Quezi

Photo by Jason Rogers - CC-BY

Ale and lager are both types of beer. There are many subtle variations in the way beer is made, but the basic process is this:

• Barley grains are soaked, heated and turned in a process of controlled germination, to convert much of their starch to sugar.
• The grains are kiln-heated to stop the germination and to impart a flavor by roasting them.
• The grains are crushed and mixed with hot water to dissolve the sugar. The solution, called wort, is extracted.
• The wort is boiled with hops (a fruit), and sometimes with hop flowers too.
• The hopped wort is poured into fermentation tanks.
• Yeast is added. Yeast is a fungus which turns the sugar into alcohol and carbon dioxide.
• The fermented beer is poured off into conditioning tanks for a few days while its flavor develops.

Ales and lagers use different species of yeast.

Ales use Saccharomyces cervisiae in a process known as a “top fermentation”, which works best at temperatures from 15 to 25ºC (59 to 77 degrees fahrenheit). This is a quick process which can take as little as a week, and produces an “assertive and robust” taste.

Lagers use Saccharomyces Uvarum in a process known as “bottom fermentation”, which works best at cooler temperatures. Traditionally it was fermented from 5 to 10ºC (44 to 50ºF) in a process which may take several months, but nowadays temperatures up to 12ºC or even as much as 18ºC may be used (54ºF or 64ºF) for shorter fermentation time. This produces a smooth, clean and subtle taste.

Variations include the addition of sugar, the use of different strains of the yeasts, different degrees of roasting, the inclusion of some unmalted barley, the use of different grains including wheat, or the addition of some corn, rye or even rice to the barley. Some makers add flavors at the end of the brewing process.

Ale is traditionally served at “cellar temperature”, while lager is best at “fridge temperature”.

The following kinds of beer are all types of ale:

• Bitter, which is popular in English pubs, is a golden-brown ale: hoppy, not too dry, and … bitter
• Stout is a heavy, dark, rich-tasting ale, which includes some roasted unmalted barley in the process
• Porter is a heavy, bitter ale—dark but not too malty

The German word “lagerung” means storage. It’s likely that the making of lager was discovered when fermenting beer was stored in a cooler place such as a cellar or even in an ice cave over winter, enabling the slow fermentation process to occur.

Ales have been brewed for thousands of years. Even the Sumerians brewed something we would recognise as ale. Lagers, on the other hand, have only been known for a few hundred years.

For more information:

• “Making Beer“, by the Campaign for Real Ale
• The Beer FAQ