Friday, 14 June 2019 —
The monks of Westvleteren apply the traditional infusion brew method, only using natural ingredients. First of all warm water and scraped barley malt are mixed together. The mash is heated until the present starch is converted to sugars. The sediment forms a layer of filter. The bright filtrate that is obtained is called wort. Next the wort is heated and hops are added after which the boiled wort is cooled down.
In the early 70s problems with the quality of the beer produced at Saint-Sixtus occasionally occurred. The staff magazine made mention of the withdrawal of sold beer. Most likely insufficient awareness of the importance of hygienic methods during the brewing process and different kind of infections resulting from it were cause of these quality problems.
Therefore the monks of the Saint-Sixtus Abbey summoned the aid of Brother Thomas, brewer of Westmalle Abbey. He initially informed them only some small adjustments were needed. Eventually the cooperation between the monks of Westvleteren and Brother Thomas ended in a thorough re-engineering of the brewing and fermentation process.
A new brewing method Until 1976 the Saint-Sixtus Abbey used a coolship and the wort was exposed to the open air and its micro-organisms. In 1976 the coolship was replaced by a closed wort cooler and a yeast room with six open yeast barrels, having the possibility of being separately cooled, were built. The same year a laboratory was built allowing the production’s quality to be monitored accurately.
On the basis of the new method of preparation the first test brews were produced shortly afterwards. In 1978 a switch to this method was made for good. The Abbey of Saint-Sixtus abandoned the sweet-and-sour beer recipe and laid the essential foundation of the Trappist of Westvleteren’s actual high quality.
Fermentation, lagering, bottling and secondary fermentation in the bottle Since the open stainless steel yeast barrels came into operation liquid yeast from the Trappist brewery of Westmalle was added to the wort.
The fermentation itself takes about 7 days. During this period all aspects of the fermentation process (temperature, degree of acidity and fermentation…) are accurately monitored.
Subsequently the beer is pumped over for the second fermentation. During this second fermentation the remaining sugars ferment. The beer becomes clearer and the taste refines. The maturation process takes 5 to 12 weeks, depending on the type of beer.
After the final control the beer is judged on brightness, degree of carbon dioxide, aroma and taste, and is bottled unfiltered. Fresh yeast and sugars are added for the fermentation in the bottle, which causes a natural saturation with carbon dioxide.
The refermentation in the bottle takes place in a heated warehouse and requires 2 weeks. The unfiltered, non-pasteurised beer remains some time in the saturation room before it is released for sale.