Let's get down with Sours
The tart, delicious and unique taste of this beer style just can't be beat if you are a sour fanatic. The sourness comes from our perceived taste of acidity, which in most beer styles is considered an off flavor. Most beers have some level of acidity to them (with pH levels between 4.1-4.5) with sours ringing in between 3.1-3.7. Traditionally, beer was fermented using wild yeasts which caused it to have a rather sour and funky taste. Science and advances in technology allowed brewers to isolate yeast strains and provided them with the ability to create beers without the tang and sourness caused by wild yeasts. You can still find sour beers and for those of us who enjoy them, that's a wonderful thing. Traditional sour styles include lambics, gose, Flemish red, oud bruin and berliner weisse. The sour and funky tastes of the beers in this style category come from the types of yeast being used as well as bacteria such as brettanomyces, pedioccocus, lactobacillus and acetobacter.
Sour style beers originally were fermented in barrels and would take a relatively long time to mature. Styles such as gueuze (an unfruited sparkling form of lambic) is created by blending one or more lambics of different ages together in a bottle. The younger lambic provides sugars which are used to help the beer ferment in the bottle. Barrel aged sours develop an array of flavors over time and many are complex and unique. A more recent souring method, kettle souring, decreases the time it takes to sour a beer. This method starts out much like brewing any other beer style. A brewer creates a recipe, gathers ingredients, mashes the grains and creates wort. The wort then must be made more acidic (compared to other styles) so brewers usually use an agent such as malic or lactic acid to accomplish that goal. Now this is the part where things get sour. Literally. Brewers pitch a Lactobacillus culture (yogurt is used by some breweries) and then the inoculated wort is left to sour. Once the desired sourness is reached the wort is transferred to the boil kettle and normal boiling and fermentation takes place.
While both barrel and kettle sours produce sour style beers they often taste a bit different. When in the barrel the beer picks up other flavors and develops in a more complex way. Kettle souring gets to the finished product much faster but it does not have the depth of many barrel aged sours. Both styles are delicious in their own ways and if you are a sour fan you get the best of both worlds. To get a hands on experience buy a barrel aged sour style beer and a kettle soured one and try them side by side. What flavors do you notice in each? How are they similar? How are they different? Do you prefer one over the other?
As always have fun and remember to explore craft culture daily!