The challenge of brewing a great lager

ken writes:

Why is it so difficult for most microbreweries to brew a nice lager? Some ideas

  • Microbrewers don’t always like and appreciate lager, so they aren’t motivated to get it right.
  • Microbreweries strive to be flexible and have a wide range of different beers, which means there is some pressure to use labour-saving and simplifying active dry yeast, which doesn’t necessarily give the finest tasting lager.
  • Microbreweries are typically young businesses and capital-constrained businesses, so they cannot afford to tie up tank farm capacity with long vessel residence times. The traditional rule of thumb (according to Wolfgang Kunze) is 1 week of fermenting and 1 week of conditioning for every degree Plato. 24 weeks for a single batch! I don’t think so.
  • Microbreweries tend to be built on the English model, not the German one (because it’s cheaper), so they have difficulty producing a suitable wort.

 

Here are some tips for making a better lager.

  • Start with very good malt. Use a well-modified ale malt and accept that the lager will have a slightly darker colour. This is no big deal. There are superb ale-coloured lagers e.g. Pilsner Urquelle (totally different process, mind you). The higher kilning temperatures of ale malt mean there will be less DMS (dimethylsulphide) precursor in the malt.
  • Pitch massive quantities of yeast. Either grow it up first or pitch twice the recommended amounts. This will give you good attenuation, and will allow you to get a vigorous and timely fermentation at lower temperatures. Proper lager fermentation temperatures are really low: The old-school cold fermentation recommended by Narziß starts at 6˚C and allows the fermentation to rise as high as 8˚C! 12˚C is the absolute highest temperature you should allow. Don’t leave the beer on the yeast longer than you have to. That’s bad for the head, especially with lots of yeast.
  • Use shallow open fermenters. These promote the purging and washing away of volatile sulphur aromas as well as the rapid settling of yeast. (Shallow fermenters also tend to reduce attenuation so plan for this in the mashing profile and with yeast choice.
  • Use measures to promote the coagulation and precipitation of protein in the brewhouse, for example ensuring boil pH is 5.1-5.2 (suggested by Kunze), boiling without hops initially, using tannic acid additions to coagulate proteins which aren’t  otherwise coagulated by heat, using Irish moss or other kettle finings, and treating kettle wort with gypsum again. Run the wort into the whirlpool gently to avoid breaking up large flocs. Allow a longer wait in the whirlpool to give more settling time and to allow some hot wort oxidation will also promote clarity in the final product.
  • Use traditional hop varieties. It should look like beer, smell like beer, and above all taste like beer.
  • Boil away at least 10% evaporation.

How much actual lagering time the lager needs depends on how successful the measures to promote clarity and aroma in the brewhouse. The traditional purpose of lagering beer, according to De Clerck, is mostly clarification, carbonation and the removal of green beer aromas. Carbonation is taken care of in most microbreweries by forced carbonation with CO2. Clarification can be sped up by filtering and/or fining. This is what used to take so long because the protein-polyphenol complexes that cause chill haze are extremely small and settle extremely slowly. Tannic acid and colloidal silica treatments can encourage their precipitation, agglomeration and settling. Shallow tanks speed settling time because there is less distance for particles to fall. The removal of green beer flavour is mostly accelerated by doing as much as possible to avoid the sulphurous flavours in the first place. Look at the choice of malt and the choice of yeast strain and don’t ferment the beer under top pressure.

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