Following up on our last article on off-flavors caused by yeast, we wanted to talk about Sour Beer. Yeast can and will cause many negative flavors. And while wild yeasts many not be great for your next Scotch Ale or East Coast IPA, there are many positive flavors that can come from some controlled wild yeast fermentations – especially sour flavors.
In the early traditions of brewing it was tough to find a beer without a mild sour flavor, so when pasteurization caught on in 1864, it was preferred and took off dramatically. Who wouldn’t want a crisp clean beer without sour flavors? When lots of beers changed during this period, many folks lost interest in the long cultivated brewing practices of Bruins, Goses, and Berliner Weisses. But just within the last few years sour beer has hit a new stride, not only giving new breweries a place to start but also giving many credentialed sour beer breweries a revival.
There are a large array of sour beers that we can go into, but for this article we’ll be concentrating on Lambics. Named after the Flemish city of Lembeek, Lambics got their main start in Brussels, Belgium. Sour…sweet…funky…fruity… the list of flavors can go on and on. And guess what? The brewing process is even more complicated than the plethora of adjectives one could use to describe a Lambic.
Let’s first start with the malt bill. Where many breweries start with a blend of malted barleys, Lambic brewers start with a grist of only about 60 to 70% barley in combination with 30 to 40% raw wheat. We’re talking unmalted (ungerminated) straight up ground wheat. This is an extreme amount even compared to many Wheat Ales, which use malted wheat to drive a higher alcohol percentage. Using the unmalted wheat in a Lambic helps not only keep the wheat flavors strong, but helps keep the gravity down as well to make for easier drinking and a better control for wild yeasts.
During the boil brewers add a collection of aged hops, used more so for their antimicrobial effects than for their flavors. Many of these aged hops have a low acid content, meaning little bitterness and citrusness, and flavors ranging from oxidation (wet cardboard flavor) to the large assortment of funk flavor found in things like cheese. In the early traditions of Lambic brewing, brewers would use fresh, high acid hops. Those varieties have since died off in most Lambics.
Once the wort is boiled and completed, it is cooled in devices unique only to Lambic brewing called Koelschips (or Coolships in English), large flat shallow trays made of metal. Windows or special vents in the brewery are opened and the beer is then exposed to the elements, letting wild yeasts including Sacchromyces, Brettanomyces, Pediococcus, Lactobacillus, and Enterobacter explore the sugary liquid and inoculate themselves. It is these yeasts and bacteria that are responsible for the variety of flavors that come through in Lambic. Spiders may not be a positive thing to see in many breweries, but in Lambic breweries they are encouraged! (Right now we know you’re like “Whattt???”) Spiders help trap and consume many insects that are attracted by the large vats of sugary liquid. If it weren’t for these guys you would have a bunch of bugs in your beer!
Once the wort is cooled it is then transferred to timber casks, preferably of oak or cedar. Many of these casks once belonged to Spanish or Portuguese sherry and port brewers. The Lambic ages in these casks for at least one year or greater. During this time the beer forms a layer of growth over the top called el velo de flor, commonly referred to in English as the pellicle. This biofilm consists primarily of entwined proteins, sugars, and living and dead cells somewhat like plaque forming on top of your teeth. This layer has been said to help reduce oxidation and ensure that the organisms in the beer are functioning to their fullest extent. The beer is then racked and bottled.
Many brewers will also save multiple years of Lambics and blend them. Older varieties will have a harsh and very acidic property so the young varieties are added to mellow and smooth out the acrid flavors of the old lambics. This style of beer is called Gueuze. Other versions of Lambics include fruit, with the most popular being Kreik (sour cherry), Framboise (raspberry), Cassis (black currant), and Peche (peach). Modern examples are usually more sweet and traditional examples are generally more dry.
The brewing process of Lambics has been called one of the most complex in the whole world. So why not serve it properly to respect all the work put in? Serving temp should be around 40F to 55F with cooler temperatures lending themselves best to fruited lambics, and warmer temperatures lending themselves best to unblended Lambics or Gueuze. Lambics are traditionally served in in slender tulips, stange glasses (think Tom Collins glass), or Champagne flutes. A large foamy head is preferable during the pour to release all the brilliant aromas that Lambics can generate. Don’t pour the last quarter inch out though! Leave the sediment in the bottom unless you want a hefty dose of Vitamin B12. Yeast tends to gather at the bottom of most Lambic bottles and can throw off the flavor if poured into your glass.
Ask any one of our talented beer specialists at 8 Degrees Plato about their favorite Lambics and they’ll be happy to point you in the right direction. We carry many varieties like Boon, Lindeman’s, De Troch, Giradin, and if you’re lucky sometimes Cantillon and Drei Fonteinen.
And as always, cheers to beer!
Special note for those who read all the way to the bottom: You’re Awesome! Next time you’re in tell Zach that Lambics are cool and he’ll happily take 10% off of your first Lambic purchase.