There are a number of criteria for beer classification – colour, appearance, grade, strength, technology or ingredients used. Some of the most important are described below.
Confusion of beer grade with alcohol percentage is a common error. So, the “eleven grade” beer by no means contains 11% of alcohol, the “twelve grade” does not include 12% of alcohol etc. Such beers would be extremely strong.
Confusion of beer grade with alcohol percentage is a common error. So, the “eleven grade” beer by no means contains 11% of alcohol, the “twelve grade” does not include 12% of alcohol etc. Such beers would be extremely strong. The grade in fact identifies the percentage of original ingredients in wort (OWE = original wort extract, expressed in percent) before fermentation. For example, a 10° beer grade means that 10kg of wort contains (diluted) 1kg of solids (especially sugars) from the input ingredients. However, alcohol content is proportional to the quantity of fermentable sugars (especially glucose and maltose) in the wort, and so the beer grade is related to beer strength, although not proportionally. For example, pilsner “twelve” surprisingly only contains 4.4% of alcohol. The reason is that Plzeň brewers do not let the whole extract ferment (transform to alcohol). The non-fermented residues then add the typical full taste to the beer (see the chapter on brewing above).
Beer grading has been abandoned recently (for commercial reasons) and now a newly introduced standard is used.
Tap beer – corresponding to the original grades 7 to 10.99%
Lager – corresponding to the original grades 11 to 12.99%
Special beer – corresponding to the original grades 13% and up
There is bottom (lagers) and top (ales, wheat beer, stouts) fermentation. The bottom fermentation uses yeast species Saccharomyces cerevisiae subsp. uvarum, “working” at up to 15°C (the optimum temperature is 8 to 14°C) for seven to twelve days. This type of fermentation is called “bottom” for the reason that the yeasts mainly accumulate in the bottom part of the column. The top fermentation takes place at temperatures of 15 to 25°C (below 15°C the yeast activity is reduced and below 10°C it stops completely) for two to eight days. In the course of the fermentation the yeasts of the Saccharomyces cerevisiae species, cerevisiae subspecies, develop rich foam on the wort surface, called blanket. Hence the process name “top fermentation”. The least known process is “spontaneous” fermentation, mainly used in France and Belgium. This production is not significant from an industrial point of view, but the result is very special for rare beer tastes.