Easy Sour: Sour-Mash Berliner Weiss

Grain Bill: 50% Wheat Malt 50% Pils

This weeks beer is a wonderful summer beer that can go from mash tun to glass in as little as a week. This style is rarely found outside of Berlin, despite having a long-lasting reputation as the “champagne of the north”; an appellation provided by Napoleon’s troops during their conquest of Germany.

Berliner Weiss (or Weisse) is a deceptively simple sour beer. Its key characteristic is a taste-forward sourness, provided by ample quantities of lactic acid. Low in alcohol, effervescent and dry, with a lactic acid pucker, this beer is great for hot days, patios & BBQs. Its intense sourness is not enjoyed by all, so it is commonly served with simple syrup (‘mit schuss’) or flavoured with either woodruff (‘waldmeister’) or raspberry (‘himbeer’) syrups. It is often considered the most refreshing style of beer.

Warming the mash water

Berliner Weiss recipes are simple; all start with a 50/50 mix of Pilsner and Wheat malts, and some add in a bit of table sugar to dry out the beer. Minimal hop flavour/aroma is provided by a light hopping with German hops. Starting gravities are typically 1.028 – 1.032, producing an alcohol content of 2.8-3.5%. From here the style can remain simple, or get quite complex. Lactic acid bacteria like lactobacillus or pediococcus are used to provide a strong dose of lactic acid, while neutral ale yeast ferment out the beer. Some feature a mild Brett character which adds a hint of fruitiness and funk to the beer.

There are two major ways Berliner Weiss can be brewed – a classical sour ferment, or a more modern sour mash. Sour ferments are the same as for Belgians sours: months-to-years in duration, complex, and unpredictable. Sour mashes are the polar opposite – and an excellent entry point for a brewer interested in sour beers. Instead of relying on souring organisms in the ferment, a sour mash instead introduces them into the mash. Over a few days the mash sours, after which the sparge and boil kill these organisms. The beer can then be fermented with a clean ale yeast, kegged, and be ready to drink in as little as 7 days after the mash is started.

As always, the meat is below the fold.

Sour Mashing

A cooled mash, innoculated with
uncrushed Pilsner malt.

Sour mashing is a simple process, and one which allows sour beers to be produced without the long ferments and separate fermenters/siphons/etc that is typical of a sour ferment. To begin a sour mash, dough-in as normal, but using the smallest amount of water possible (I used 2L/kg; roughly 1pt/lb). Instead of sparging, the mash is cooled to ~40C, at which point a small amount of uncrushed malt is mixed into the mash, thus dosing with some wild lactobacillus. The mash is then sealed from oxygen under a layer of CO2 or tin foil, and allowed to sour.

A sour mash, insulated with
sleeping bags and monitored
with a meat thermometer.

The mash temperature needs to be maintained at 30-35C for the ~48 hours it takes to sour the beer; if a heating system (electric smoker, hot tub, etc) is not being used, the mash needs to be checked every 8 or so hours, and if cool, boiling water added to bring the temperature back up (this is why we use a minimal-volume mash).

Sour mashing requires three things to work well – temperature, CO2 and tasting. At these warmer temperatures, harmful and bad-tasting bacteria are inhibited, while the lactobacillus will be growing at an optimal temperature. These characteristics are aided by the absence of oxygen, provided by the CO2 or foil blanket covering the mash. Finally, by tasting the mash (usually starting at 24 hours, and every 4-8 hours after that), the souring process can be stopped when the desired sourness is achieved.

You will not want to taste the mash. The aroma is horrific, and every instinct in your body will rail against tasting the mash liquid. But do not fear – the lacto is not harmful (some strains are even probiotic), and the aroma does’t reflect the taste.

Brewing the Summer Sour:

Mash Day (Thursday, Day 1):
An hour with the lid open
and it still too warm!
“Reverse decoction”
I was aiming for a mash temperature of 67C; I slightly undershot this, and needed a short decoction to warm the mash to the right temperature. An hour later the mash was complete. I opened the mash tun to let it cool, but an hour later the temperature was far too hot (60C), so I “reverse decocted” the mash in a sink of cold water to reduce the temperature to 40C. At this point ~2 cups of uncrushed pilsner malt was mixed in, the tun filled with CO2, the lid closed, and the whole thing insulated using camping sleeping mats and down sleeping bags.
24 hours (Friday):
24 hours later it was time to check the mash. My thermometer reported that the temperature had dropped to 32C, so I added 1.5L of boiling water wo get the temperature back upto 36C. At this point the mash had a horrific aroma – if you’ve ever smelled grain in a compost bin you’d recognize the aroma. I held my nose and took a small sip – a slight sourness was present, but not nearly enough. The system was re-sealed, and left for another day.
36 Hours (Saturday AM):
The temperature was at 34C, but I had coffee to brew, a lawn to mow, and some hop plants to trellis, so I didn’t take a taste.
44 Hours (Saturday Afternoon):
The days work done, it was time to check on the beer. The temp was still at 34C, but the aroma had progressed to something on par with a week old corpse. Fighting back the bile, I managed to force a 1/4 teaspoon of the foul, cloudy liquid into my mouth. Much to my surprise, it was fantastic! Sweet, with a balancing tartness. The tartness was unique – lacking the punch of vinegar (acetic acid), it instead was smooth and mellow, with a silky mouth feel. Get rid of the aroma, and the unfermented wort would be a fantastic beverage on its own.
The Actual Brew:
The first runnings
Hot break
I drained the disguising looking mash into the kettle and then batch sparged with a single addition of 19L of 75C sparge water. The pre-boil gravity was 1.030, meaning it was unnecessary to add the optional sucrose (table sugar) to hit my desired OG of 1.032. Unlike what others have reported (and I experienced with previous batches), I didn’t get a nasty thick layer of hotbreak – instead mine was thin and bubbly. After the break I put in my immersion chiller, brought the beer back to a boil, then added 25g of Hallertauer hops.
Fifteen minutes later the boil was done!  Yes, that is all that is needed – we’re killing the lacto & extracting a little hop flavour. I quickly chilled the beer, transferred it to the fermenter, and pitched a 2L starter of Wyeast 1056 (American Ale). Within 2 hours there was visible signs of fermentation, and by Sunday morning a thick kraussen covered the top of the fermenter.

Check back in a week or two for the tasting notes!

Summer Sour
Berliner Weiss
Type: All GrainDate: 13-05-30
Batch Size (fermenter): 20.00 lBoil Time: 15 min
Boil Size: 22.75 l
1.50 kgPilsner (2 Row) Bel (2.0 SRM)Grain150.0 %
1.50 kgWheat Malt, Bel (2.0 SRM)Grain250.0 %
180gTable Sugar (sucrose), optional
25.00 gHallertauer [4.80 %] – Boil 15.0 minHop38.8 IBUs
1.0 pkgWyeast Labs #1056, from bankYeast4
Beer Profile
Est Original Gravity: 1.030 SGMeasured Original Gravity: 1.032 SG
Est Final Gravity: 1.008 SGBitterness: 8.8 IBUs
Estimated Alcohol by Vol: 2.9 %Actual Alcohol by Vol: 2.9 %
Est Color: 2.7 SRM
Mash Profile
Mash Name: Single Infusion, Light Body, No Mash OutTotal Grain Weight: 3.00 kg
Sparge Water: 19.46 lGrain Temperature: 19.0 C
Sparge Temperature: 75.6 CTun Temperature: 18.0 C
Mash PH: 5.20

Mash Steps

NameDescriptionStep TempStep Time
Mash InAdd 6.55 l of water at 78.1 C68.0 C60 min
Sparge Step: Batch sparge with 2 steps (Drain mash tun, , 19.46l) of 75.6 C water

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