Kriek, barrel aged sour beer fermented with cherries. Krieks originated as a variation on another Belgian style of spontaneously fermented beer called Lambic. Lambic producers originated from the area just to the south and southwest of Brussels. It is believed that the region evolved such a tradition of initial open fermentation, then wild or mixed fermentation, in wooden barrels because of the abundance of natural yeast in the air from the many local fruit orchards. Today some breweries which are not in the Lambic region produce Kriek but use other wild or mixed fermentation processes such as a vatted Pale or an Oud Bruin.
Belgium is fairly unique in the respect that using fruit to ferment alongside wort created from grain has been a tradition for hundreds of years. I like to think of it this way. Belgium is a wonderful little country wedged between Germany which is famous for beer, and France for its wine. (There is a reason why many great Belgian beers come corked and caged, just like Champagne.) The Belgians have taken the best inspiration from those around them and put it all together to bring us the most diverse tradition of brewing we know historically. Today of course, we know American craft beer to push all boundaries. But the Belgians have been doing this for hundreds of years!
On to the Boom Island Kriek. This beer pays respect to that Lambic tradition of making beer with cherries. Since we are not producing it in the Lambic region of Belgium however, you will not find the words Lambic (or Gueuze – which means blended Lambic) anywhere on our labels. These are registered terms just like Champagne. Our wort, just like Lambic, was produced by what is called a Turbid Mash. This means during the mash, liquid is drained off, boiled, then returned to the pot to gradually raise the temperature through multiple steps. Our wort is then boiled with old, brown oxidized hops. This is also standard in producing Lambic. The old hops have lost most of their aroma and bitterness potential, but still maintain their preservative qualities. This is important to fight back Lactobacillus. But doesn’t Lactobacillus cause sourness? Lactobacillus could cause some sourness, but Lambic brewers have found the acid it produces lacks the depth and complexity which is found in a barrel aged Lambic.
This brings up a little tangent. A relatively common practice these days here in the US craft beer scene is referred to as a “kettle sour”. This is a technique which does use that very microbe, Lactobacillus, to sour the wort over the course of 24-48 hours before it is boiled. Once the desired ph is achieved, the wort is then boiled to kill off all the bacteria. The remainder of the brew process is a “clean” fermentation and the finished beer can be achieved in a matter of weeks. This allows a brewer to quickly produce a couple of German style beers like Berliner Weisse and Gose. One can find many pleasant and tasty examples of this type of beer on the market.
The Belgian approach however is quite different. As our process continues, we have incorporated a turbid mash and then boiled the wort with oxidized hops. The wort is then cooled and moved to a stainless conical fermenter where it begins fermentation. The top is left open so the now fermenting beer can interact with the ambient air. Next comes the important part. Toward the end of the primary fermentation, the beer is moved into oak wine barrels to rest for more than a year. These recently emptied barrels had been home to sour beer produced by the same method for up to 4 years. The porousness of the wood harbors the litany of microbes which slowly soured the beer in the barrel over the course of at least a year and usually more.
Hand picked tart cherries are added to the barrel and after a year the fermentation kicks back into action. After a couple of months, the sugars from the cherries have all been consumed and the beer is ready to bottle. Fresh yeast and a small amount of fermentable sugar is then added to the flat beer at bottling time. The bottles are corked and caged (the Belgians learned this carbonation technique from the Champagne makers of long ago) and a final fermentation takes place in the sealed bottle creating natural carbonation. This is the short story of how our Kriek is produced
Kriek – 4.8% ABV
Appearance : Light-Red Rose.
Flavor : Slightly tart, nutty and acidic, with a light effervescence and dry cherry halo.