At the end of April 2017 we were able at last to brew a beer style we had wanted to brew for a long time, Kölsch. We hadn’t brew it yet because we hadn’t been able to get the right yeast for this style. This German style, specifically from Cologne, depends to a great extent on the yeast used to ferment the wort.
When we say that this style in specifically from the city of Cologne is somewhat literal, since outside of the city borders you cannot sell beer with described as Kölsch, as it was stated in the Kölsch Konvention in 1986 by 12 brewers from this city in the West of Germany crossed by the Rhin river.
Talking about the characteristics that define this style, Kölsch are clear top fermented ale beers, the wort has to be 11º-16º Plato (or 1,044-1,065 specific gravity) by law, they are highly attenuated and hop accentuated and have a long lasting white foam. The majority of the production is consumed in the city of Cologne, usually from draft, served in small, 200 mL cylindrical glasses known as stangen. In November 2017 we were able to spend some days in Cologne touring the city and we could live this first hand visiting the city breweries. We also traveled to the nearby Düsseldorf to taste its Altbiers, but we will talk about all this in a future post, let’s talk now about brewing Kölsch.
By a quirk of fate, as we were planning our recipe, the 2017 may/june Zymurgy issue arrived and it had an article about Kölsch and Cologne breweries, which served us as a base for the recipe design and for our future trip to Cologne. Following the guidelines from that article, and with a little more information from different books and websites, we learn some things about the style that would help us to define our recipe.
As we previously mentioned, probably the most important thing when brewing Kölsch is yeast. They are very specific ale strains that ferment at a relatively low temperature for ales (15ºC-17ºC or 59ºF-61ºF) and produce clean, dry beers with an ester touch. This is how they describe the yeast we used in the Giga Yeast website, Kölsch Bier Yeast GY021. It is supposed to be sourced from one of the oldest breweries in Cologne. It is a liquid yeast, packed in the characteristic Gold Pitch from this brand and, as their instructions address, it doesn’t need a starter when pitching in 19-20 liters of wort (about 5 gallons).
Apart from the yeast, the rest of the ingredients are not complicated. In the case of grains, a Pilsen malt makes usually the majority of the grain bill, with the possibility of using other additional malts in low percentages to increase body and/or foam (cara-pils, wheat malt) or to add complexity (Vienna malt, Munich malt). Hops, evidently, must be from Germany, usually noble hops, and they are used mostly for bitterness. Last, water from Cologne is slightly mineral.
Having all of these into account and, from what we have in stock, we design the following recipe:
1.00 Kg (2.20 lbs) (45.7%) Pilsner Premium (Weyermann) (2.0 EBC)
0.84 Kg (1.85 lbs) (38.4%) Bohemian Pilsner – Floor malted (Weyermann) (4 EBC)
0.25 Kg (0.55 lbs) (11.4%) Vienna malt (Weyermann) (7 EBC)
0.10 Kg (0.22 lbs) (4.6%) Cara-Pils (Weyermann) (5 EBC)
15.00 g (0.53 oz) Spalt Select (4.60% AA) leaf (boil 60 minutes, 18.5 IBUs)
7.00 g (0.25 oz) Spalt Select (4.60% AA) leaf (boil 30 minutes, 6.6 IBUs)
Kölsch Bier Yeast from Giga Yeast (1 Gold Pitch sachet, directly inoculated)
Volume: 9.5 L (2.5 gallons) OG: 1.046 FG: 1.006 ABV: 5.2% IBUs: 25.1 Color: 6.5 EBC BU/GU: 0.546 Efficiency: 65.00%
Ca: 38.5 ppm; Mg: 3.4 ppm; Na: 7.4 ppm; SO4: 12.4 ppm; Cl: 12.6 ppm
65ºC (149ºF) for 75 minutes, mash out 75.6ºC (168ºF) 5 minutes
As you can see in the recipe above, there are two different Pilsner malts. That’s only because we didn’t have enough of either of them to brew the entire batch, so we combined both. These two malts made a little more than 84% of the grain bill, with some Vienna malt to give some color and complexity and a little percentage of Cara-Pils to enhance body and foam. For this beer we didn’t modify our water since the one in our area is low in mineral content and allegedly suitable for the style. We set mash temperature at 65ºC (149ºF) to try to obtain a quite fermentable wort.
In the morning of the brewday we boiled water for 20-30 minutes to eliminate chlorine, having into account that, after evaporation, we were going to need almost 18 liters (4.8 gallons). At the start of the mash, after adding grain, the temperature was as planned (65.4ºC or 149.7ºF). For a while we kept some heat in the induction hob to keep the mash temperature. After half an hour, we increased the heat since the temperature have dropped a little bit and we left it that way… until we were entertained with other things and when we came back the mash was out of control. The temperature had been raising and now the mash was at 80ºC (176ºF). ¡You have to be careful with these idle times! After the shock, we removed the grain and take a reading of the preboil gravity. It is a few points above the theoretical value (1.037 vs 1.030), so we take a deep breath. The fact that the mash was more than 30 minutes at the right temperature and that we also milled the grain more than usual (we used our old Corona mill instead our roller mill because we forgot to charge the batteries of our drill) seemed to be enough to convert starches into fermentable sugars.
During the boil, we added German noble hops at 60 and 30 minutes to the end of the boil and, when finished, we removed hops and we tried to cool the wort as soon as possible with our immersion chiller. We cooled it until it reached 23ºC (73.4ºF) and then we transferred it to a plastic bucket, previously sanitized, to try to low the temperature a little bit more, since our idea was to ferment at about 16ºC (60.8ºF) during the few first days. We cooled the wort until 17ºC (62.6ºF) and then we splashed it between the plastic bucket and the kettle to get some oxygen. Finally we transferred it to a PET demijohn that was going to be our fermenter for this beer. Original gravity was just as the theoretical value, 1.046. Probably, since we ended with a little more volume than expected, the few points we were off before boiling had been corrected now.
Fermentation didn’t show visual signs for the first 48 hours after pitching, so we increase our fridge temperature until 16ºC (60.8ºF). A few hours later, a krausen started to form and the airlock started bubbling, faster as the time advanced. On the fourth day, the krausen reached its highest point and, from the fifth day onwards, both activity in the airlock and the krausen started to disappear. From the sixth day until the eighth day we increased progressively the temperature until the beer reached 20ºC (68ºF), with the intention of giving the yeast the opportunity of eliminating diacetyl and other undesired compounds.
After a couple of days at 20ºC (68ºF), we set the fridge at 6ºC (42.8ºF) to clear the beer before bottling the next day. We measured the final gravity, 1.010, four points above the theoretical value, 1.006. An apparent attenuation of 77.5%, while the specifications for this yeast describe an apparent attenuation of 79-83%. The causes for this little difference can be several, but we think it could have been due the problems during the mash or to a insufficient number of yeast cells pitched. This number should be enough pitching directly without a starter, but you never know the viability of the yeast without testing it. The thing is nothing serious. Color and appearance of the beer are exactly as we planned, and it has only a little less alcohol, it finished at 4.7% ABV. We added enough sugar, previously dissolved, boiled and cooled down, to get 2.5 volumes of CO2 and we bottled approximately 9 liters (2.38 gallons) of beer, 27 bottles of 33 cL. We kept these bottles at room temperature, 19ºC-20ºC (66.2ºF-68ºF) for 17 days and then we put them in the refrigerator for lagering before consuming them. In a future post we will tell you how it all ended.