The process of making beer follows five separate steps:
- Conversion- Unfermentable starch is converted into fermentable sugar.
- Extraction- the malt is soaked in order to bring the sugars into solution.
- Flavouring- the sweet solution is flavoured with hops.
- Fermenting- the sugar is converted into alcohol by the action of yeast.
- Conditioning- the beer is made ready for drinking.
After it is harvested, the grain is soaked in water. This causes it to germinate, during which time an enzyme called “diastase” becomes active and converts the starch in the grain into sugar. The reason that barley is used more than any other grain is that it contains the most diastase- enough in fact to convert not only its own starches, but those of almost any other grains put in with it. It also produces what many consider to be the best flavour. The other grains, called “ adjuncts,” usually include the less expensive cereal grains like wheat, rice and corn.
Once the conversion from starch into sugar has happened, drying the grains with controlled heat in a kiln halts the process. Different types of malt result:
Pale Malt: Lightly roasted, producing the maximum amount of fermentable sugar.
Crystal Malt: Golden brown in colour as a result of a medium roasting, gives a fuller flavour and colour, with less fermentable sugar. It is usually added to pale malt.
Black or Chocolate Malt: Sugars have been caramelized. Very little of it is fermentable, but even a very small amount will result in black coloured beers with a cocoa or chocolate flavour.
Malt is next ground in a mill to produce grist. The grist and any other grains used are then soaked in water at 65 C for about two hours. This process is known as “ mashing.” It takes place in a vessel called a “mash tun.”
The solution that is produced is called “wort” (pronounced “wert”.) Once extraction is complete, the wort is run off into a copper kettle. The remaining grains are then sprayed with water at the same temperature as the soaking water to extract every bit of fermentable sugar possible. This process is called “sparging”.
In the copper kettle, the hops and wort are combined to give the mixture aroma and bitterness, and the whole solution is boiled for approximately two hours.
Before fermentation can take place, the hopped wort has to be cooled to 20 C.
The hopped wort is put into a fermenter and yeast is added. Fermentation starts a couple of hours later. For most ales, it normally lasts up to a week, while for largers it will least twice as long.
As with wine, the fermented beer needs to be prepared by racking, fining, filtering and aging.
When fermentation is completed, the beer needs the chance to rest and mature. Larger is stored as approximately one degree Celsius for several days or weeks. Ale generally has a shorter maturation period (only a week or two) and is held at a slightly higher temperature.
During this time, suspended matter will sink to the bottom of the tank leaving the brew clear. Racking, or moving the beer from one barrel to another without disturbing this sediment, is the next step. To obtain effervescence in beer, a secondary fermentation may be induced once the racking is done. A much more commercial and common technique is to inject the brew with carbon dioxide.
While the resin in the hops is itself a natural preservative, many breweries will also add chemical preservatives and sometimes-artificial colours and flavours. Some beers from France or Belguim don’t have these and if you taste them side-by-side you will instantly notice a difference in depth of flavour.
Traditional draft beer is racked but not filtered. Draft beer, which is not pasteurized, has a much shorter shelf life and should be kept cool at all times.
Most other beers are filtered and pasteurized in order to kill off any beer spoiling bacteria prior to being bottled or canned. This gives the beer a longer shelf life and removes the need for refrigeration. Many beers are also filtered to make them brilliantly clear. However, over filtering can strip a lot of the flavour out of the beer.