Top fermentation, bottom fermentation?

TOP FERMENTATION OR BOTTOM FERMENTATION BEERS?

Over a glass of beer, discussions sometimes arise about what top fermentation or bottom fermentation beers are. According to some, the terms top fermentation beer and bottom fermentation beer are determined by the temperature at which the beer ferments in the tank. And although it’s correct that bottom fermentation beers ferment at a lower temperature than top fermentation beers, that’s not the full explanation.

Top fermentation beers, like our Charles Quint, Tongerlo and Mystic assortment, ferment between five and six days at a relatively high temperature of 18 to 22 °C. After this process, the yeast floats up and forms a thick layer on the beer. That explains the name top fermentation beer.

The opposite goes for bottom fermentation beers, like our Primus. After a fermentation period of eight to ten days at a lower temperature of 10 to 12 °C, the yeast sinks and stays on the bottom of the fermentation tank. That’s why these beers are called bottom fermentation beers.

The yeast floating to the top or sinking to the bottom results from the yeast strain that is used, not the temperature. The yeast strain also plays an important role in determining the beer’s aroma.