Every variety of yeast is unique and has a great influence on the final flavour of the beer. Hence the Trappist yeast is cultured and harvested in the brewery with the greatest of care. It also largely ensures the subtle, complex flavour of the beers.
Yeast is a single-celled vegetable micro-organism that converts the sugars into alcohol and carbon dioxide. The Westmalle yeast comes from the family of Saccharomyces Cerevisiae and ensures ‘top fermentation’. This form of fermentation thrives best at between 15° and 25° Celsius and forms a thick layer on top of the brew. Hence the name ‘top fermentation’.
This type of yeast is very active and fast-acting. The yeast cells propagate by budding from the parent cell in an exponential way. They can be used again and again in new brews for months. When the activity becomes too low it is necessary to rejuvenate the yeast culture. New brewing yeast is then created from one healthy yeast cell. This ensures that the typical yeast culture of Westmalle is never lost.
