Beer basics
Beer is brewed from water, malted barley, hops and yeast.
Water is the most abundant ingredient. It must be of good quality. Mineral salts contained in brewing water are important for brewing processes and beer taste.
Malted barley gives beer its basic flavours. It provides the sugars that the yeast will ferment to produce alcohol. Malt also provides proteins, vitamins and minerals. Malt proteins are important for beer foam, body and mouthfeel. Barley is malted by first soaking it in water so that it germinates. The next step is to kiln the sprouted seeds. The time and temperature of kilning is varied to produce different types of malts.
Hops are the “flowers” of the hop vine. There are many varieties of hops, each with their own characteristic flavour and aroma. Hops are used to give beer bitterness, flavour and aroma.
Yeast ferment the sugars obtained from malted barley. Fermentation produces alcohol and carbon dioxide. Fermentation also contributes to the taste and mouthfeel of the beer. There are two basic types of brewers’ yeast: ale yeasts and lager yeasts, sometimes known as top and bottom fermenting yeasts respectively. There are many strains of both ale and lager yeasts. Different strains have their own flavour characteristics.
To brew the beer malt is first coarsely crushed. The crushed malt is mixed with hot water in a process called mashing. This activates enzymes in the malt which break down the malt starches to fermentable sugars. The malt is mashed at around 65º Celsius. By varying the temperature of the mash the brewer can control the way the enzymes work to produce either a dry or a sweet beer.
The mash is complete when all the malt starches have been broken down to sugars. The liquid, known as wort, is drawn off from the mash. Mash vessels have a false bottom made of slotted metal plate so the wort can be taken from beneath the spent grain. The spent grain is rinsed with more hot water to release the last of the sugars. The collected wort is then boiled. Traditionally the wort was boiled for 90 minutes. Hops are periodically added to the boiling wort.
After boiling the spent hops are separated from the wort which is then cooled by passing it through a heat exchanger. Yeast is added to the cooled wort, fermentation will start after about 4 to 8 hours. The yeast will ferment the wort in about 5 to 7 days for an ale, and about 7 to 10 days for a lager. After fermentation the young beer is then conditioned and matured before being packaged for drinking.
