When I first started this solera, I was under the impression that I was special and unique for undertaking this project, but since then I've seen more and more soleras across the internet. Especially for sours, soleras offer an interesting project to undertake.
The basic premise is this: you start a batch of beer, and every year or so you take off a portion of that beer and bottle it, and top off the fermentor with fresh wort or another batch of beer. The portion that you remove can alter the aging properties of the solera - if you take less out, more of the older beer remains, while the inverse is true. This makes it interesting over several years, as the solera builds to be a blend of several years worth of beers. You have the opportunity to taste the bottled portion and decide whether to change the base recipe if the remainder needs more of a certain characteristic.
Traditionally, this was done with sherry, port, balsamic vinegar and others, but it was done in oak casks rather than a glass fermentor. The oak barrels would be lined in a sequence in order of age, and when the oldest (which was the solera) is taken from, it would be filled with the next oldest, and so on. The oak barrels gave the benefit of giving oak character, but also a slow oxidation of the product that gives more nuance, or allows for other microbial growth with oxygenation. This oxygenation can be beneficial and detrimental to a sour beer solera, as it can encourage brettanomyces and deepen the character of the beer, but it also risks introducing too much oxygen wherein acetobacter can take hold and create acetic acid (vinegar) flavors.
I don't have the space or the money for oak barrels, so I ended up creating my solera in a 15 gallon demijohn. Each year I will remove 1/3 - 5 gallons - and top off with the same parent recipe. The original recipe is a traditional turbid mashed lambic base with wheat and pale malt. The solera itself was started on a cake of roeselare supplemented with dregs from 3 fonteinen, cantillon and cuvee renee. To replicate some oak, I've added oak cubes and a half an oak spiral to taste.
At the time of the solera's birthday, it had a pretty noticeable cheerios flavor from THP, which seems to be a recurring problem with most of my sours, so I left it for another few months. 3 months later I've decided to pull it off and put it on a bunch of dry hops.
2 oz each of Citra, Cascade, and Columbus
A nice thick cake of hops!
I'm not sure about the columbus hops - I probably should have stuck with fruity hops instead of thinking like an IPA and trying to balance with some pine. We'll see in a few weeks when I crack the first bottle.
Until then, I've topped the solera back up, and even added a bottle or two of my barleywine to the solera for more malts and some complex sugars, and because why not? A week after topping off with pre-soured beer and some bottles, a small krausen had formed and it was bubbling quite well.
First year on dry hops, and I regret not bottling some straight, but maybe next year.