The beer is a fermented alcoholic drink whose basic ingredients are malted barley (germinated barley), water (beer contains 95 % of it), hop and yeasts.

The production of beer is made of three big steps: malting, mashing en fermentation.

These three steps are divided in many operations. We will particularly describe the following ones :

1. Malting 
2. Mashing 
3. Boiling and hopping 
4. Fermentation
5. Maturation and bottling

 4 - Fermentation

Wort is cooled and added with yeast which transforms the fermentation sugar dissolved in water into alcohol and carbon dioxide. After about eight days, this fermentation is finished.

We distinguish two main types of beer: the bottom fermenting beers, fermented at a law temperature (12 to 15°) with yeast that settles at the bottom of the ale and the top-fermenting beers, fermented at 20-25°C with yeast that rises to the top of the beer after the fermentation.

Bottom yeast gives a smoother, less flavoured and almost neutral taste that makes the taste of the flavour and of the hop stronger. It is the yeast used for classical beers.

Top yeast is energetic yeast that reproduces a lot and that only works well with a temperature higher than 20°C. It produces more ethereal and flavoured beers that seem to be light and easily digestible, even when their density is strong. It is the ideal yeast for specialty beers.

After fermentation is complete, the beer is sat in the fermenter for several weeks at 0°C. The goal of this is to refine the taste, clarify partly the beer and to saturate it with CO2. Top beers only undergo a short cooling.