Fermentation Rejuvination

[Estrada]

See what I did there? Anyway, seems my fermentation is a but stuck. Took a gravity reading last week and tonight with no movement (only about half way to the end goal). I've tried warming up a few degrees and have given some gentle swirls, however, to no avail. Any thoughts?

Also, I pitched with liquid yeast. If I needed to boost activity, could I drop in a packet of dry, or is that a no no?

On the plus side, the beer tastes good.

 

[Homebrew35]

I suggest making a starter with 24oz of wort. Cooled and then pitch with a dry pack of yeast, let it get going, high Kroysen. 8-12 hrs or until it has a half inch of foam. Dump it all in.

Need more details but this is my suggestion sight un-seen.

Was this all grain/extract. Mash temp, starter if any and the technique. Wort temp at pitch. How old was the liquid yeast?

 

[PLOVE]

(only about half way to the end goal).

By half-way, do you mean you started at 1.06 and you're down to 1.03, or you're trying to get to 1.01, but you're at 1.02. I ask, because the first is symptomatic of a seriously stuck ferm, the second could be related to process. What was your mash temp, etc.?

P

 

[RM-MN]

Are you using a refractometer to read the gravity? With alcohol in the beer, they read high. You can use a correction table but for the best accuracy, use a hydrometer.

 

[Estrada]

Thanks.

It's an extract kit for a milk stout.

The liquid yeast I used was British Ale Yeast WLP005 and I used it a few days after I received it (stored in the fridge, warmed to room temp prior to use).

Mash temp: 175. Cooled the wort to 80

I'm using a hydrometer. The original gravity reading was 1.041, currently at 1.022, and I'm shooting for 1.007.

Did not rack to a secondary, the entirety of the fermentation has been in the primary.

 

[antony]

My milk stouts rarely finish below 1.020; the lactose is unfermentable. I think you're probably fine.

I'm curious about your mash temp though, maybe someone else can comment on that. It seems a bit high to me. I usually mash b/w 148-153, then mash out closer to 170. If I remember correctly, mashing that high will produce some unfermentable sugars as well.

All in all, I think your milk stout's good to go.

 

[schokie]

I think by mash temp the OP meant grain steep temp since it's an extract recipe. That being said, 175F might be a bit high for steeping. That can cause some undesired flavors to come through. But it shouldn't affect fermentability. Though since you said it tastes good, you can probably ignore everything I just said.

What's the recipe? Is 1.007 the expected final gravity? That would give you an attenuation of 82%, which is a bit high for that yeast. I'd expect more about 1.012 or so. Maybe even higher if you used lactose like antony mentioned.

If it is truly stalled and you tried the swirl and bump the temp method, then do what Homebrew35 suggested.

 

[Estrada]

Yeah, thanks, it is grain steep temp. I originally thought the same, but ended up going with what the kit called for.

The recipe is the Midnight Milk Stout from Monster Brew (came with both liquid and dry malt, lactose, grains). Yeah, you're right on, the FG should be 1.007 (again, going off the recipe).

Might be a dumb question, but does mixing the yeast strains matter, the liquid to dry?

Thanks all for the help!

 

[schokie]

There's no problem mixing and matching like that. The only real difference between dry and liquid yeast is the dry is dehydrated for storage. Once they hit the wort they act the same.

Also, most of the flavors are produced early in the fermentation, so for the most part it doesn't matter what yeast you use now. Just pick one that attenuates well.

 

[Estrada]

Awesome, thanks.

Starting to feel like that 5 year old who keeps asking why, but just thought of one other question. What's the rationale behind extracting a sample to add in the yeast, and add back into the primary, as opposed to just adding the yeast directly into the primary?

 

[schokie]

Don't worry about the questions; that's what's great about this forum. And when I answer your question incorrectly someone else will correct me and we can both learn!

It seems like the krausening instructions weren't perfectly clear. Don't extract a sample, instead use fresh extract boiled in water. Once that's cooled to pitching temps (60-75F), pitch the yeast. When you see signs of fermentation, pour the whole thing into your primary. It's similar to making a starter, but instead of growing yeast you're just trying to kick start their activity.

If you don't have any more extract you can use sugar. Extract is preferred though. Your wort by now is low on fermentable sugar and alcohol, neither situation is good for yeast. So you have to make another environment for them that's friendly to convince them to get into fermentation mode before introducing then to the harsh environment of your mostly-fermented beer. Just use about 50g of extract in 500ml water. A normal starter would be bigger, but you don't need much for your purposes here. You should see activity within a day. Give it another 12-24 hours for high krausen.

 

[Homebrew35]

Osmotic shock can kill dehydrated yeast. You need to re-animate the yeast with warm water, not even wort. Read some yeast manufactures websites. Some say this, I think wine makes use a specific liquid to re hydrate dry yeast.

 

[Homebrew35]

Yes what "Schokie" said: thanks for the clarification. My quoting skills are lacking.