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11/04/10 01:12 PM  
Sour Mashing in a Controllable Manner
Sour mashing is a very easy way to get a controlled amount of sourness into a beer. You wait for the sour level you want, and then brew, halting the souring and giving you complete control over the consistency of teh sourness.

The problem has always been controlling the aerobic bacteria in the mash and preventing it from getting too smelly. Enteric bacteria, among other sorts, produces a lot of really poopy/vomity/nasty flavors/aromas in some sour mashed beers. Trying berliners and goses at GABF, you could tell which ones were sour mashed for this reason.

A good homebrew solution I recently came up with is to sour mash in a corny keg. Purge with CO2 prior to mash in, rack in hot liquor quietly, pour in grain, stir, purge the headspace again with CO2 and then keep under CO2 pressure for the duration of the sour mash.

I recently used this method and sour mashed for 96 hours. During the entire duration of the sour mashing, there was no foul odor coming off the mash at all (when I opened the corny to take pH readings). After the 96 hours, I just dumped the mash into my normal lauter tun and proceeded normally. There was no foul smells during the sparging, and no foul smells during the boil.

At no point did I pick up any sort of rotting aroma, or poop aroma, or any other signature aroma that you normally get with sour mashes.

Granted, the beer I made was a porter, so there could be some slight notes of poo that are covered up by the roast. I plan on making a berliner weisse with this method soon which should be a better metric on just how clean a beer this method can make.

But with the results I got with my first try, I think that this is the "correct" way to sour mash. No other method that I can think of will give you nearly as much of a barrier from oxygen as this one.

Josh O.
11/04/10 01:58 PM  
Re: Sour Mashing in a Controllable Manner
Chris, thanks for this post. I've been researching sour mashes and working up the gumption to try my first-- the main hang-up has been a fear of a vomity mess at the end of a lot of effort, and whether the smell would ever leave the cooler that I use for a mash tun afterwards... I was going to try the sour-worting method, but this seems like it could be better.

Did you do the saccharification mash in the cooler as well, and let it cool down to sour mash temps (90 - 110 are ideal, as I understand) or did you raise the temperatures back up after the sour mash and do your starch conversion then?


11/04/10 02:08 PM  
Re: Sour Mashing in a Controllable Manner
Thanks for posting this! I'll be trying this method shortly on a berliner.
11/04/10 02:18 PM  
Re: Sour Mashing in a Controllable Manner
Mash in in the keg at sacc temps, let it cool down over night, add some more grain and let it sour from there. Keep it as warm as you can (I could only keep it at room temp because my ferm fridge/incubator was in use).

This would work just as well for sour worting. The only problem with that is it is not quite as ideal in the oxygen control department. You will inevitably pick up oxygen during mash in and lautering. Whether or not the amount of oxygen you pick up during those steps prior to getting the wort into the corny keg is significant, I don't know.

I don't know how necessary sour worting is though. In my experience, the pH of the mash will be nearly identical to the pH of the post boil beer. There is very little pH change of the runnings throughout lautering/sparging.

11/04/10 07:27 PM  
Re: Sour Mashing in a Controllable Manner
Very cool Chris. I love when good homebrewing ideas lead to new and innovative ways of doing things. I may just have to try this out after my aging of pure lacto BW's are finished for comparison.
11/05/10 08:15 AM  
Re: Sour Mashing in a Controllable Manner
Sounds like a promising idea that I might try out sometime.

But doesn't pouring all the grain in introduce oxygen? You're purging keg with CO2, then purging head space, but isn't there a whole bunch of oxygen stuck to all the grain particles? Maybe the point is that there is relatively so much less O2 than a standard mash.

Seems like this gets the advantages of sour worting in a controlled atmosphere (CO2 purged carboy) without the extra steps and work of sour worting.

01/20/11 01:39 PM  
Re: Sour Mashing in a Controllable Manner
Tried this method about a week ago on a Berliner with a 50/50 pils and wheat mash. Racked the water into the keg, then added the grains on top, mixed gently, purged, and set on a heating pad for about 4 days (producing a lovely poop/vomit perfume). I am getting ready for try number two, but this time I am going to rack the water onto the grains in the keg, mash hop with about and ounce of noble hop, and purge through the outlet to try and drive as much 02 out of solution as possible. After a few hours, ill add a handful of crushed grain, and purge again. From there I will check the progress daily to monitor for acidity and off-flavors. I'll post back in a few to let everyone know how this goes...
01/20/11 01:40 PM  
Re: Sour Mashing in a Controllable Manner
Also, FWIW, I know that the Bell's Oarsman is produced via sour mashing, and it is clean and substantially tart, so positive results are possible.
01/23/11 04:07 PM  
Re: Sour Mashing in a Controllable Manner
I just tried this last week but instead of mashing in keg, I mashed in my normal tun, performed a mashout, and then moved the wort into the keg. From there, I threw in some crushed grain and kept it heated with a fermwrap. The sourness was very clean and after 4 days at 120F, it was quite sour.

I was a bit worried about oxygen, so I actually hooked up the co2 to the liquid out post and let it bubble up from the bottom. I'm thinking that this may have helped in clearing the head space of O2, but who knows. The batch is currently fermenting but from tasting the wort, I'm pretty sure it's a winner.

01/24/11 02:12 AM  
Re: Sour Mashing in a Controllable Manner
Things are looking good on this end as well. After 4 days, the wort in the keg was quite tart and clean, so tonight I dumped the contents into my mash tun, batch sparged and then simmered the collected wort for 15 mins. The wort was then cooled to 68 and pitched with a 800mL starter of German Ale. More results after the ferment, but as DaveG said, taste is spot on currently.

And just out of curiosity, would the acid produced in this sour mashing/worting distort the initial gravity reading since sugars are being consumed?

01/25/11 03:52 PM  
Re: Sour Mashing in a Controllable Manner
It's been awhile since my only sour mash experience. I thought temperature (keeping above 110*f or so) was as important as the oxygen barrier to keep the enteric bacteria and other nasties at bay.
01/30/11 03:04 PM  
Re: Sour Mashing in a Controllable Manner
This thread inspired me to try making my own lactobacillus culture. 2 days ago I cooked up about a quart of 1030 wort and once it cooled to about 120 I added it and 8 ounces of crushed malt to a pre-heated thermos. Capped it and left it to sit undisturbed. Start temperature was 115.

Today I checked it out. The smell was not sour. Vaguely rotten mash smell. Not too bad though. The taste was VERY sour (plus an after taste of cooked canned corn). Temperature was down to 94 degrees and pH strip tested to be under 3.8.

Neato! I'm planning to brew a golden brett beer this week. I think I'll just add this to the mash after I drain the first runnings. This should help filter the grain and keep the sparge pH in check. If it works out maybe I'll go for the unpasteurized version and add a starter like this to the cooled wort.

02/11/11 02:23 PM  
Re: Sour Mashing in a Controllable Manner
So here we are weeks later and the beer is young but carbonated. I've had a chance to sample it quite a bit and it has a great taste but there's a slight off smell. Honestly, it kind of smells a bit like urine :X

I'm thinking that I might have got a bit too much oxygen into solution when going between the mash tun and boil kettle to mash out.

I'm thinking of a new approach for a second test batch. I have no clue if enterobacter is responsible for the piss-like aroma, but I've read that enterobacter generally dies off at around 4.5 on the PH scale. I'm considering adding a fairly decent percentage of acid malt to the grist so that my pre-sour mash PH is around 4.5. From there, I'll let the lacto do it's work and take it down into the low 3s where I like it.

Any suggestions on the viability of this method?

03/23/11 11:55 PM  
Re: Sour Mashing in a Controllable Manner
I have sour mashed a portion of two batches using a half gallon growler filled up to about an inch of headspace and then covered with foil. I keep it warm for 2-3 days (between 90-120). I have never had anything truly horrific in the smell but it does smell a bit like cream corn left out too long. No vomit/shit smells.

The smell continues into the boil and even a little after. I find that the boil drives off a lot of the smell and fermentation drives off the rest. The end result is a noticeable tartness and no corn or rotting smells.

I do mash the liquid and then remove it from the grains and only sour mash the liquid with a few fresh grains. I don't know if the absence of a lot of grain material would help prevent the nasty stuff some of you are getting in your sour mashes or not.

03/24/11 05:33 PM  
Re: Sour Mashing in a Controllable Manner
<<I do mash the liquid and then remove it from the grains and only sour mash the liquid with a few fresh grains. I don't know if the absence of a lot of grain material would help prevent the nasty stuff some of you are getting in your sour mashes or not.>>

No, it doesn't matter. I've only every soured the liquid and it can still turn vile. I think the key is oxygen exposure, or lack there of

04/12/11 10:19 AM  
Re: Sour Mashing in a Controllable Manner
I've only ever done a couple partial sour mashs.

In order to control the enteric flavor I used some of the sourdough starter I maintain. I was very happy with the mild tartness that I got and there were no unappetizing smells.

After all sourdough is simply a mixed culture of acid tolerant facilitative anaerobes that like to eat starch, mostly from the flour and local air, that are mildly selected for production of non-nasty sour flavor.

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