Februrary 2nd - Brewing Lambic

February 2nd – Brewing lambic

We brewed another 10 gallons of lambic today and also packaged the molasses porter from last time. The porter is fairly sweet (which is what we wanted) and has a subtle molasses flavor. It’s just enough to taste it but not so much that it overwhelms the other flavors. It’s still a little young, but it has some roastiness and a nice bitter chocolate quality. In addition to the molasses, there’s a caramel sweetness as well. It’s got a big rich, round mouthfeel and should be good in the cooler weather.

We hadn’t brewed lambic in a while (maybe four months or so). Our stocks of it were down to about 80 gallons which are all between 4 months and 4 years old. We had picked up the production of these a couple of years ago once we had a chance to taste the first ones and decide if it was all worth it. Sour beers are getting more popular and it’s good to see that more and more breweries are making them.

Our “lambic” is modeled on the real ones from the Senne Valley in Belgium. The grain bill is fairly simple: 2/3 pilsner malt and 1/3 flaked, unmalted wheat. Hops are used for the aseptic properties but not for their bittering qualities and brewing lambics requires the use of old hops. Hops are best at a couple of years old, but you don’t want them cheesy or moldy smelling. Ideally, they should be totally dry and reminiscent of dry hay in aroma. The traditional mash for lambics is a turbid mash which is a complicated process and is sort of similar to a decoction mash, except that in a turbid mash, you pull the liquid from the mash and then boil it and add it back in to raise the temperature. In a decoction mash, you pull the thickest part of the mash out and boil it. The enzymes that convert starch to sugar are water soluble and are in the water that you boil in a turbid mash and that essentially denatures the enzymes and deactivates them. Unlike most other types of brewing, you actually want unconverted starch in a lambic base because it will be consumed by one of the types of wild yeast down the road.

We don’t use a traditional turbid mash, but do a step mash instead. We mash in at about 122 for a 30 minutes protein rest to help break down some of the excess protein in the flaked wheat. Then we raise it up to about 156-160 in order to get a wort high in dextrins. Dextrins are a complex sugar that aren’t digestible by standard brewing yeast, but can be broken down by wild yeasts. The idea is to make a wort that has some easily fermentable sugars for the brewing yeast, but also has a fair amount of starch and complex sugars for the wild yeasts and bacteria that grow later in the process.

This time we ended up with a stuck mash which made for a long brewing day, but we made our way through it and ended up with 10 gallons of cloudy wort (cloudy than normal, but these beers will sit for about 2 years before being bottled). We added standard brewing yeast and will that work for about 1-2 weeks before we rack it into carboys and then add the wild yeasts and bacteria. We’ve gotten some Belgian Sour blend from White Labs and a tube of pure Brettanomyces lambicus. The major souring bugs in lambics are lactobacillus or pediococcus, both of which are bacteria and produce lactic acid, and brettanomyces, which is a wild yeast which gives some sourness as well as the characteristic barnyard and “funk” aromas to these beers. Lactobacillus can take several months to really grow, but Brett can take 6-12 months. The Brett aromas and complexity will grow over several years and the beer will become increasingly dry and steely.

The problem in brewing with all of these bugs is that they’re unpredictable. There’s no guarantee that all of them will grow and no way to tell which “bug” will become the dominant one. Each 5 gallons carboy is its own ecosystem and each one will taste slightly different, even if the base beer and bugs were the same. As a result, blending is a critical part of the process. We normally blend beers to roughly 25% one year old, 50% two year old, and 25% three and four year old. We can use as many as ten lots to make a single batch. Since having different lots of beers seems to add complexity to a blend, and since most of the bugs are available as blends and as single species, we’ve gotten in a habit of adding different bugs to different carboys to create as wide a variety of underlying beers as possible (even though they all use the same grain bill and old hops). Oftentimes, we combine leftover partial lots together increasing the complexity of the individual carboys and have found that the more lots you have, the better chance you have of making a successful blend. Currently we have a little more than 20 carboys of different sizes sitting around. Our blends are normally about 8 gallons, because that’s the largest bucket we have for blending and it gives a decent size batch.

Each batch we’ve blended has been different but there is a somewhat of a “house” style that we’re developing. Our beers are not as tart and sour as some of the traditional lambic houses, like Cantillon, but at our best, the beers have the right taste and characteristic aromas. I would like then a little tarter, but they’re tart enough to be refreshing and are generally equivalent in acidity to an average white wine. We’re working on getting the carbonation level high enough to really emulate the best commercial examples and aren’t quite there yet.

We don’t have any fruit batches going right now but will be investing in raspberries in a few months to make some framboise for the fall. Normally the beers need to sit for 4-8 months with fruit before being bottled. It’s best to let the beers age at least a year before adding fruit, since they still need the underlying complexity. We’ve done both raspberries and cherries, but so far the raspberry is the clear winner to me.

So we brewed ten gallons and built the stocks back up, but this beer will likely sit for at least 2 years before it’s bottled. We are planning on blending another lot in the next month or so, because we’ve built up enough stock that we should be able to bottled 2-3 batches a year without depleting our stocks too much. The main issue is making sure you keep enough of the beer back to get sufficient stocks of three year for blending. Strangely, the older lots, while incredibly complex, aren’t very good on their own. By 3-4 years, the beers are very austere and bone dry. They get a kind of steeliness to them as well. They add great depth of character to a blend but need younger beer as well to soften them. We had debated bottling some straight three year old but, on tasting it, realized it wouldn’t be the best thing to drink on its own.