Sour Mashing (Declassified)

Infusion, Decoction, Step, etc

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Roachbrau
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Sour Mashing (Declassified)

Postby Roachbrau » Wed Oct 14, 2015 7:49 pm

Here's a riddle... Ideal mash pH is 5.4-5.6, ideal boil pH is 5.2-5.4. Sparging raises pH, and by the Reinheitsgebot, German brewers aren't allowed to add acid to their beers. So how do they get to the ideal boil pH?

The answer is sour malt and/or sour wort. Sour mash can be added before lautering, and sour wort would have to be used for any necessary kettle adjustments. I don't think they're dropping the pH until after sparging is complete, the reason being that the sparge can release additional starch, and alpha-amylase is needed to convert this starch before it makes it into the kettle; the alpha would be inhibited by the low pH if it was lowered before sparging, hence the necessity of adding soured wort to the kettle, in addition to the sour mash used during mashing.

I, like most other homebrewers, use lactic acid to control my brewing pH; lactic acid has it's own distinct flavor, but a fermentation by lactobaccillus in a sour mash is going to produce a whole lot more byproducts and flavors than purified food-grade lactic acid...

I started thinking about other foods that use bacterial fermentation for acid production; sourdough bread, yogurt, and cheese all come to mind. Again, there's a whole lot more going on in these than the one-trick pony of lactic acid.

As far as beers go, Belgian lambics that use a slow cooling process and spontaneous fermentation most likely have a good amount of lactobaccillus fermentation going on in the initial cooling period before they are transferred to the fermentors. Lambics can have a hard-to-describe mineral/citrus/floral character that is not entirely unlike what we refer to as "IT" in continental lagers. Speaking of German beers...

The only German sour beer I have ever tried was Professor Fritz Briem 1809 Berliner Weisse. I only had it once, and it was a while back, but I remember thinking it had a character similar to a Bavarian Weisse, but with the additional sourness and funk added by the other bacteria. It certainly tasted like an authentic German beer, though.

I'm going to experiment with sour mashing and souring wort. I already have a cellar full of fermenting sour beers, so I'm not worried about contaminating any of my equipment with wild yeast and bacteria.

I found a little snippet about how commercial breweries are making there saurgut here: http://discussions.probrewer.com/showthread.php?47820-Lactobacillius-vs-Lactic-Acid If I'm reading this right, they have a continuous sour fermentation going, and then draw wort off from this to use to adjust pH during mashing. I could do this by just keeping a lactobacillus-only fermentation going in a small glass jug; I know some strains of lacto are sensitive to hop bitterness, but hopefully I can get a strain going that is robust enough to sour extra wort I have left over from each brew session, otherwise I'll have to make special un-hopped wort to feed the culture, or feed it with pre-boil wort from each brew.

Anyway, I'm going to attempt it, and see if it adds anything. This method seems like much less of a pain than making a little sour mash several days before each brew session.
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Re: Sour Mashing

Postby admin » Wed Oct 14, 2015 8:08 pm

This is exactly what Bayerischer Bahnhof does, in Leipzig, for making Gose. In their case, they adjust souring pre-boil.

https://www.facebook.com/groups/germanb ... 673110021/
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Re: Sour Mashing

Postby Bryan R » Wed Oct 14, 2015 11:14 pm

REALLY REALLY interested in this. Can't wait to see results.
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Re: Sour Mashing

Postby Roachbrau » Fri Oct 16, 2015 6:20 pm

Ok, I've been thinking about how to pull this off. I think what I'm going to do is mash a 1 gal batch and inoculate it with crushed grain.

I'll mash at 149 for high fermentablity - Michael Tonsmeire says here that lactobacillus prefers simple sugars. http://www.themadfermentationist.com/2011/03/maintaining-brett-and-lacto-cultures.html?m=1 I won't worry about boiling the saurgut wort, as it will be added for pH adjustment pre-boil anyway. Whenever saccharification is complete, I'll siphon the wort into a glass jug filled to the brim and inoculate with crushed malt. Lactobacillus is anaerobic, and most spoilage organsims and molds need oxygen, so I'll use an airlock with minimal headspace. I'll put the "starter" in my mashtun with as much of a water bath as possible, and try to keep it in the ideal temp range of 105-120 for as long as possible, or until it seems like fermentation has stopped. When the lacto is no longer active, I'll move the starter to the fridge to hopefully prevent spoiling.

I'll check the gravity and pH of the starter as often as possible while it's "fermenting." I have a winemaking titration kit, so I should be able to calculate the actual percentage of acid in the saurgut, to make calculating additions on brewday easier.

I'll use the saurgut just like I normally use lactic acid in the mash and preboil; whatever I use for each brew, I can replace the volume in the starter with unhopped preboil wort. Essentially I'll have a continuous lactobaccillus fermentation going in the jug, being used and refreshed each brew day, so it should keep the bacteria going indefinitely; it's pretty similar to how commercial breweries maintain a yeast brink.

I honestly have no idea if this will make any difference at all in the final beer, but in an extremely beer-nerdy way, I'm excited about it. Since I switched to pressurized secondary fermentation, this is the last step for my beer to be 100% Reinheitsgebot compliant!

Wish me luck!
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Re: Sour Mashing

Postby Bryan R » Fri Oct 16, 2015 9:18 pm

DUDE! Yes. So excited for the results.
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Re: Sour Mashing

Postby Roachbrau » Sat Oct 17, 2015 4:57 pm

Made this little experiment today. I did a stovetop heated step mash, no sparge, ended up with 3L of wort @ 11°P. Heated almost to a boil, then transferred to a glass jug with airlock and placed in a water bath in my cooler mash tun @ 115f. I let the wort cool for about a half hour, then pitched about a cup of crushed floor malt. It's been about 2 hours now, and the airlock is definitely letting off pressure, so something is happening.

I'll try to check the pH and gravity every 12 hours or so until it stops changing, then check the acidity via titration, and store it in the fridge.
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Re: Sour Mashing

Postby Roachbrau » Thu Oct 29, 2015 1:25 am

Not much to report on this yet. I held the temperature in the cooler between 40-50c (104-122f) for 4.5 days. The gravity dropped from 11P to 9P on the first day, then didn't change. Over the course of 3.5 days, the pH fell from around 5.4 to 3.0. I figured that was about the limit for what the lacto could do, so I moved the starter to my keggerator.

Before I use it in a brew, I'll attempt to determine the actual acidity percentage of the saurgut by titration, and take a pH reading.
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Re: Sour Mashing

Postby Roachbrau » Thu Nov 12, 2015 7:47 pm

I used the saurgut for the first time last week.

The pH was still right around 3.0, I forget exactly. I used a winemaking titration kit to check the acid, it ended up requiring 4mL of base to neutralize the 3mL sample. According to the kit instructions, this is roughly 1% acidity, expressed as tartaric. I have no idea how to convert that to find the actual lactic acid percentage, but whatever, it's a number to compare against in the future.

I ended up using 1L of saurgut in the mash for a 24L batch of Pils. The initial pH was 5.82, and the saurgut brought it to 5.32 - below my target of 5.4, but meh. An additional 300mL was added 15 minutes into the boil to correct the preboil pH of 5.53 down to 5.29. Final castout pH was 5.26.

We'll see how it turns out. One note: I failed to account for the fact that I was adding a substantial amount of cold liquid to my mash, so I screwed up my first rest temperature. It would make sense to calculate a conservative amount of saurgut and add to the strike water beforehand. Doesn't really affect the boil.

I replaced the volume I removed from the 3L saurgut jug with fresh hot preboil wort. This brought it right back up to the 45-50C lacto fermentation range. I inoculated it with a little fresh dust from the mill, then placed it in the mash tun (with the grain still inside, for thermal mass) for a day, then put it back in the lager freezer. Hopefully it fermented, I haven't checked it, but will the next time I brew.
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Re: Sour Mashing

Postby Weizenberg » Fri Nov 13, 2015 6:26 am

Roachbrau wrote:Here's a riddle... Ideal mash pH is 5.4-5.6, ideal boil pH is 5.2-5.4. Sparging raises pH, and by the Reinheitsgebot, German brewers aren't allowed to add acid to their beers. So how do they get to the ideal boil pH?

The answer is sour malt and/or sour wort. Sour mash can be added before lautering, and sour wort would have to be used for any necessary kettle adjustments.


Indeed! However, sour (or Acid Malt) makes for a much better flavour than Lactose @ 80% -- So the tradition has it's justification. It's a bit trickier when it comes to sparge water. The distinction is made between 'technical' acid and 'biological' acid. Technical being the Lactose, Biological being the acid gained from malt.

For home-brewers this can be quite challenging, thus most use Lactose (lactic acid) to lower the sparge water pH and to adjust the wort pH (15 mins before end of boil -- not for before, unless you want your hop utilization rate dropping through the floor).

The other option is the famous acid rest... but who wants to go through the expense of holding a mash temperature for 8 - 12 hours with the danger of it going off?
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Re: Sour Mashing (Declassified)

Postby Bryan R » Mon Mar 14, 2016 8:18 am

So my intent was always use acid malt for the inoculation, then I ordered these ( http://www.amazon.com/gp/product/B00N2T ... ge_o06_s01). Make a full 20l batch. Then divide up the batch in these containers and freeze. Take out the night before brew day( and or place in the microwave), use what was needed and either then discard, or refreeze. Looked at this method as well... http://sourbeerblog.com/fast-souring-lactobacillus/

However my current process along with just 2% of acidulated malt, gets me everything I want and more, so this never came to fruition.

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