Top fermentation refermented in the bottle (oak barrels)
Most Belgian special beers ferment during 5 to 6 days at quite a high temperature (between 18°C and 22°C). The yeast then rises to the top of the tank and forms a thick layer on the beer. Because of the rising yeast, these beers are known as ‘top fermented’ or ‘high fermented beers’. It is not the temperature that makes the yeast rise, this is due to the used type of yeast culture. The yeast culture also plays an important role in determining the beer’s aroma.
This combination is used for Bush Prestige beer from the Dubuisson Brewery. This Belgian beer is not stored in the traditional stainless steel barrels but ripens in oak barrels during 6 months.
Refermentation of beer
A small amount of pure yeast culture is added to the beer just before bottling. The yeast can now turn the remaining sugars into alcohol and carbon dioxide. Sometimes liquid sugar is added to feed the yeast. After that the beer can referment in warm chambers for several weeks. The refermentation proceeds in the bottle and gives the beer a more delicate aroma and a typical taste. The beer evolves and will become more complex. During the maturation process, the yeast falls to the bottom of the bottle. So when you come to pour it, you can either pour out the yeast into your glass or leave it in the bottle depending on your preference.