Berliner Weisse – the old-time kettle-souring technique

10

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!