Lots of people like drinking beer, but it's a fair bet that most of them have only a hazy idea of the rather elaborate procedure by which it is made. Rebecca Crawford and I developed this hands-on brewing workshop to try to demystify the process.
The core idea of the workshop is to start from first principles (dry malted barley, hops, water and yeast) and to take the brewing process as far as the production of the wort (the sweet liquid which, when fermented, becomes beer). The workshop participants then take away a litre of wort home in a 2-litre PET bottle and ferment it at home.
The workshop
If you aren't familiar with brewing, you might want to read the short description of the process further down the page.
We performed an abbreviated mash (about 45 minutes), spent about 30 minutes sparging, and then did a short boil lasting about 45 minutes. We then cooled the wort and ran it into PET bottles, which the participants took home, along with a little yeast.
Brewing is like fighting a war or being a goalkeeper: there are long periods with nothing much to do. We filled these parts of the workshop with brewing-related activities, including but not limited to:
- A short talk about starch and sugar, and about what goes on in the mash.
- A beer-tasting. We used kits kindly provided by Williams Brothers, brewers in Alloa. Each kit has 4 bottles, brewed to identical recipes except for the use of different hops.
- Science-based pub tricks (eg how to stand a drink can on its corner).
It took three of us 90 minutes to clear up. Room for development here...
Brief guide to the brewing process
Beer offers three experiences to the drinker: flavour, alcohol, and fizziness (carbon dioxide). The flavour comes from hops (a climbing plant related to cannabis) and from barley. The alcohol and carbon dioxide are produced when yeast ferments sugars derived from the starch in barley.
The process of brewing can be broken down into 5 stages. Stages 1 and 2 are about turning the starch in the barley into sugars, and developing some of the barley-based flavours:
- Malting. The barley is soaked in water and held at a controlled level of dampness and humidity over a number of days until it starts to sprout. During this process, enzymes are produced which can convert the starch in the barley into sugars. However, before the enzymes have done much of their work, the malt is dried and roasted to stop the conversion. It is in this condition that the malt arrives at the brewery.
- Mashing. Hot water is added to the malt to create a porridge-like mixture. The enzymes created during malting swing back into action and continue to break down the starch into sugars. Depending on the mashing time and conditions, the desired balance can be achieved between the production of maltose (a simple sugar easily fermented by yeast) and dextrins (long-chain sugars that don't easily ferment and which provide body and flavour to the beer). In ordinary brewing, the mash lasts about 90 minutes. At the end of the mash, the liquid is drained from the grains, which are then rinsed (or sparged) with more hot water.
Stage 3 of the process is (largely) about adding hop flavour to the beer:
- Boiling. The sweet liquid that runs off the mash is then boiled with hops for upwards of an hour. During this period bitter compounds are extracted from the hops, along with other flavouring compounds which give beer its familiar taste and aroma. In addition, much miscellaneous complex chemistry goes on in the boil. The end result of the boil is a bitter-sweet liquid called wort (rhymes with Bert).
Stage 4 is about producing alcohol and carbon dioxide:
- Fermentation. The wort is cooled and yeast is added. Over a period of a few days, the yeast turns nearly all of the maltose in the wort into alcohol and carbon dioxide.
In Stage 5, the yeast is cleared from the beer by various processes, which is bottled or casked after a widely-varying period of maturation.