Cap Management on a Big, Slow Fermentation

[BrewDrinkRepeat]

So this blueberry mel has gone from 1.160 to 1.102 in a little over a week. Not terribly slow, but at this point I'm not sure what to do about the cap as I thought it would be further along at this point.

Time-wise this is about the time I would stop stirring on a regular mead, but there are 12# of blueberries in there.

I can keep stirring / punching the cap two or three times a day until I get further along, I can stop cap management but leave the fruit in there, or I can get the mead off of the fruit and then just let it do its thing for however long it takes to reach FG (which I'm hoping will be somewhere around 1.020 when all is said and done, although I'm not sure the D47 is going to get me there).

Which is the best option here, do you think?

 

[loveofrose]

I'm afraid it's not the fruit cap that is the problem. The problem is your SG. SG of 1.16 is way too high for any yeast. Anything above 1.14 is considered far too great for even the most robust yeast. D47 is definitely going to crap out on you. You will likely need to dilute this batch to get it going again. Also, I would add potassium carbonate to buffer the extremely acidic pH with blueberries. I'll help further, but I need you to answer some questions:
What nutrients did you use (if any)?

Are you sure the SG was 1.16?


Better brewing through science!

 

[BrewDrinkRepeat]

Well, I have a tendency to mess things up, so...

I did overshoot my OG a bit (I was targeting 1.150 - 1.155), but let me explain where I came up with that: I'm counting on the 12# of blueberries to eventually contribute about 1.2 gallons of water, reducing the gravity by roughly 0.025 (1.125 being my "real" target OG). Formula for this was from Steve Piatz's mead book.

1.125 was based on the D47 tolerance (listed as 14% but I've seen it go higher), as well as my desired FG (~1.015, the top end of medium/semi-sweet)

Nutrients: I made a 2:1 SNA mixture (DAP : Fermaid K), and pitched 2g every other day. I've been stirring with a wine whipper three times per day to aerate, degas and break up the cap.

What I'm worried about in regards to the cap is that I'm told it's bad to leave them floating for too long (dries out the fruit, prevents degassing, temperature buildup and yeast getting caught in the cap where they can't get their work done), but also I don't want to aerate after a point where it could oxidize the mead. I don't mind continuing to stir three times a day for as long as I have to, but I want to be sure that's the right thing to do (and at what point it's advisable to stop).

 

[loveofrose]

Well, I have a tendency to mess things up, so...

I did overshoot my OG a bit (I was targeting 1.150 - 1.155), but let me explain where I came up with that: I'm counting on the 12# of blueberries to eventually contribute about 1.2 gallons of water, reducing the gravity by roughly 0.025 (1.125 being my "real" target OG). Formula for this was from Steve Piatz's mead book.

1.125 was based on the D47 tolerance (listed as 14% but I've seen it go higher), as well as my desired FG (~1.015, the top end of medium/semi-sweet)

Nutrients: I made a 2:1 SNA mixture (DAP : Fermaid K), and pitched 2g every other day. I've been stirring with a wine whipper three times per day to aerate, degas and break up the cap.

What I'm worried about in regards to the cap is that I'm told it's bad to leave them floating for too long (dries out the fruit, prevents degassing, temperature buildup and yeast getting caught in the cap where they can't get their work done), but also I don't want to aerate after a point where it could oxidize the mead. I don't mind continuing to stir three times a day for as long as I have to, but I want to be sure that's the right thing to do (and at what point it's
advisable to stop).

I see your logic on the blueberries diluting the batch, but it doesn't matter because it will happen too late. Your yeast are already stressed to the max. Raising the temperature (which I hope is below 70 F) is not an option because D47 will throw lots of of fusels (If it hasn't already due to high SG).

My suggestion would be the following:
1. Add 3/4 TBSP potassium carbonate. Blueberries can be really acidic and cause stalled ferments all alone.
2. Add 0.5 gallon of water to dilute the gravity a bit. Bright side is you will have more mead!
3. Keep stirring until you hit 1.04.

Try all that and see if it works. If it doesn't, I'll give you the nuclear option.





Better brewing through science!

 

[skadalajara]

Subscribing to hear what the "nuclear option" is.

 

[noblesquirrel]

I'm afraid it's not the fruit cap that is the problem. The problem is your SG. SG of 1.16 is way too high for any yeast. Anything above 1.14 is considered far too great for even the most robust yeast. D47 is definitely going to crap out on you. You will likely need to dilute this batch to get it going again. Also, I would add potassium carbonate to buffer the extremely acidic pH with blueberries. I'll help further, but I need you to answer some questions:
What nutrients did you use (if any)?

Are you sure the SG was 1.16?


Better brewing through science!

That's not true. I've had plenty of meads and know plenty of folks who have started 1.160. It's not easy, but it is certainly not outside the scope of the yeast. I've gotten 115 points out of 71b from that OG. Good oxygenation and degassing practices are necessary, but it's more than doable.

 

[BrewDrinkRepeat]

I'm assuming the nuclear option is champagne yeast (which would be my contingency plan if the D47 craps out on me), but I'm curious as well.

I didn't realize yeast would get stressed by so much sugar, I thought they would just enjoy the buffet and convert/metabolize what they could until the alcohol level reached their tolerance (which for D47 is supposedly 14% but I've seen it go several points higher). In addition to being my first melomel with real fruit, it's also the first time I've tried to do such a high gravity fermentation -- thought I was being smart trying to account for the yeast tolerance in relation to FG.

I don't have a pH meter yet (I'm about to order one, probably the Hach) but it certainly doesn't taste overly acidic. Granted there is still an awful lot of sugar in there... and while the alcohol is starting to become noticeable (it's at about 8% right now, give or take) I don't taste any fusels or other high alcohols. I have no illusions that this one will be ready to drink any time soon; the plan is to serve it @ Thanksgiving next year.

If I did need to add something to raise the pH I don't have any potassium carbonate on hand, but I do have calcium carbonate if I needed to use that.

Good oxygenation and degassing practices are necessary, but it's more than doable.

I've been degassing three times a day (four once or twice when I happened to be around to do it), and I'm using a wine stirrer on the high setting on the drill which creates a massive vortex almost to the bottom of the bucket.

Since I'm still nowhere near FG should I keep doing more SNAs as well? I've already done four (one every other day), but I have plenty of DAP and Fermaid-K lying around.

Maybe I'm worrying too much about this one... I just don't want to ruin it via oxidation or underattenuation.

 

[loveofrose]

That's not true. I've had plenty of meads and know plenty of folks who have started 1.160. It's not easy, but it is certainly not outside the scope of the yeast. I've gotten 115 points out of 71b from that OG. Good oxygenation and degassing practices are necessary, but it's more than doable.

I'm going to need proof on taking 1.160 to 1.000. That's 21% and not trivial. Especially with a yeast that has a 14% ABV tolerance. Sure, I've seen yeast push and extra 2% or so, but not 7%.

Your 115 points with 71B is 15.1% ABV with a 14% ABV rated yeast. He's talking about 160 points! Even if you were happy with FG of 1.02 (140 points), that's still 18.3% with a 14% yeast. Good luck with that.

In addition, it will be many years before it would be drinkable due to stressed yeast making lots of fusels.



Better brewing through science!

 

[loveofrose]

I'm assuming the nuclear option is champagne yeast (which would be my contingency plan if the D47 craps out on me), but I'm curious as well.



I didn't realize yeast would get stressed by so much sugar, I thought they would just enjoy the buffet and convert/metabolize what they could until the alcohol level reached their tolerance (which for D47 is supposedly 14% but I've seen it go several points higher). In addition to being my first melomel with real fruit, it's also the first time I've tried to do such a high gravity fermentation -- thought I was being smart trying to account for the yeast tolerance in relation to FG.



I don't have a pH meter yet (I'm about to order one, probably the Hach) but it certainly doesn't taste overly acidic. Granted there is still an awful lot of sugar in there... and while the alcohol is starting to become noticeable (it's at about 8% right now, give or take) I don't taste any fusels or other high alcohols. I have no illusions that this one will be ready to drink any time soon; the plan is to serve it @ Thanksgiving next year.



If I did need to add something to raise the pH I don't have any potassium carbonate on hand, but I do have calcium carbonate if I needed to use that.







I've been degassing three times a day (four once or twice when I happened to be around to do it), and I'm using a wine stirrer on the high setting on the drill which creates a massive vortex almost to the bottom of the bucket.



Since I'm still nowhere near FG should I keep doing more SNAs as well? I've already done four (one every other day), but I have plenty of DAP and Fermaid-K lying around.



Maybe I'm worrying too much about this one... I just don't want to ruin it via oxidation or underattenuation.

Potassium carbonate is much better for mead. Not only does it buffer pH, but it provides potassium which is limited in honey. Potassium also improves the alcohol tolerance of the yeast thus making them less stressed.

Degassing once a day is plenty. What do you want for final gravity?

In the future, step feeding is a much better practice. Start with 1.12 and let it go dry. Add honey to your desired sweetness and let the yeast ferment again. Repeat until the yeast give up and you are holding at your desired gravity. This has the advantages of not stressing your yeast and never producing stupidly sweet mead.





Better brewing through science!

 

[BrewDrinkRepeat]

I'm going to need proof on taking 1.160 to 1.000. That's 21% and not trivial. Especially with a yeast that has a 14% ABV tolerance. Sure, I've seen yeast push and extra 2% or so, but not 7%.

Your 115 points with 71B is 15.1% ABV with a 14% ABV rated yeast. He's talking about 160 points! Even if you were happy with FG of 1.02 (140 points), that's still 18.3% with a 14% yeast. Good luck with that.

Actually no, I'm looking for a final gravity around 1.015 - 1.020, and I was counting on the blueberries adding enough water (at some point) to reduce the gravity by about 20 points or so over the course of fermentation.

When I did all the initial calculations I was targeting the yeast to poop out around 14%. Since 14% = 1.107, my target OG was 1.122 (without fruit) to leave 1.015; factoring in the water I assumed the fruit would add** that brought me up to approx. 1.150, and then I overshot and ended up with 1.160.

(** I knew the blueberries wouldn't give up their water immediately, but I figured they'd have given up quite a bit by now especially with such vigorous stirring. I guess not.)

Degassing once a day is plenty.

I've been doing it three times a day more because of the fruit cap... those blueberries end up back at the top within a few minutes of stirring everything up anyway. Next time I use real fruit I think I'm going to bag 'em and weigh them down.

In the future, step feeding is a much better practice. Start with 1.12 and let it go dry. Add honey to your desired sweetness and let the yeast ferment again. Repeat until the yeast give up and you are holding at your desired gravity. This has the advantages of not stressing your yeast and never producing stupidly sweet mead.

Cool, I think I will try that next time!

 

[noblesquirrel]

I'm going to need proof on taking 1.160 to 1.000. That's 21% and not trivial. Especially with a yeast that has a 14% ABV tolerance. Sure, I've seen yeast push and extra 2% or so, but not 7%.

Your 115 points with 71B is 15.1% ABV with a 14% ABV rated yeast. He's talking about 160 points! Even if you were happy with FG of 1.02 (140 points), that's still 18.3% with a 14% yeast. Good luck with that.

In addition, it will be many years before it would be drinkable due to stressed yeast making lots of fusels.



Better brewing through science!

I think you're missing everything that I was commenting on. The OP wasn't at 1.00, he went from 1160 to 1100 or so. I have no idea what you're even commenting on at this point as it's not related. My comment was directed at you stating that 1.160 was too high of a gravity, which is just not true. To get back to 1020 or drier, perhaps. But not if your goal is a big jammy mead. yeast health and pitching rates are important and a lot can be coaxed out of these strains.

 

[loveofrose]

My comment was directed at you stating that 1.160 was too high of a gravity, which is just not true. To get back to 1020 or drier, perhaps.

He wants 1.02; therefore, 1.16 is too high.

 

[BrewDrinkRepeat]

1.086 this morning. Nice acidity, noticeable alcohol (of course) but not boozy or fuselly.

Still making slow, steady progress...

 

[BrewDrinkRepeat]

1.072 just now... Considering the current gravity it's surprisingly not cloyingly sweet (the alcohol, tannins and acidity are balancing it quite nicely right now... hopefully that continues when it gets down to the target FG!).

I haven't diluted with any water yet, but I think I'm going to. Fermentation was already slow and it seems to have slowed a bit more over the last 4-5 days.