Sour Milk Stout

I've recently brewed a milk stout which I racked onto some cocoa nibs and while prepping to bottle it today (~1 month in secondary) I think it may be infected. I'm planning on just letting it go and see what it tastes like, but I was wondering if anybody had experience tasting a soured (intentionally or otherwise) milk stout.

Did this beer have very low IBUs? Do you normally brew beers that are more bitter?
Second question: AG, PM, or extract?

I believe you can get a sour flavor when you mash some specialty grains like chocolate, roasted barley etc at too high a temp.

Franc103 said:

Did this beer have very low IBUs? Do you normally brew beers that are more bitter?
Second question: AG, PM, or extract?

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All grain and the IBUs were in the mid 30s, calculated. I've brewed the whole spectrum of bitterness and this is my first unintentionally infected brew in 4 years. I'm guessing it came from the cocoa nibs, since they were added in the secondary. I soaked them in a little bit of scotch, but not enough to completely cover them.

BrokenDog said:

I believe you can get a sour flavor when you mash some specialty grains like chocolate, roasted barley etc at too high a temp.

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I haven't actually tasted any sour yet, in fact it tastes like a fantastic chocolate milk stout. The reason I think it's infected is because I can visually see some growth on top of the beer, much like what leads to a pellicle, in my experience. What I was trying to ask with the original post is whether or not I was wasting my time by letting this one play out to see what it tastes like.

I can't remember whether the bugs will eat lactose or not... pretty sure they can, so it'll just be a "sour stout." Not that that's anything other than an issue of semantics, but I have had a sour stout before, and it was great. Jolly Pumpkin's Dark Dawn. I'd let it go and see what happens, personally. Maybe pitch some dregs from something to make sure you get a mix of Brett and bugs?

If it's a "fantastic chocolate milk stout", I'd keg it and drink it while it's 'hot'. Bottling might be a different issue.

If it does sour, you need to call it a "buttermilk stout".

Calder said:

If it's a "fantastic chocolate milk stout", I'd keg it and drink it while it's 'hot'. Bottling might be a different issue.

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That's the problem, I strictly bottle, so I don't want to make any bottle bombs.

othellomcbane said:

I can't remember whether the bugs will eat lactose or not... pretty sure they can, so it'll just be a "sour stout." Not that that's anything other than an issue of semantics, but I have had a sour stout before, and it was great. Jolly Pumpkin's Dark Dawn. I'd let it go and see what happens, personally. Maybe pitch some dregs from something to make sure you get a mix of Brett and bugs?

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There are definitely some bugs that can eat lactose, not sure which ones though. If brett and lacto can eat maltodextrin, then I bet they can eat lactose. I may pitch a mix to make sure I have the whole spectrum, but I'm going to give it a while first to make sure it actually is infected.

ChshreCat said:

If it does sour, you need to call it a "buttermilk stout".

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Yea, I was hoping to go the whole 'sour milk' stout route, but I wasn't sure people would get it. Also, sorry for the multiple responses, I can't figure out how to multiquote on my phone.

mcnewcp said:

There are definitely some bugs that can eat lactose, not sure which ones though.

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If it's infected with Lactobacillus, it will convert the lactose into lactic acid and sour your beer.

A while back I ran into the similar situation with a hoppy Stout I did. For numerous different reasons it sat in secondary for 8 months ignored for various reasons none of which being I wasn't brewing other beer. Anyway, afte not looking at it for a while I saw this.



Is that what yours is looking like? Well, I tasted it and it tasted great, just as it did at transfer from primary. I went back and forth on whether or not to funk it up or just keg/bottle. I took a reading and let it sit for another month, took another reading and it was still 1.012. So I kegged half and bottled half. Fast forward 6 months to today and it is as good as ever, I just keep it all stored cold.

If I were you I would take a reading as I did and come back in a month for another reading. If it hasn't moved you're probably fine, if it's still attenuating well then embrace the funk.

mcnewcp said:

The reason I think it's infected is because I can visually see some growth on top of the beer, much like what leads to a pellicle, in my experience. What I was trying to ask with the original post is whether or not I was wasting my time by letting this one play out to see what it tastes like.

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Some yeast strains and some specific packets of yeast (even those you've used before) can sometimes leave a lingering foam/pellicle-looking slick on top of the beer. I have had this several times and never had an infected batch from one of those times. Nevertheless, it worried me every time.

Take the post above mine to heart, take some gravity readings and if it's stable over a good while, it's probably fine.

But... for the future, don't add agricultural products without sanitizing them somehow if you are worried about infections. And btw, a little scotch isn't necessarily going to kiil off all the baddies.

Coff said:

Is that what yours is looking like?

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Awesome picture man. I tried taking a picture today, but I couldn't get it to come out very well. It's not nearly that advanced. There are 5-10 separate pellicle-looking patches, each about a half inch in diameter. I've already noticed a visible increase since I originally posted this.

Coff said:

If I were you I would take a reading as I did and come back in a month for another reading.

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When I originally noticed this I took a reading at 1.021, which is a bit lower than the FG I normally get from this brew. I plan on taking readings until it stops.

Grizzlybrew said:

And btw, a little scotch isn't necessarily going to kiil off all the baddies.

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You know what they say about hindsight. I've used this method before and never had any problems with infections. I'm just weary of dumping too much liquor in my brew.

i know this is an old thread, but was wondering how this came out. what did you end up doing? i just had the same thing happen to me: stout pitched onto cacao nibs only to find a serious pellicle. here's what mine ended up looking like. cheers!

fivepoundpossum said:

i know this is an old thread, but was wondering how this came out. what did you end up doing? i just had the same thing happen to me: stout pitched onto cacao nibs only to find a serious pellicle. here's what mine ended up looking like. cheers!

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That's a really good pic, but mine didn't form a large pellice, just some little patches on top that slowly ate all the lactose and dried it all the way down. I just took hydrometer readings here and there until I noticed it had stopped. I ended up giving it at least 6 months, mostly just because I forgot about it, and then kegged it. It actually ended up tasting like a pretty decent dark chocolate stout, just completely bone dry. Whatever got a hold of the lactose definitely wasn't lactobacillus because there wasn't even a hint of sour in the finished beer. I may still have a bottle of that in the back of the fridge...