The Method (or Madness?)
Beer is produced using a “batch” process. Production of beer using the “all grain” technique requires adherence to the following steps:
First, malted barley is crushed using a roller mill (technically it is not "milled" - the goal is to simply crack open up the barley kernel enough to allow water to access the nutrients inside; too fine of a crush will create a sticky substance that is challenging to work with).
Crushed barley is dumped into a big vessel known as a "mash-lauter tun" (MLT). Warm water is then added to the crushed, malted barley and allowed to sit for approximately one hour. This process activates the enzymes in the malted barley which break the complex carbohydrates present in the barley down into simple sugars that yeast can consume. This is known as mashing and the warm grain is known as the "mash".
Near boiling water is added to the mash, which heats up the grain bed and stops all enzymatic activity. Hot water is drained from the mash and poured back onto the top of the grain bed, which compacts, forming a natural filter. As warm water is recirculated through the grain bed (sparging), the runoff is continuously clarified while at the same time extracting all of the available sugar out of the grains.
The more sugar that is extracted, the more “efficient” the process. The carbohydrate-rich liquid that results from this process is known as “wort” and the process of permanently separating wort from grain (by draining the liquid from the grain bed, which sits on top of a slotted "false bottom," see above) is referred to as lautering. Once lautering is complete, wort heated to boiling and various ingredients, including but not limited to hops, are added.
Wort is boiled for 60-90 minutes. The timing of the hops affects their impact on the beer. Earlier additions of hops add bitterness but do not affect aroma (because volatile compounds are boiled off). Late additions of hops do not affect bitterness but impact aroma. Some hops are added after the boil – this is commonly referred to as “dry hopping.” Mashing to completion of the boil is referred to as the hot side of brewing.
At the completion of the boil, the wort must be cooled to approximately 80F so that yeast can be added (if yeast are added to boiling or even hot wort, the high temperatures kill the yeast). Once the wort has been chilled to ~ 80F, S. cerevisiae (ale yeast) are “pitched” onto the wort and stored for fermentation – after an initial aerobic phase, they begin to convert sugar and nutrients to ethanol.
The fermentation process takes approximately 10 days, after which very little fermentable sugar remains (most of it has been converted to ethanol) and the beer is ready for conditioning (during which yeast “finish” making the, followed by packaging / consumption.
The production of lager is similar but differs primarily in several respects. First, S. pastorianus (lager yeast) is used instead of S. cerevisiae (ale yeast). Because lager yeast tolerates colder temperatures, fermentation can occur at lower temperatures which reduces the production of off flavors and clarifies the beer. Similarly, because lager fermentation is slower than ale fermentation, higher quantities of yeast are “pitched” and fermentation takes longer. Thus it is more expensive to commercially produce lager as it requires more fermenters to make the same amount of beer