Brewing a Historic Berliner Weisse

It’s March, and I’ve been wanting to brew a Berliner Weisse for quite a while. So what better time to brew a Märzen-Weisse?

Relatively little is actually known about Märzen-Weisse. What is known is that it’s a stronger version of a regular Weisse. In his 1947 brewing notes, the brewmaster of Groterjan brewery mentioned a high-gravity version of 16-18 °P that some breweries produced occasionally. I don’t know whether that’s the Märzen-Weisse strength, but it definitely sounds intriguing.

For this brew, I teamed up with Franz Pozelt of Slowfood Berlin, to do one Weisse according to my recipe, and then one Weisse according to his recipe. Last Sunday was the first of two brewing dates.

We started off with a historic Berliner Weisse recipe that calls for 20 parts pale barley malt, 10 parts wheat malt, and 2 parts oat malt. We didn’t know where we’d end up in terms of gravity (because it’s a no-boil recipe, see below), so we used 4 kg Pilsner malt, 2 kg pale wheat malt, and 400 g oat malt.

The mash schedule was also based on historic methods: with dough-in at about 40 °C, we then slowly rose the temperature until we reached 50 °C to rest for 15 minutes. Then we continued to slowly heat up until we reached 62 °C, which we held for 45 minutes. We then drew a thin decoction and boiled it for about 5 minutes. At this point, we also added the hops, literally 3 leaves of Hersbrucker, to boil it. Mash hopping is another historic method in Berliner Weisse.

We then mixed the decoction back to raise the temperature to 72 °C, held that temperature for another 15 minutes, and then moved the mash to the lauter tun. With enough vorlauf to achieve a bright and clear wort, we then went on to sparge. Since this was going to be a no-boil Berliner Weisse, we didn’t know what efficiency to expect, so we simply collected enough wort until we reached 16 °P.

The wort was then heated up to 95 °C, and the temperature held for 20 minutes. This was a bit of a compromise, as older recipes lauter directly to the cooling tub resp. the fermentation vessel, but the Groterjan brewmaster mentions this as a possibility to prevent beer infections (such as Pediococcus) without having to resort to a boil. Interestingly, the resulting wort had 17 °P. That may be due to a measurement error earlier, and we didn’t mix the wort properly before (my experience is that during lautering, the runnings don’t mix well, most likely due to different specific gravity, so you get wildly different measurements with the refractometer depending where you take your sample).

Right after that, the wort was transferred to the fermentation vessel, and cooled down to 30 °C.

Fermentation itself is where my approach deviates from history: to better control the resulting sourness, I decided to sour the wort with a big starter of Wyeast 5335 Lactobacillus buchneri, and when sourness will have approached a good level, yeast will be pitched. I decided for US-05, as it’s a relatively neutral ale yeast which has been shown to successfully ferment even in wort with a pH level of 3.38, plus it’s cheaper for me to get several sachets of it than e.g. a single vial of WLP029 or a smack-pack of Wyeast 1007.

Since the brewday went without any issues, the lacto is doing its work now, and I’ll keep measuring the pH levels and tasting the souring wort. The yeast will be pitched when the sourness is right. In addition to that, the fermentation vessel was used to ferment and mature a batch of porter with Brettanomyces, so I expect an infection with B. claussenii, as well, which is perfectly fine for the style.

I’ll report about any results. At the moment, the lactobacillus is slowly fermenting away, producing some CO2. I suppose that’s fine, as L. buchneri is heterofermentative.

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