I must apologise about my poor blogging output over the past year or so, but there have been some big changes behind the scenes which have got in the way of my blogging and brewing…but I’ve not been completely inactive.
As my regular readers may recall, I’ve done some test brews using a newer “lagering” method in which lager-style beers are produced using lager yeasts fermented at ale temperatures (post 1, 2, 3 and 4). Motivated by these successes, I’ve brewed over a dozen lagers using this method in order to refine this process, with my last two batches produced using the same refined method. The first of these was a German-style pilsner; specifically the “Myburger” Bitburger clone from “Brewing Classic Style“. Not only was it delicious, but I had trouble telling it apart in side-by-side tastings from its commercial cousin. The second beer was a doppelbock, and was everything I’d expect from the style. The take-home lesson from those two brews is that you can make very good “lagers”, true to style, without the need for prolonged cold fermentation. Indeed, the Pilsner was 2 weeks grain-to-glass, and a month for the doppelbock.
My method is pretty straight forward, and does not differ much from the one worked out by Brulosophy.
Preparing the yeast: The single most important part of the process is a large pitch of very healthy yeast. A good pitch of healthy yeast, into an appropriately prepared wort, will provide the clean fermentation your lager requires. Get the yeast part right and the rest will fall into place.
For liquid yeast:A few days in advance prepare a large starter of yeast – for an average gravity lager you will want 1.5 to 2 million cells/ml/degree plato (AKA strong ale-to-conventional lager pitch rates). For high gravity lagers you will want 2 to 2.5 million/ml/degree plato. Your goal with this starter is to maximise yeast numbers and yeast health – use plenty of yeast nutrient, and be sure to stir vigorously enough to ensure maximum oxygenation. These starters are large, so you are going to want to decant the spent wort prior to pitching your yeast.
For repitched yeast: Simply having a lot of yeast is not sufficient – you also need it to be healthy. As such, if repitching yeast from a previous brew, make sure you run it through a revitalization starter – e.g. add the amount of yeast you intend to pitch to a 1 to 1.5L/1.040 gravity starter, made with a good dose of yeast nutrient and stirred to give a high level of oxygenation. This will not produce more yeast, but will ensure that the yeast you pitch are at peak health. Again, I would suggest decanting these starters, although the smaller volume make this less critical than when preparing a starter from a tube/smackpack/yeast bank.
For dry yeast: Dry yeast tends to be in relatively good shape, so long as it isn’t too old or was stored improperly. Again, you want a lot of yeast, so for an average-gravity lager you will likely want to use 2 sachets of yeast; 3-4 sachets for a high-gravity lager. Be sure to rehydrate the yeast properly, in order to ensure the maximum number of active yeast and the best yeast health.
Preparing the beer: Nothing special needs to be done here, and no modifications need to be done to the recipe; simply brew the wort to the best of your abilities. At the end of the boil, cool the beer as cold as you can reasonably get it – ideally to 14-16C, although anything below 20C is acceptable.
Transfer the beer to a semi-sealed fermenter such as a carboy + blowoff tube. You want to avoid “open” bucket-style fermenters as these can enhance ester formation and may lead to a loss of the modest sulphur character present in most lagers. When you transfer the beer be sure to transfer a small amount of trub as this can also help to suppress both ester and fusel alcohol production. Finally, oxygenate well and pitch your yeast.
Primary Fermentation: Because we’ve front-loaded our brewing process with several methods to provide a clean fermentation, we can get away with a fair bit on the fermentation end. A broken temperature controller led to an accidental “lager” fermentation at 25C (77F), and the beer still turned out fine. That said, some control over fermentation temperature is simple insurance, and at a minimum, should speed the time the beer needs to age before it is keg ready. I’ve had the best results (or, at least, keggable beer the quickest) when I held the fermentation temperature to between 14 and 17C (57 to 62C) for the first 3 to 4 days; this is when most ester formation occurs, so by keeping things cool we can further minimise ester production. At this point I raise my fermentation temperature to 20-21C (68-70F), and hold that temperature until primary fermentation is done (~2 weeks). These higher temperatures ensure full attenuation and cleanup of off-flavours such as diacetyl and acetaldehyde.
Secondary Fermentation & Packaging: Secondary fermentation is not required for average-gravity lagers, but I’ve found that transferring higher-gravity lagers to a carboy with airlock for an additional 2-4 weeks can greatly help their character and get them closer to style. Once ready for packaging, crash-cool the beer and transfer to the keg/bottle (add gelatin at this time, if you use it). Carb as per usual and serve – all of my test batches but the one brewed with S-23 was fantastic on the first serve, although in about half of cases I’ve noticed some modest improvement over the first week or so in the keg.
And that’s it – pitch lots of healthy yeast, maintain some level of control over your fermentation, and you should end up with a nice lager…in two (or so) weeks.