Bohemian Wrenbury

It’s been a few weeks since we last made beer, partly because we have three in barrels ready for drinking, and partly because Andy and I have been away. But a brewer’s work is never done…

…so yesterday we brewed again. And this time it was something very new – lager. Yes, with the prospect of warmer days coming we’re planning ahead so we have something cold and refreshing to offer guests.

So what is it that makes a lager different to an ale?

1. It is made with different yeast. Lager yeast is “bottom fermenting yeast” because the yeast cells do not clump together and float to the surface in a thick crust like ale yeast.
2. Lager yeast ferments at a much lower temperature (10-12C rather than 18-20C).
3. A lager is “lagered” (the German word for “store”), which means once it is fermented it is stored for a number of weeks at a very low temperature (4-6C)

Obviously there are other differences with lagers, but these are recipe-based, i.e. lagers are generally very light in colour and highly carbonated. But not necessarily. The three things above are the main things that define a lager.

Items 1 and 3 on the list are pretty straightforward changes to our brewing process. But item 2 (fermenting at 10-12C) has presented us with some challenges and, err, a retail opportunity. Essentially we’ve needed to crack the issue of temperature control. For ales it has always worked OK to ferment our beers in a cool room in the house (the utility room is generally about 19C). I tend to warm them up towards the end of fermentation by moving the fermenter onto the underfloor heating in the dining room.

But that approach is no good for a lager, and even if the garage is down at about 12C at the moment the temperature fluctuates too much between day and night. So I have built a temperature controller for the beer fridge (hence the retail opportunity).

The fermenter is in the fridge with a temperature probe attached to it by blu-tak. This goes to the temperature controller which turns on and off the fridge (and optionally a heating element too, but we don’t have one at the moment) in order to maintain the required temperature (11C in this case). It’ll be great because as I want to ramp up the temperature towards the end of fermentation I can just set it on the controller. By the way I said “built” earlier because the controller came without all the necessary wiring and case, so I had to do that bit.

So what lager did we make? Well this leads to the strange blog post title. Bohemian Pilsner is essentially Czech lager, along the lines of Budweiser Budvar and Pilsner Urquell. It’s a rich malty lager with a spicy floral bouquet from Saaz hops.

It’ll be a long time before I can report back on what it’s like, but I’ll keep you posted on how the brewing part goes.