WHAT IS A SOUR BEER

Sour beers or Sour Ales are one of the oldest types of beer, unknown to most but making a strong comeback.

Sour beers are mostly brewed through spontaneous yeast fermentation: the wort is left to cool for a whole night in large tanks called ‘coolships’, located in the attic of the brewery, before being put into wooden barrels. The yeasts and bacteria naturally present in the air settle in the wort and in a few days fermentation starts.

The spontaneously fermented beer par excellence is Lambic, which is only brewed during the winter months in Belgium in the area stretching from Brussels to Pajottenland, along the valley of the river Senne

However, spontaneous fermentations are not the only existing style of sour beer; there are others that differ in terms of origin, production method or type of yeast and bacteria.

In the last decade, it has been possible, thanks to technology, to isolate wild yeasts in vitro for controlled inoculation. In this case, one can no longer speak of spontaneous fermentation but will speak of beers inoculated with yeasts or bacteria.