugar.
The malt gets coarsely milled and hot water is added to it, producing the mash, which often resembles an overly wet porridge. Particular temperatures activate particular enzymes that break down particular compounds in the malt. The brewer brings the mash to a temperature that activates the enzymes to break down the complex starch carbohydrates into simple sugars. The more malt in a recipe, the more sugar is extracted from the mash (and ultimately, the more alcohol is produced).
Usually, after about an hour of mashing, the starch in the malt has been converted to sugars, and the sweet wort solution is ready to be drained away from the mashed grains. More hot water is used to rinse the mash of its remaining sugars in a process called sparging. The wort is collected in pot and is now ready to boil.
Boil
The sweet wort is heated until boiling. Boiling the wort does a few things including concentrating the sugars in the solution, but most importantly (especially to craft beer lovers), hops enter the brew now.
Hops are responsible for a few different beer characters. Firstly, hops impart bitterness to the beer. This is important because the bitterness offsets the sweetness inherent to the sugars in the wort. The longer hops are boiled, the more bitterness they add to the beer. Bittering hops are often boiled for about an hour. The more bittering hops in a recipe, the more bitter the beer will be.
Like herbs add flavours to food, hops also provide beer with distinctly ‘hoppy’ flavours (besides bitterness). In the same way there are many varieties of apples, from Granny Smith to Red Delicious, there are many hop varieties whose flavours range from spicy to grassy to flowery to citrusy depending on their origin and growing conditions. Boiling the hops for a shorter amount of time, for example for 10 minutes, provides the beer with hoppy flavours.
When hops are boiled for a very short time, one minute or less, they impart a lot of hoppy aromas to the beer – think back to the bright-green, citrusy aromas you get when you stick your nose into a glass of local IPA. Still more hop aroma can be added to a beer through a process called dry-hopping – when hops are not boiled at all, they’re added to the fermenting beer.
Ferment
After the wort is boiled, it’s cooled down to fermentation temperatures. For ales, that’s about 68F (20C), for lagers, it’s about 50F (10C).
We’re now going to talk about the least sexy (and most time consuming) part of brewing… cleaning. Once the wort is cooled, the sugary, room temperature solution is a paradise for all kinds of nasty bacteria and wild yeasts. Everything that touches the wort from here on should be thoroughly cleaned and sanitized so as to minimize its exposure to bacteria and other organisms that will produce off flavours (or worse) in the beer. To a great extent, the quality of the beer you make will be directly proportional to how well you clean and sanitize your equipment.
Brewing yeast is added to the wort and fermentation begins: the yeast consumes the sugars in the wort and produces byproducts including carbon dioxide and alcohol. Put another way, the brewer makes the wort, but the yeast make the beer. Brewing yeast and baking yeast are fundamentally the same organism and operate the same way (baking yeast consumes carbohydrates in bread dough and releases CO2, that creates the bubbles in the finished bread). Over the years, particular varieties of yeast have been isolated and selected for the flavours they produce when used to make (different styles of) beer.
Over a few weeks, the yeast continues eating away at the sugars, increasing the quantity of alcohol in the beer while the CO2 vents off.
After the yeast has had its fill, the beer’s ready for conditioning (i.e., carbonating) and packaging (i.e., bottling or kegging).
Carbonation
The yeast in the beer has worked its way through the sugar that was in the wort. At this point, the beer is pretty flat (due to the CO2 venting off during fermentation) and pretty cloudy (due to suspended yeast in the solution). To get to the carbonated and clear beer that we’re used to, the beer needs to be conditioned.
Classically, beer is conditioned by transferring the beer into a sealable vessel like a cask, adding some additional fermentables and sealing the vessel to trap any CO2 that’s produced during the secondary fermentation. Under pressure, the CO2 dissolves into the beer and carbonates it.
Homebrewers often condition their beer by dissolving sugar into their fermented beer (called priming) and transferring it to bottles. The bottles are capped and kept out at fermentation temperature for a week or two while the remaining yeast ferments the new sugars and carbonates the beer. It’s then ready to refrigerate and drink. This process, where the yeast is responsible for generating the CO2, can be described as natural carbonation.
Alternatively, beer can be artificially carbonated. The fermented beer is transferred to kegs, sealed and pressurized with CO2 from a tank. Over time and under pressure, the added CO2 dissolves into the beer, carbonating it.
While the beer is conditioning (whether naturally or artificially), the yeast that’s been suspended in the beer during fermentation drops out of the beer (you may have noticed the layer of yeast at the bottom of your friends homebrew bottles).
Finally, after all these amazing natural transformations, the clear beer is ready to be served.