Revision as of 03:15, 23 February 2009

This second article about German Brewing in the later half of the 19th century covers the fermentation process and select beer styles as outlined in "Chemie fuer Laien" (1860). The first article (German Brewing between 1850 and 1900 : Malting and Wort Production) covered the brewing process from steeping the malt to cooling the wort.

Fermentation

The production of a good beer depends very much on the chemical process which we call fermentation. As a result the brewer has to give it his utmost attention. If it runs badly the beer will be bad even if all other processes ran well and were controlled with care. But if it runs well it is possible to compensate for small mistakes made up to this point. Except if the wort got sour because in this case the 2nd fermentation already happened before the 1st one started.

The beer fermentation is divided into two groups: top fermentation and bottom fermentation. Both types convert the sugar into alcohol and carbonic acid. But in beer this conversion should not be run until completion because one would like to have not only alcohol but also substance in the beer. The alcohol makes the beer invigorating, the carbonic acid gives it the refreshing taste, the unconverted sugar makes it nutritious and the hops give it the spice. The fermentation should not destroy these properties nor should it affect them negatively and thats why it is so important to control it well. Today we know that there are fermentable and unfermentable carbohydrates in the wort and that the yeast can consume only the fermentable ones anyway

Besides the mentioned primary purpose should the fermentation facilitate the precipitation of a substantial amount of the protein. The more it is removed the more stable the beer will be. But the beer should never become void of any fermentation substrate, because unlike vine it is not a fully fermented beverage. If it would become that it would stop being pleasantly drinkable. The carbon dioxide, which is formed through fermentation, is substantial condition for the pleasant taste. It is not present in vine since there the fermentation is complete and all the carbon dioxide has escaped. It sounds as if the author was not aware that carbon dioxide is trapped in the beer if the vessel is closed and that it can retain carbonation even after complete fermentation. To prevent such a staling of the beer the beer needs to retain enough fermentation substrate such that it can slowly ferment throughout its existence. This is the same with the Champagne.