Top-cropping yeast, also known as Saccharomyces Cerevisiae, provides the counterpart to bottom fermented beers. Top-cropping yeast prefers higher temperatures, between 15 and 25 degrees celsius and is mostly active in the top of the kettle. Top fermented beers require less conditioning time and often have fuller, fruitier and floral aroma’s. Examples of top fermented beers include IPA’s, Weizen beers and Porters.
Examples of beers are Lagunitas IPA, Jopen Mooie Nel, Erdinger Hefeweizen and Kompaan Bloedbroeder.
The use of these yeast strains means the brewer has less control during the process. And yet, more and more beers are being brewed the old-fashioned way. These beers are called spontaneous fermentation beers. These Lambic beers mostly derive from the Zenne Valley, the area South West of Brussels. To produce this beer, the wort is pumped into what is known as “cooling vessels”. In the cooling vessels - a type of large bath tub - wild yeast that might be drifting in the air is given the opportunity to settle into the sugar-rich wort. Shortly afterwards, the wort is put into wooden barrels where the yeast is given plenty of time to work it’s magic.
These Lambic beers form the basis for Geuzes. This is the result of a blend of Lambic beers of varying ages. It’s a true art to create a great Geuze. The blenders are known as Geuze-stekers and are held in high esteem in the beer world. Geuzes are sour beers that you can sometimes keep for decades and which age beautifully like a good wine.
Examples of beers are Mort Subite Gueuze, Boon Geuze Mariage Parfait and the Oud Beersel Oude Geuze.