At Brasserie du Bocq, there are five fermenters for a total capacity of 220.000 litres, or 10 brews. The yeast is pitched into the wort during transfer from the kettle to the fermenters.

Fermentation takes 4 to 5 days. The yeast multiplies by four and this transformation leads to a natural increase of the temperature that will rise from 19°C to 28°C.

The sugars of the wort are transformed into alcolhol and carbon dioxide (CO2).

At the end of fermentation, the beer is cooled to a temperature of 4°C by circulating iced water in the serpentines at the bottom of the fermenters, before being pumped out of fermentation vessel.

The yeast is recovered after fermentation and used again for the next fermentations. The taste and aroma are formed , the wort changed into beer, but into a beer not yet suitable for consumption.