An Oktoberfest is a traditional German lager, brewed in March (hence the style name of Märzen) and conditioned for long periods of time to serve up in time for October. In the past ‘Märzen’ referred to a specific strength of beer rather than a style and the German amber lager version was first served at Oktoberfest in 1872, right up until 1990 when the golden Festbier was introduced.
The trick to brewing a great Märzen is patience and quality ingredients. If you have access to them then you should be using authentic German malts. High quality Pilsner and Munich malts should form the basis of your recipe.
Traditonally, once the beers had been brewed they were fermented in cold cellars for anywhere from six to eight months and would be brought out in time for the Oktoberfest festival, a huge party that started in 1810 to celebrate a royal wedding.
In terms of recipe development you are looking for a strong malt character so you should base most of your gain bill on malts such as Pilsner, Munich and Vienna to get that bready, toasty character that is true to style. With hops you should again stick with German varieties were possible, such as Tettnanger, Hersbrucker or Hallertauer Mittelfrueh.
Mash at around 67°C (152°F) for 60 minutes. If you want to brew as authentically as possible then you will need to attempt a decoction mash though for most modern malts this isn’t really required.
For yeasts, use a Bavarian lager yeast strain such as M76. Lager yeasts ferment at colder temperatures than ale yeasts so some kind of temperature control will be required. With M76 for example, it ferments best between 8-14°C (45-57°F).
With a lager fermentation you will get good results if you chill your wort down to 7°C (45°F) before pitching the yeast and then fermenting for 10-14 days at this temperature. At this point you can then drop the temperature to around 1°C (or 34°F) and hold at that temperature for anywhere between 6 weeks to 8 months.
Boil Gravity: 1.053
3.7 kg (8 lbs) Pilsner
1.5 kg (3.3 lbs) Light Crystal
1.0 kg (2.2 lbs) German Munich
0.15 kg (0.33 lbs) CaraVienne
0.1 kg (0.22 lbs) Acidulated Malt
15g (0.53 oz) Magnum @ 60 mins
10g Hallertauer Hersbrucker (0.35 oz) @ 10 mins
10g Hallertauer Hersbrucker (0.35 oz) @ 0 mins
Chill your wort to 7°C (45°F) and pitch your yeast, following the fermentation instructions as above.