Berliner Weisse – the old-time kettle-souring technique


September 18, 2012 by Gail Ann Williams

This summer sure whisked by!  (It’s high time time to write up my notes from the remarkable Berliner Weisse talk at the Craft Brewer’s Conference 2012 in San Diego.  I am going to make this pretty simple or I may not get it written up at all.)

Burghard Hagen Meyer, who teaches brewing courses at the Research and Teaching Institute for Brewing in Berlin, began a presentation on authentic Berliner Weisse (BW) techniques with the astonishing assertion that there is more good BW here (in the USA) than in Berlin.  Then he asked the room of brewers if they had ever brewed one (yes, most hands went up.)  He followed up with the question of whether anybody had a big white persistent head on their version of the beer.  One hand stayed up.  The rest of the talk explained why all those other hands went down, among other things.

Meyer has been researching old manuscripts, brewing and tasting with retired Berlin brewing professors who remember pre-tourism-defined local BW.

Berliner Weisse is a medium body pale acidic wheat beer that has very high carbonation, low alcohol (often traditionally under 3% abv), and about 85% attenuation.  It is made with pale barley malt and wheat malt, including chit malt (the old word for under-modified malt.)

Historically, there were not just low plato “Schankbier“ versions, but also medium and even  “Starkbier“ 16° Plato  and stronger versions, (resulting in a beer of from 7% ABV or higher).

The historical Berliner Weisses resulted from mixed fermentations, and the final product may or may not have had living Lactobacillus left if it, but it did indeed have live Brettanomyces.  ( I notice that my hand written notes have several exclamation marks after that statement.) The mixed fermentation gave some of these beers up to a 70 year shelf life, he reported.

Lactobacillus comes in many species, some of which are heterofermentative and some of which are homofermentative.  (The Lactobacillus Delbrekii that you can buy from the beer yeast companies is homofermentative, and Meyer feels this is less good than heterofermentative species like Lactobacillus Brevis, which is common on malted barley from the malting process itself.)  The heterofermentative  species of lacto put out a more complex mix of CO2, traces of acetic acids, volatile organic acids, alcohol, etc, along with less lactic acid.  (They are less efficient in lactic acid production because they are creating the other compounds at the same time, so this was evidently a sensory/qualitative recommendation.)

Lots of great tidbits in the lecture, like:  DMS was never a problem historically, because of very slow coolship cooling.  (I don’t remember the mechanism, but that’s comforting, anyway.  I also wonder whether it was not that it was never produced, but that the organisms worked with the sulphur compound and made something else out it. Possible?  A new minor mystery?)

Berliner Weisse came to Berlin with the French settlement after the 30 Years War (1618 to 1648) and the Plague decimated Berlin.  (The beer traditions of the French speaking lands that are now part of Belgium immediately come to mind, though there must have been mixed-culture sour wheat beers beyond Wallonia.) The oldest mention of BW in literature is from after that time of emigration, in 1680.  Some of those older descriptions cite 75% wheat malt recipes!

(I was thinking that with modern well-converted wheat malt, not needing enzymes from the barely malt,  a 100% wheat version could certainly be tried and might  be interesting, being mindful of sparging issues and higher protein quantities.)

Decoction mashing was used, with very limited quantities of hops added into the boiled mash portions (so there would be some hop compound isomerization) instead of adding those hops later in the kettle.  Use of a protein rest —  and then often the use of whole hops as a filter bed — both helped prevent a stuck sparge.  (The IBU should end up at ten or less.)   He suggested a 66 C  and a 74 C rest, then up to 85 C to kill everything off.

An acidified mash also helps prevent destruction of foam on the finished beer. The proteolytic activity of Lactobacillus is powerful.   In other words, live lacto breaks down proteins into amino acids. That ruins the beer foam. Lower pH in the mash can reduce that effect.

Up to 50 degree C (122 degrees F) at the maximum, kettle fermentation allows the best environment for the Lactobacillus to grow and perform the acidification.  The lacto will break down some of the large quantity of available protein, then can be killed in the further heating or short boiling, leaving enough protein for a good head of foam.

Heating to 85 degres C, (185 degrees F), to kill the bacteria, rather than boiling, creates a better traditional flavor.  If desired, boil for just 10 minutes. This still gives better color and aroma than a long boil, and is enough for clean wort for fermentation. (These are ample Pasteurization times, in other words)

Meyer suggested brewers play with the grist, even using all under-modified chit malt, including wheat chit malt.

(Wonder what the commercial source would be for those?  Anybody know off hand? Dextrin malt is considered to be close to a chit malt on the barley side of things.)

Meyer’s mixed fermentation sometimes showed ropey viscosity, and he noted that heating briefly helps degrade the exopolysaccharides.  Having been ropey, then thinned by heating was not detrimental to the beer.  “It tasted fantastic,” he said.

(This reminded me of descriptions of Lambic beers that are “sick” and ropey, then thin when summer comes. Mixed fermentation brewers who use commercial Lambic blends see that from the Pediococus. I would love to confirm whether temperature change is involved in that more passive approach to going through and beyond exopolysaccharides (EPS) slime in those beers, too.  It does appear that other Lactic Acid Bacteria species including some Lactobacillus species can create EPS, like their fellow lactic acid producing Pediococus cousins, from some quick reading.  See exampes on Page 5 chart.)

Meyer suggested kettle acidification of the unboiled wort for 6 to 9 hours with L. brevis from malted grain.  The pH was “great” at around 8 hours, he said, after a night of straight linear drop in pH.  (He said that he prefers a mild acidity as being more authentic, compared to some tart commercial examples.)

If you use decoction mashing, the boiling involved will darken the wort some.  Wheat can be handled in a separate mash vessel, then blended to reach 40 degrees C or the desired mash temp.  (This method is well known as cereal mashing.)  Use chit malt (undermodified malt) and do a maltase rest.

Kettle Souring is his preferred technique for authentic BW — also called the “Franken Method.” You drop the temperature after lautering, then pitch your Lactobacillus overnight (6-8 hours to taste).  There is your acidification.  Boil briefly, cool, pitch Saccharomyces, then after fermentation stops, pitch Brett.  Target pH is 3.5 in the kettle.  Target in the mash is 4.8 to preserve the proteins needed for good foam.  (He noted that this technique can use pure lactic acid in the mash, though that would never be used in acidification of the wort itself.)  Over night you will see a fall from 50 C to 38 degrees C in an uninsulated kettle, he said.  (Depends on the size & consturction of the vessel, I’m thinking.)

There is more glucose in wheat than in barley.  Yeast responds to the additional glucose with more esters.  The choice of Saccaromyces yeast strain will have an influence on the fruity esters, and can make the BW distinctive.   L. brevis was the best species of lacto for making BW, and L. casei (found in yogurt and cheeses) had a milder result.  Lacto uses less sugar than yeasts do, and leaves them plenty to work with.

Brettanomyces — alcohol-tolerent and a producer of ethyl lactate & ethyl acetate flavors — was an important art of historic BW.  The Brett needs at least 3 months.  The VOB has banked over 30 German Brett strains.  (Wow!)

Aged Berliner Weisse was a tradition in days of yore.

There was elaborate BW culture and 40 types of special syrups way back in the day.

Consistency is difficult with these beers, he noted.

So there we are, with some new hints on older beers.  In a nutshell, try to kettle-sour instead of doing a mash sour or pitching lacto into the fermentor. You can acidify the mash a bit, mainly  for mash efficiency, not for flavor. Kill off the lactic bacteria after kettle-souring, then consider following up with Brett after primary fermentation by Saccharomyces.

One fascinating note from the Q and A was that Meyer seemed unfamiliar with the American technique of doing all the souring in the mash.  He was responding to the questions as if one would only sour the mash to make the mash work better, not to achieve the needed flavors, which he would get in the kettle instead.

Lots to think about, and try out.  Anybody done this?

(I recently tried kettle-souring a brown rice syrup based beer instead of a wheat beer.  It was pretty good, in a simple, pleasant way.    I did not introduce Brett, and in the next batch I will.  I’ll say more about that, when I get that recipe where I want it. With the brown rice syrup I got from the organic food store I got a touch of nuttiness that I liked a lot, along with a nice apple-like ester most likely from the yeast, lending a sour fruitiness to the finished beer.  (Steve Altimari of Highwater Brewing did a nice commercial “Berliner Reisse” this year, too, by the way, souring a tank of finished beer with a high rice content.)

To the Champagne of the North!


10 thoughts on “Berliner Weisse – the old-time kettle-souring technique

  1. mynerdlyendeavours says:

    Great stuff – thanks for the writeup

  2. Mike says:

    So when you mash out at 85C it kills all the bacteria in the mash, and so you pitch lacto in the kettle. Whereas if you don’t mash out so high, the lacto naturally occurring on the malted barley will live and you do not need to pitch additional lacto in the kettle?
    Im going to try 3 or 4 techniques. Great article.

    • Nice! The advantages to kettle souring would include: 1. Preventing other strains of lacto and other bacteria from contributing flavors in the mash. (That presumes you have a lacto strain you like!) 2. In situations where it is more difficult to clean up stinky mash, this confines the bacterial growth and the mess afterwards to an easily cleaned vessel. That matters more if you are digging out a commercial tun and not so much if you can dump and hose out a homebrewer’s typical picnic cooler tun. 3. I have heard some say that the efficiency of the mash can be compromised by very low levels of pH, so souring in the kettle allows you to have optimum mash pH.

      On the other hand, if you are looking for organisms, you might enjoy the mystery of going with the mixture that is on the grain. One compromise I’ve heard about is using crushed grain to make your starter, growing it up several generations at about body temperature, and thereby favoring the lacto. It would not be a pure culture, but it should be majority lactobacillus. Once you had a sufficient pitch, if you like the aroma, you could go ahead and kettle-sour.

  3. Dean Rouleau says:

    Great recap! I was there and as usual didn’t record all my notes. Your recall is as I remembered. Thanks for your exceptional retelling of his presentation.
    Cheers Dean
    Prodigy Brewing Co SD CA

  4. richard says:

    Hi that’s a great write up, can i ask how much grain you would need to pitch in the kettle for a 10 gallon batch? I’ve been reading lot’s of advice about Berliner Weisse and this method is what i’m going to go for.

    Many thanks

  5. Ehren says:

    Do you really see such drastic acidfication in 8 hours? Also, do you find that heating the mash up to 85 C produces off flavors? And finally, with no boil, to short boil procedures, dont you find problems with DMS?

  6. Not sure any commercial brewery in Berlin ever used the kettle souring technique. The authentic way to brew Berliner Weisse is with a mixed yeast an lactobacillus culture. Souring takes place during primary fermentation, but continues during bottle conditioning.

    • Hi Ron! I made these notes from a lecture, in English, from Berlin brewing professor Burghard Hagen Meyer, to a room full of brewers in the US.

      He seemed to be working on an optimal contemporary method that resonated with history, I seem to recall.

      So the lecture was not about a purely historical recreation of process. I had thought he cited the “Franken Method,” as I noted above. I don’t know who or what Franken may be – but you seem to have solved that mystery with “Franke.”

      I know from your writings that you read German, I don’t, alas. I wonder — can you share insight into what/who that may be?

      • Ron Pattinson says:

        The Francke method dates back to 1906. Unboiled, unhopped wort is taken from the lauter tun, cooled to 45-47º C and inocculated with Lactobaciluis delbruckii. It sours the wort in just 7-8 hours. The sour wort is heated to 80º C to kill the lactobacillus and it’s added back to the rest of the wort, which is fermented with normal yeast.

        The method was soon dropped because beer produced this way tasted different from that brewed the classic way with a mixed culture. In particular, it lacked the aroma produced by Brettanomyces. Methner, who discovered the role of Brettanomyces in the 1980’s, proposed a modification of the Francke method. He suggested secondary conditioing with Brettanomyces to get the right flavour profile. I don’t know if anyone ever tried this commercially.

  7. […] Notes for future reference: 1. Reduce wort pH to 4.5-4.8 with food grade lactic acid before pitching Lactobacillus. This will help with head retention as it reduces proteolytic activity of lactobacillus. Source: Milk The Funk Wiki/Lactobacillus. 2. Target in the mash is 4.8 to preserve the proteins needed for good foam. From article. […]

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