Chocolate Milk Stout - Stalled Fermentation

[Horners]

Morning all

I have read the many threads on rebooting a stalled fermentation and I will implement some of the usual tactics tonight. But as I sit here shackled to the desk and my mind wanders from a tedious report, I figured it would be a better use of my time asking some questions on the HBF. Background is as follows, brew is an AG chocolate milk stout OG 1050ish, Safale 04 pitched dry at say 21C, femerntation temperature apparently set to 20C, off to a flyer for a few days, now 10 days in SG is stuck at c1030.

This is my first stuck ferment but there were a number of 'new' factors associated with this so I thought I would check with forum and see if any of them throw up any obvious explanations:

1. First use of lactose - obviously this should result in a higher FG beer but not this high. Other than being unfermentable I'm assuming lactose doesn't otherwise inhibit the yeasts performance?

2. First use of cacao nibs - I soaked them in about 100ml of vodka to sterilise and chucked the whole lot in loose. Surely this cant affect things.

3. First use of stainless steel fermentor. Brewbelt is attached around lower part of fermentor. Could all the heat just be being conducted away and notwithstanding that the inkbird is showing 20C the wort is actually closer to ambient temperature which is pretty cold at night. Also probe is attached (insulated) to outside of FV which has never been a problem with plastic buckets.

I think first step tonight will be to open it up and get a thermometer down in the wort but it is frustrating being sat here knowing the wort is not progressing.......

 

[GerritT]

Underpitching could be a thing, hot maisching too, how big is the batch and at what temperature did you maisch?

 

[Horners]

Underpitching could be a thing, hot maisching too, how big is the batch and at what temperature did you maisch?

Batch was 25L, mash temp 67.5

 

[phildo79]

What temp was the brew when you took the OG?
How much dry yeast did you pitch?

I always use Safale 04 due to the fact I got a great deal on a 500g packet. I've never had any problems with it. I always pitch approx. 20g per batch (always around 4 or 5 gallons) and find that the ferment is super fast; sometimes complete within 3 days.

 

[Horners]

Temperature for OG reading would be ambient and correlated with refractometer. Yeast could be underpitched, I would have used the 11 or so grammes in one packet but not been a problem before for beer of this strength.

 

[Horners]

So temp of wort is between 19 and 20 so roused, pitched new pack of s04 and upped the inkbird a couple of degrees.. we will see

 

[phildo79]

We're clutching at straws here but did you aerate the batch after you pitched the yeast? I've noticed quite a difference in fermentation times depending on this.

It could be a bad packet of yeast but unless it's quite old, that seems unlikely.

How do you store your yeast? I keep mine in the fridge and it works really fast. However, I put it in the freezer once and the whole fermentation process was really strange. It took longer than I expected, there was no activity in the airlock and hardly any krausen. I actually thought fermentation hadn't properly begun and was shocked when I measured the gravity.

 

[Horners]

Yeast generally kept in brew fridge - but who knows first batch may have sat in a box in tge brewcave with temps reaching 40c in the heatwave over summer.

 

[Simonh82]

What was your recipe? How much lactose did you use and how much dark malt? Can you check the accuracy of your thermometer?

I'm sure you are right that it shouldn't stop this high but I have found lots of dark grains can have a big impact on the FG.

 

[Horners]

Happy with thermometer - ag

rees with inkbird. Recipe in attachef pic...

 

[Horners]

Update - no airlock activity (this one did bubble away on initial ferment) but fingers crossed seems to have moved in right direction now at 1026.

Its a craftybrews prepacked recipe they reckon 1017 target gravity albeit think my OG was a few points higher. Not sure about taste out of jar though - its going to end up being on the cacao longer than anticipated and tastes more like chocolate than coffee.

Patience etc.

 

[Slid]

Yeast generally kept in brew fridge - but who knows first batch may have sat in a box in tge brewcave with temps reaching 40c in the heatwave over summer.

This may be a clue - could you expand on this please? The guys here know their stuff, but they do need the fullest information to help most effectively?