The brewing of beer takes place in several stages.
- Mashing: ground barley malt is soaked in hot water. This revives the barley enzymes, which break starch into sugar chains and sugars, and protein into amino acids. The result is a sweet, brown liquid called the wort.
- Boiling: hops are added to the wort, and the two are boiled together. This treatment extracts the hop resins that flavor the beer, inactivates the enzymes, kills any microbes present, deepens the color of the wort, and concentrates it.
- Fermentation: yeasts are added to the cooled wort and allowed to consume sugars and produce alcohol until the desired levels of each are reached.
- Conditioning: the new beer is held for some time to purge it of offflavors, clear it of yeasts and other materials that give it a cloudy appearance, and develop carbonation.