THE BREWING PROCESS
With a Degree in Biochemistry and an obsession for craft beer, our Head Brewer Mark combines science and creativity in the Powder Monkey Beers he creates.
The first step in the brewing process is mashing, where malted cereal grains (normally barley but also wheat, rye, oats etc.) are mixed with hot water that has been treated for use in brewing – termed ‘liquor’. The temperature of the mash is critical to allow the enzymes in malted barley to break down starch into simple fermentable sugar for the yeast as well as some more complex un-fermentable sugars. Typical infusion mash tuns normally operate with a single rest at around 65°C for 60 minutes, our steam heated mash mixer gives us greater control over the process and allows us to conduct multiple rests at different temperatures.
Once the enzymes in the mash have fully converted the starch to simpler sugars they need to be extracted from the grains in a process called lautering. Hot water is washed over the grains and the sugary liquid that is collected is called wort, the grain husks act as a natural filter to keep any unwanted substances from passing through to the boil kettle where the wort is collected. Our spent grain can then be collected and is used by local farmers as livestock feed, keeping the cycle of life going!
Boiling the wort serves a number of purposes, it sterilizes the wort and also drives off some unwanted off-flavours. Hops are added at this stage and the boiling process extracts bitterness from the hops, with hops added at the start of the boil contributing more perceived bitterness and hops added at the end of the boil giving more flavour and aroma. Most ales are typically boiled for around 60 minutes while lagers tend to have a longer boil of 90-120 minutes.
‘Brewers make wort, yeast make beer’. This is where yeast takes over and boiled wort must be cooled to allow the yeast to be pitched and fermentation to begin. Yeast is a living organism and each strain works best at specific temperatures for a given style of beer. The primary fermentation will last 4-6 days where the yeast will consume all the fermentable sugars and produce alcohol and carbon dioxide. Yeast also produces many by-products during fermentation that contribute to the flavour and aroma of the beer and each yeast strain will have a unique flavour profile. It has now become common for hops to be added at this stage in a process called ‘dry hopping’ where much more of the aroma compounds from hops can be retained without being boiled off.
Once fermentation is complete the beer, often called ‘green beer’, can be given additional time to allow the yeast clean up any unwanted off-flavours that may have been produced during fermentation. The beer can then be cooled to around 0°C which encourages the yeast to clump together in a process called flocculation and settle to the bottom of the tank, where the yeast can be re-claimed and used to pitch into another brew. Further cold conditioning can encourage more settling of yeast and proteins that will clarify the beer and also allow flavours to develop and round out. This period of maturation can range from days or weeks for ales through to months for lagers and even years for certain styles of beer.
Finally the conditioned beer is ready to be transferred into packaging. For cask ales beers may be transferred straight from the fermenter to the cask to allow for a secondary fermentation that gives cask ale its unique flavour and mouthfeel. Beer can also be filtered or directly transferred to a ‘brite beer tank’ where it can be carbonated and packaged into keg, bottle and can.