Stuck Fermentation Help (Milk Stout)

[teeWRX]

Hey all.

All our brew days have been going so smoothly lately we decided to try something interesting, and thus have new problems. A Milk & Cookies stout, mashed with 1kg of Oreo cookies and ~450g of lactose added to the boil (recipe called for 400 but the pkg I bought was 450 so... just tossed it all in)

While all our other brews have finished slightly lower than predicted FG, this one was stuck at 1.032.

I already tried to rouse the yeast & toss in another package of Us-05, so I can only assume this one is totally done. But where did I go wrong?

The recipe was sent to us from a local brewery, it's their beer scaled down to ~5gal.

We do BIAB full volume mash, and it was done at 158F. Temp only dropped ~1degree over the 60min thanks to a couple layers of reflectix and a sleeping bag.

Targetted an adjusted version of beersmiths "stout" profile for water. I dialed the Chloride down to 240.

Pitched Us-05 dry (1pk originally), and the beer was room mates in the chamber with our Moktoberfest that fermented just fine (chamber set at 17C/63F). Our original gravity was quite a bit higher than the beersmith predicted (1.058) because I couldn't figure out how to add the 1kg of cookies to the recipe. Didn't get pure 02 for oxygenation, just a quick shake of the fermentor, same as the Oktoberfest.

After the second pack of yeast and rousing it bubbled for about 1day then quit (I had bumped up the temp to 20C/68F prior to pitching the second pack in case temp was an issue). My gravity now is ~1.028. No more bubbling is seen, there is a raft of junk floating on top of the beer that sorta looks like yeast, but I can only assume is from the Cookie? As I have a thick layer of yeast all flocc'd out at the bottom.

I'll attach pictures of the gunk currently on top. As well as my beersmith recipe and water profile to hopefully paint a better picture.

Where did we go wrong?
- Mashed too high?
- Needed pure 02?
- Or does this recipe simply contain so many adjuncts that it was doomed to end up under attenuated?
- Can I save this mess?
- Is it safe to bottle?

Any input would be helpful, cheers.

 

[RPh_Guy]

Hmmmmmm...
High mash temp.
Low diastatic power (LOTS of adjunct starch and specialty malts).
Poor yeast health (dry pitch, low aeration).
Plenty of unfermentable sugar.

What was the mash pH?

If the FG is stable, it's done. Time to bottle and enjoy!

 

[teeWRX]

Hmmmmmm...
High mash temp.
Low diastatic power (LOTS of adjunct starch and specialty malts).
Poor yeast health (dry pitch, low aeration).
Plenty of unfermentable sugar.

What was the mash pH?

If the FG is stable, it's done. Time to bottle and enjoy!

Mash pH was 5.5
Well that is to say we targeted 5.5 in beersmith using my local water profile. I don't own a pH meter... Yet. So I couldn't verify.
Now that I'm responding to this, I wonder if the cookies would have changed the pH much?

I've had lots of dry pitches with a shake for aeration do very well in the 1.050-1 060 range, so maybe you're onto something with the pH?

 

[Saunassa]

If the Oreos went in filling and all plus the addition of the lactose would that not bump up the measured FG ?
What you are seeing on the top could be the fat from the Oreo cookie and the filling.

 

[teeWRX]

If the Oreos went in filling and all plus the addition of the lactose would that not bump up the measured FG ?
What you are seeing on the top could be the fat from the Oreo cookie and the filling.

I kind of assumed the Oreos (they went in icing and all) would contribute a lot of simple sugars that would ferment? But you know what they say about assumptions

 

[RPh_Guy]

I wonder if the cookies would have changed the pH much?

I was wondering too. Mash pH affects the enzyme action and might have added to the low fermentability.

I'm pretty sure the high FG is mostly related to the combination of other factors in the mash, not pH.

The recipe is clearly meant to be sugary sweet like other pastry stouts. I don't know why you're worried about it. ?

 

[teeWRX]

I was wondering too. Mash pH affects the enzyme action and might have added to the low fermentability.

I'm pretty sure the high FG is mostly related to the combination of other factors in the mash, not pH.

The recipe is clearly meant to be sugary sweet like other pastry stouts. I don't know why you're worried about it. ?

Maybe I shouldn't be worried? Are there commercial pasty stouts that sit in the 1.020's for FG? It really does taste quite good, just a little lower ABV than expected.

 

[RPh_Guy]

Maybe I shouldn't be worried?

Right.

Are there commercial pasty stouts that sit in the 1.020's for FG?

Yup, 20s, 30s, 40s ... Often with higher OG to add more alcohol though. Did you local brewery provide their target FG for that recipe?

It really does taste quite good, just a little lower ABV than expected.

Like I said, time to bottle and enjoy!

 

[teeWRX]

p, 20s, 30s, 40s ... Often with higher OG to add more alcohol though. Did you local brewery provide their target FG for that recipe?

Yeh I guess I meant from my starting gravity?
I'll have to bottle this one up and see how it is. Thanks for the input

 

[ChocolateBrewer]

Hey all.

All our brew days have been going so smoothly lately we decided to try something interesting, and thus have new problems. A Milk & Cookies stout, mashed with 1kg of Oreo cookies and ~450g of lactose added to the boil (recipe called for 400 but the pkg I bought was 450 so... just tossed it all in)

While all our other brews have finished slightly lower than predicted FG, this one was stuck at 1.032.

I already tried to rouse the yeast & toss in another package of Us-05, so I can only assume this one is totally done. But where did I go wrong?

The recipe was sent to us from a local brewery, it's their beer scaled down to ~5gal.

We do BIAB full volume mash, and it was done at 158F. Temp only dropped ~1degree over the 60min thanks to a couple layers of reflectix and a sleeping bag.

Targetted an adjusted version of beersmiths "stout" profile for water. I dialed the Chloride down to 240.

Pitched Us-05 dry (1pk originally), and the beer was room mates in the chamber with our Moktoberfest that fermented just fine (chamber set at 17C/63F). Our original gravity was quite a bit higher than the beersmith predicted (1.058) because I couldn't figure out how to add the 1kg of cookies to the recipe. Didn't get pure 02 for oxygenation, just a quick shake of the fermentor, same as the Oktoberfest.

After the second pack of yeast and rousing it bubbled for about 1day then quit (I had bumped up the temp to 20C/68F prior to pitching the second pack in case temp was an issue). My gravity now is ~1.028. No more bubbling is seen, there is a raft of junk floating on top of the beer that sorta looks like yeast, but I can only assume is from the Cookie? As I have a thick layer of yeast all flocc'd out at the bottom.

I'll attach pictures of the gunk currently on top. As well as my beersmith recipe and water profile to hopefully paint a better picture.

Where did we go wrong?
- Mashed too high?
- Needed pure 02?
- Or does this recipe simply contain so many adjuncts that it was doomed to end up under attenuated?
- Can I save this mess?
- Is it safe to bottle?

Any input would be helpful, cheers.

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Hey how did this turn out? Does adding the cookies straight up to the mash really work? How was head retention? About to start one this month but can’t figure out when to add the Oreos.

 

[Nubiwan]

Wouldn't the higher mash temp (158) not result in less conversion of fermentables sugars, and therefore lower attenuation? Smaller ABV?

What was your OG? Was 158 degrees the what the recipe called for? Would you not want to be in the lower 150s.

That's one complex looking recipe too. Thought my batches were tricky.

 

[teeWRX]

Hey how did this turn out? Does adding the cookies straight up to the mash really work? How was head retention? About to start one this month but can’t figure out when to add the Oreos.

Not very well, one of my worst batches to date. Too sweet, zero head retention, an oily film on top from the icing even once carb'd and conditioned in the fridge.

I'll try just the cookie part of the Oreo next time, paired with some vanilla perhaps.

 

[teeWRX]

Wouldn't the higher mash temp (158) not result in less conversion of fermentables sugars, and therefore lower attenuation? Smaller ABV?

What was your OG? Was 158 degrees the what the recipe called for? Would you not want to be in the lower 150s.

That's one complex looking recipe too. Thought my batches were tricky.

True about the mash temp, can't say i've seen such poor attenuation in other recipes mashed that high but it probably played a role.

 

[Abhishek Dewan]

Not very well, one of my worst batches to date. Too sweet, zero head retention, an oily film on top from the icing even once carb'd and conditioned in the fridge.

I'll try just the cookie part of the Oreo next time, paired with some vanilla perhaps.

Poor head retention here is due to fats from cookies. Perhaps it also caused yeast to shut down early. Other usual fat contributors are oats, coffee, chocolate or coco powder.