Brewing

Brewing is the production of beer through steeping a starch source (commonly cereal grains) in water and then fermenting with yeast. It is done in a brewery by a brewer. Brewing has taken place since around the 6th millennium.

Ingredients

The basic ingredients of beer are water (liquor), a starch source, such as malted barley able to be fermented (converted into alcohol) a brewers yeast to produce the fermentation and a flavoring, such as hops to offset the sweetness of the malt.

Brewing Process

There are several steps in the brewing process, which may include malting, mashing, boiling, fermenting and packaging. Most breweries already buy malt from a maltster that is ready to use for the brewing process. Mashing converts the starches released during the malting stage into sugars that can be fermented. The milled grain is mixed with hot water into what we call a mash tun. The mix will create a cereal mash. During the mash stage the naturally occurring enzymes present in the malt convert the starches into fermentable sugars. The result of the mashing process is a sugar rich liquid called wort. The wort is then strained through the bottom of the mash tun into a kettle for the boiling process. As the wort is being transfered from the bottom more water (liquor) is added to the top, a process called sparging. Once we have extracted all the wort we need, we then go onto the next stage.

Boiling

After the mashing stage the wort is boiled and the hops are added (and other flavorings if used) in a vessel called a copper / kettle, the boiling process is where chemical and technical reactions take place including sterilization of the wort to remove unwanted bacteria and also releasing the hop flavors, bitterness and aroma through isomerization, and also stopping the enzymatic process, precipitation of the proteins and wort concentration.

Wort Cooling

After the copper has finished the wort has to be cooled to around 20-26 celsius before the yeast is added, in modern breweries this is acheived through a plate heat exchanger. A plate heat exchanger has many ridged plates which form to sperate paths. The wort is pumped into the heat exchanger and goes through every other gap between plates, the cooling medium (usually water) goes through the other gaps. The ridges in the plates ensure turbulent flow. A good heat exchanger can drop 95 deg to 20 deg while warming the cooling medium from about 10 deg to 80 deg in a matter of a few seconds. The heat exchanger is also a good source of energy recovery for the following days brew.

Fermentation

Fermentation in brewing is the conversion of carbohydrates and carbon dioxide or organic acids using yeasts bacteria or a combination thereof, under anaerobic conditions. A more restricted definition of fermentation is the chemical conversion of sugars into ethanol. After the wort is cooled and aerated yeast is added to it and it begins to ferment. It is during this stage that sugars won from the malt are metabolized into alcohol and carbon dioxide, and the product can be called beer for the first time. After the fermentation has finished the yeast needs to be cooled to stop the fermentation process and is now ready to be put into either cask or keg depending on the brewery.

Packaging

The beer is now ready to be process into cask or keg – in our case cask. The beer is put into the casks size required and finings are added to aid the clearing process, the beer also goes through a secondary fermentation process whilst in the cask as it converts the sugars left behind after fermentation.