SCIENTIFIC PROCESS

Each specific brewer and variety of beer will have slightly different brewing variations, though it all really comes down to a few basic reactions and processes.

Malting: This is the first step in the brewing process. Barley is soaked in water for two days then spread out to germinate. During germination, the plant releases highly active protease and amylase enzymes. The grains are then slowly heated to 80°C to stop the germination process.

Milling and mashing: The malted barley is then cracked open and mixed with water, which causes the enzymes to convert the starches in the grain to smaller, fermentable sugars and amino acids. These dissolve in the water and the resulting liquid is called wort.

Boiling: The wort is boiled to inactivate the enzymes and sterilise and concentrate the wort. The hops are then added for flavour. They also bond with the remaining peptides and proteins and act as a surfactant to reduce surface tension and stabilise the foamy head.

Fermentation: This gives the beer its alcohol content and carbonation. Once the hops are filtered out and the mixture is cooled, yeast is added. Over several days the yeast converts the sugars to carbon dioxide, ethanol and other substances that give beer its complex flavour. (For the chemistry boffins out there, here’s the equation for the reaction that takes place: C6H12O6 —> 2C2H5OH + 2CO2.) Most beer is around 4–6 per cent alcohol by volume (ABV).

Conditioning: Once fermentation is complete, beer is commonly stored for a few weeks, or up to a couple of months. This allows all the flavours to develop and the suspended yeasts and proteins to settle out. The beer is then cooled, filtered and packed in barrels, bottles and cans.