The journey from grain to bottled beer displays a fine balance between science and art. There are many variables of the brewing process which help contribute a wide variety of flavours.
Such combinations are tried and tested by brewmasters across the globe to ensure unique and distinguished beers. However, the basic brewing process is consistent.
Barley undergoes a malting process in which the grain is steeped in water to promote germination. Malting ensures the release of enzymes such as amylases and proteases which later during the brewing ensure the breakdown of starch and protein. This process is generally carried out at a “maltings” separate from the brewery.
In the brewery, the malted grain is milled and then combined with hot water in a process known as ‘mashing’. The correct proportions of water to grain at the correct temperature for the right amount of time allows for the grain’s enzymes to turn the starch into fermentable sugars. The mash is filtered in the lauter tun to remove the grain husks, producing a sweet liquid, known as “wort”.
The wort is then boiled in a large kettle in which hops or hop products are added to provide the bitterness and hop flavour of the final beer. The boiling sterilises the wort and kills micro-organisms, evaporates water to allow for concentration of the wort, enables the removal of proteins and tannins, and intensifies the colour.
The ‘hopped’, or bitter, wort is then cooled before yeast is introduced to begin fermentation. Different types of yeast impart different characteristics to beer and are specially chosen by the brewer for particular products. The sugars from the wort provide a carbohydrate source for the yeast. Their growth is further supplemented by amino acids and peptides from the malt, vitamins, inorganic ions and water. The sugars and nutrients from the wort are converted to ethyl alcohol by the yeast which also creates carbon dioxide.
The brewers control the temperature during the fermentation period and once a particular ‘gravity’, or sugar content, is achieved, the fermented bitter wort is further cooled and the yeast is removed. The residual carbohydrates provide body and flavour to the beer. Cooling allows for the yeast particles to settle out of what is then referred to as ‘green beer’.
The green beer (fermented bitter wort) is then conditioned into mature beer. The conditioning process helps improve the flavour, and is important in ensuring consistency.
After maturation, the beer is treated to ensure clarity, filtered and sent to the bright beer tank. Most beer is pasteurised whether it is in keg or in packages such as bottles and cans.