If you’re already a home brewer, then you can probably bore the tits off a fish going on and on about the brewing process and the difference between an ale and a lager (but we’ll get to that another time). If you’re not yet a home brewer (quit slacking and get on board!) then you may not even realise what the process is. You also might be interested to know that the brewing process is essentially the same whatever beer is being made, give or take an adjunct here or there, an open fermentation there and a decoction mash in between- but don’t worry about that!
Whatever your beer of choice, it pretty much boils down to four ingredients -malt, hops, water, and yeast. Other additives might be included, such as fruit or spices, but at the base these four are the primary ingredients of beer. The German Purity Law of 1516 (the Reinheitsgebot) stated that these were the only ingredients legally permitted- no additives.
Before absolutely everything, we start with malt. Barley is the most common grain, but brewers use wheat, rye, oats, rice, corn and various other starches in the brewing process. The barley is harvested and malted by a maltster (this is completely separate from the brewing process itself, and in only a very few cases would the maltster be the brewer- the maltster is also quite unlikely to be the farmer). The grain seeds are made to germinate, and this creates the enzymes needed to convert the starches contained within the grains into sugars which can be fermented. Before the grains can sprout, the maltster halts the germination process by heating and drying the grains. The malted barley may go directly to a brewer as what is called a base malt, or it may undergo additional roasting, which darkens the colour and changes both the aroma and flavour and is then usually called a specialty grain.
The brewer takes a base malt and may or may not add some specialty grains according to their recipe. He or she soaks the grains in warm water – this process is known as mashing. Different mash temperatures produce different types of sugars, which the yeast in turn break down differently. Some sugars are more fermentable than others, so the brewer must be careful to mash at the correct temperature. After the mash the grains are usually removed and rinsed with water to collect as much of the sugar that has been extracted from them as possible. At this point the sugary liquid is referred to as wort (pronounced wert).
The brewer now brings the wort to a boil in a large pot called a kettle. After the wort comes to a boil, hops are added in at different quantities and at different times. Hop additions often occur at numerous times during the boil; early additions contribute to the beer’s bitterness, while late hop additions provide the hop flavor and aroma. Sometimes hops are added before the wort is boiling (first wort hopping), and sometimes hops are added as the flame (or other heat source) is switched off (zero minute hop additions). In home brewing, the timing of the hop additions is expressed as the time remaining before the end of the boiling process, so a 60 minute hop addition would be 60 minutes before the end of the boil, and a 15 minute hop addition would be 45 minutes later, with 15 minutes remaining.
The wort which has now been battered with hops must be cooled before yeast can be added. Many would say that it must be cooled as quickly as possible, and on an industrial scale this is true, but it is increasingly popular in home brewing to allow the hot wort to cool naturally overnight. The brewer will strain out any sediment (hop residue for example) and transfer the cooled wort into a fermentation vessel where it will stay for a period of time. The vessel is designed to let gas (in the form of Carbon Dioxide mostly) escape without allowing any air or contaminants to come into contact with the beer by means of an airlock. The brewer adds yeast to the wort and then ensures the airlock is in place. The yeast consumes the sugars created in the mash and produces 2 key features of beer- alcohol and carbon dioxide. Once the yeast has consumed most of the sugars it settles to the bottom of the fermentation vessel. The beer is removed from the fermentation vessel and packaged.
There are a multitude of other steps that may or may not take place. The brewer may have to perform a special kind of mash such as step or decoction depending on the grains and the recipe being used. Hops may be added after the main fermentation has taken place- known as “dry hopping”. This gives beers like IPAs their signature aromas and flavours. The beer might be aged in a barrel to give it flavors of oak or whiskey. But for the most part, the steps above cover the process of brewing.
For further information, see John Palmer’s “How to Brew”, an excellent book on the science of homebrewing, which is made available free online. http://www.howtobrew.com/intro.html