Using Yogurt To Make A Sour

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mrphillips

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A buddy and I brewed up a couple batches today: I brewed a variation on an old APA recipe, and he brewed a Sour Rye Stout. I must admit, I was a little jealous of his recipe, but when I asked him how he was going to turn it into a sour, he said he was going to use yogurt. It had lots of other bacteria in it, but one of them was lactobacilic (or however you spell it). He's keeping it at 90 degrees for a week, then plans to boil it again to kill the bacteria before pitching his yeast. Is this crazy idea of his going to work? God I hop it does.
 
Is this crazy idea of his going to work? God I hop it does.

Yes, and maybe no.

Many of those organisms are lactic acid bacteria, which is what he wants. Unfortunatly most lactic acid bacteria (not all), are adverse to hops; that is, if there are hops present, they will remain dormant. Some can't tolerate any hops, some are ok to about 10 IBUs, anything more, and it is a rare strain that will survive.

The way to do it, is to add the bacteria before doing the boil and adding the hops. If you only want it slightly sour (ala guiness), you can just sour a small amount and add that to the main batch when soured enough.

Also, 90 F is low. I usually go for 100F and have found it takes from 5 to 7 days to decently sour.

I usually do not boil after souring, unless I want to add hops. The alcohol (and low PH) will sort out any bacteria. I usually do this for Berliners which don't have any hops. Some of this bacteria creates alcohol with the lactic acid, and by boiling it, you will be driving off the alcohol, and ending up with a low alcohol beer. To tell what you have, check the gravity after souring. If you have homofermentive bacteria, the gravity will be similar to the starting gravity. If you have heterfermentive bacteria, you will see a significant reduction in gravity.

He may get lucky, but I suspect nothing will happen. It all depends on what bacteria he has in there.
 
Thanks for the notes. He did a 60 min. boil with an ounce of warrior hops (I think the AA were 15), so probably nothing will happen.
 
Could always add lactic acid on the bottling or kegging end to get the sourness he wants if the yogurt doesn't work out.

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Well it took a couple days, but the yogurt is doing some real work on the wart! I came home from work yesterday, and there was a freaking stout volcano in my kitchen! Can't tell which bacteria is going to town on it, but somethings happening...so I'm chalking it up as a victory :)
 
Yep. He transfered it into his carboy when the wart was was 90º, and slopped a couple spoonfulls of all natural plain yogurt right in the carboy. Then he wraped a heating pad around it and went home. Crazy stuff.
 
Oh, and he hasn't pitched yeast yet. This is what it looked like last night.

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Wow!!! I've never had lacto go crazy like that. Any idea what yogurt it was. I would like to see what is in it.

Before he boils it, can you ask him to take a gravity reading with an hydrometer. A refractometer reading will not be any good. It would be interesting to see how much it changes.
 
We took the gravity, as well as PH levels, before we added the yogurt. I'll definitely post the results. Should be another 2-3 days. He used "Taste of Inspirations Greek Yogurt Plain," and only put in half of the container (maybe a 1/4 cup...it was a fairly hap-hazard addition to the primary :))

My buddy's pretty sure that it was infected with a wild yeast strand, but I'm real skeptical that any yeast could be that active at 90-100 degrees. Plus, I've never had a wild yeast infection, and everything was boiled/racked in the exact same place as my last 5 beers.
 
Actually, 90+ degrees is where yeast want to work. That is one of the reasons we hydrate dry yeast around 100 F.

I looked up that yogurt, and it has a variety of lactic acid bacteria. I guess one of them is a super bug. Will be interested to see what happens.
 
Subbing this also - this is just too good of a trainwreck to miss.

Greek Sour, who'd a thought it would take off like that. :D
 
I successfully used yogurt for my one and only Berliner Weiss. I chose that path from necessity while living in China. Actually I guess the opposite is true. I saw the few English words on the package on top of my fridge and it spoke to me requesting to become a beer.

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I intended to only sour the mash, holding it between 100-108F easily in the Shanghai summer heat.

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No harm. Probably improved it my increasing the sourness some. That strepto strain created some black threadlike growths, but they seemed to stick to the walls and yeast cake, so it didn't appear to carry into the bottles. I could never detect any off flavor that would have been attributed to it. Very few threads were present.
 

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Posted that with the mobile app. It certainly didn't come through as entered. On the web version it now shows multiple copies of images. On the mobile, one image is missing.
 
WooHoo! I'm in good company! Haha.

Fermentation is still bubbling along, though slower than 3 days ago. Krausen hasn't dropped yet. I'm hoping mine looks like Quaker's when it's done. That's what it's supposed to look like...isn't it?
 
We bottled this disaster 3 days ago. It tasted quit bitter (from the warrior hops), and the rye malt gave it an odd flavor...but that just might be because I'm not a huge fan of rye. It also had a skunky flavor to it, but I'll also say that it's not the WORSE thing I ever tasted.

We're gunna crack a bottle in another week. We'll see how this saga continues then.
 
In a word...depressing. Haha! Came out tasting like rubber bands and rye. My buddy still has a ton of bottles left, so maybe they won't make us puke in another year. Honestly, I'm not gunna hold my breath.
 
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