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General Category => General Homebrew Discussion => Topic started by: paul on December 13, 2013, 05:57:12 AM

Title: Stuck fermentation or is amber malt very unfermentable?
Post by: paul on December 13, 2013, 05:57:12 AM
I'm wondering if I have a stuck fermentation or if my beer's just done?

I used  a bunch of amber malt in a biere de garde, 15% by weight.  The rest of the grain bill was pale malt, munich malt, and abbey malt, with no crystal at all.  Mashed at 152 F.  Used Saflager 34/70, pitched two packs of rehydrated yeast for a 1.075 OG, added yeast nutrient, oxygenated as usual, fermented on the warmer side (58 F) and raised temp for the past 6 days to 70 F to try to get it to finish. It's been at 1.026 the for four days.  It really seems like I should have gotten more than 65% attenuation.

I'm wondering if the amber malt is the culprit?  Does it have a low fermentability?
Title: Re: Stuck fermentation or is amber malt very unfermentable?
Post by: dmtaylor on December 13, 2013, 12:45:18 PM
It's not the amber malt... unless perhaps you mistakenly used amber caramel malt rather than true amber malt.

Also calibrate your mash thermometer and hydrometer.  In fact this might be the most likely problem of all if you haven't calibrated your equipment recently.

Otherwise, try rousing the yeast, and add some yeast energizer, and wait a couple more weeks.  It might be done fermenting... but don't try to rush things either.
Title: Re: Stuck fermentation or is amber malt very unfermentable?
Post by: Mark G on December 13, 2013, 01:42:13 PM
Are you measuring your FG with a refractometer by any chance?
Title: Re: Stuck fermentation or is amber malt very unfermentable?
Post by: paul on December 13, 2013, 02:28:49 PM
I used a hydrometer. Didn't use amber caramel (assuming you mean cara amber?), unless the LHBS switched them!  Actually, I tasted the malt and it was definitely not a caramel malt.  The thermometer gets calibrated every batch by noting that it starts at room temperature and registers 203 F in the boiling wort (I'm at 5000 ft).  I've also swirled the carboy several times in the past few days.  Also, I added Wyeast nutrient to the boil, so it seems unlikely it would be nutrient deficient.

I'm wondering about the most proven ways to drop a few more points, assuming the fermentation is really stuck for some reason.  I've read lots of threads over the years about stuck fermentations, and many recommendations are made regarding how drop a few more points.  I haven't seen threads where people report back what worked and what didn't...yeast hulls, pitch dry yeast, pitch an active starter, etc.  Any suggestions what works best?

I have had success with unsticking a fermentation by racking the beer onto a recently flocculated yeast cake, but I don't have one handy at this point.
Title: Re: Stuck fermentation or is amber malt very unfermentable?
Post by: majorvices on December 13, 2013, 02:33:17 PM
I used a hydrometer. Didn't use amber caramel (assuming you mean cara amber?), unless the LHBS switched them!  Actually, I tasted the malt and it was definitely not a caramel malt.  The thermometer gets calibrated every batch by noting that it starts at room temperature and registers 203 F in the boiling wort (I'm at 5000 ft).  I've also swirled the carboy several times in the past few days.  Also, I added Wyeast nutrient to the boil, so it seems unlikely it would be nutrient deficient.

I'm wondering about the most proven ways to drop a few more points, assuming the fermentation is really stuck for some reason.  I've read lots of threads over the years about stuck fermentations, and many recommendations are made regarding how drop a few more points.  I haven't seen threads where people report back what worked and what didn't...yeast hulls, pitch dry yeast, pitch an active starter, etc.  Any suggestions what works best?

I have had success with unsticking a fermentation by racking the beer onto a recently flocculated yeast cake, but I don't have one handy at this point.

Sounds like you have done everything right for this style. That said, you haven't mentioned if you calibrated your hydrometer. I've had some off as much as 6 point and I imagine a 1.016-1.018 finish to this beer would not be too high. assuming what you are going for.
Title: Re: Stuck fermentation or is amber malt very unfermentable?
Post by: paul on December 13, 2013, 02:35:09 PM
If my hydrometer is that far off, then I have a hundred other batches that finished much, much lower than I actually thought!  But I'll check...
Title: Re: Stuck fermentation or is amber malt very unfermentable?
Post by: paul on December 13, 2013, 02:44:04 PM
I'll be jiggered.  My tap water is 1.002 at 60 F.  I have to go back and change all of my notes!  Not sure how much mineral content adds, but my water is pretty darn low in minerals.

However, I'm still sitting at 68% attenuation for a yeast that I've always gotten 72-77% from….correction 76-79%!  Those beers both had more crystal and/or were mashed higher than this one.
Title: Re: Stuck fermentation or is amber malt very unfermentable?
Post by: Wheat_Brewer on December 13, 2013, 02:56:04 PM
I've had some pretty good success racking the beer from the primary into the secondary with some fresh yeast from the LHBS. I've had mild success racking the beer to a secondary and taking some clean yeast from the primary and giving a gentle stir to "re-activate" the yeast.

If nothing else works I would NOT bottle carbonate for risk of bottle bombs or gushers, but if it tastes alright just RDWHAB.
Title: Re: Stuck fermentation or is amber malt very unfermentable?
Post by: Jimmy K on December 13, 2013, 03:00:00 PM
Are you certain that the hydrometer was floating and not resting on the bottom of the cylinder? All of your other procedures sound good, it's the only other thing the catches people up occasionally.
Title: Re: Stuck fermentation or is amber malt very unfermentable?
Post by: morticaixavier on December 13, 2013, 04:23:44 PM
you can perform a fast/forced ferment test to see if you have any more fermentables in there. Just draw off a sample, maybe a pint and pitch a LOT of yeast, a whole packet maybe. if that goes down to where you want it then you can confidently repitch the whole batch with lots of yeast and should see results.
Title: Re: Stuck fermentation or is amber malt very unfermentable?
Post by: beersk on December 13, 2013, 04:40:24 PM
Proven ways to fix a stuck fermentation? Amylase enzyme should do the trick. I have a stout right now that stopped at 1.022 or 1.024, krausen dropped, not happy with that. So I added some amylase, roused the yeast gently with a mix stir and the next morning it had a half inch or so of krausen. I'm hoping it drops it down to 1.016.

I've read others having success with this as well. Sometimes almost too low a final gravity.
Title: Re: Stuck fermentation or is amber malt very unfermentable?
Post by: denny on December 13, 2013, 05:00:48 PM
The abbey malt seems to be a crystal malt.  http://www.northernbrewer.com/shop/weyermann-belgian-style-abbey-malt.html  How much did you use?
Title: Re: Stuck fermentation or is amber malt very unfermentable?
Post by: tschmidlin on December 13, 2013, 07:55:00 PM
Proven ways to fix a stuck fermentation? Amylase enzyme should do the trick. I have a stout right now that stopped at 1.022 or 1.024, krausen dropped, not happy with that. So I added some amylase, roused the yeast gently with a mix stir and the next morning it had a half inch or so of krausen. I'm hoping it drops it down to 1.016.

I've read others having success with this as well. Sometimes almost too low a final gravity.
The problem with amylase is getting it to stop.
Title: Re: Stuck fermentation or is amber malt very unfermentable?
Post by: beersk on December 13, 2013, 08:06:53 PM
Proven ways to fix a stuck fermentation? Amylase enzyme should do the trick. I have a stout right now that stopped at 1.022 or 1.024, krausen dropped, not happy with that. So I added some amylase, roused the yeast gently with a mix stir and the next morning it had a half inch or so of krausen. I'm hoping it drops it down to 1.016.

I've read others having success with this as well. Sometimes almost too low a final gravity.
The problem with amylase is getting it to stop.
Yeah, this is what worries me about the oatmeal stout I used it on the other day.
Title: Re: Stuck fermentation or is amber malt very unfermentable?
Post by: tomsawyer on December 13, 2013, 09:12:58 PM
The abbey malt seems to be a crystal malt.  http://www.northernbrewer.com/shop/weyermann-belgian-style-abbey-malt.html  How much did you use?
Weyermann calls it a base malt and says you can use up to 50%.  I was thinking it sounded like a caramel malt too with the description of honey malt.
Title: Re: Stuck fermentation or is amber malt very unfermentable?
Post by: ynotbrusum on December 13, 2013, 09:19:45 PM
Any chance the yeast are pooped?  Just a thought.  Mort's fast ferment test will establish that, if you have another packet of 34/70 to pitch.  I have found just the opposite with repitched 34/70 (it chugs it lower than 1.010 on some lager batches), but you never know for sure on dry yeast viability and performance...
Title: Re: Stuck fermentation or is amber malt very unfermentable?
Post by: paul on December 14, 2013, 05:34:10 AM
I'm not sure if I used Weyermann or Castle Abbey malt, but I thought of it as a darker munich/aromatic malt, not crystal.  I used 7% abbey malt, so not that much.  Oh, and here's some information on Abbey malt. In this case 33% Abbey malt didn't hurt attenuation at all: http://discussions.probrewer.com/showthread.php?20540-Feedback-on-new-Weyermann-Belgian-Malts.

Hydrometer was definitely floating…that I checked.

Pooped yeast is the only possibility that remains. A forced ferment test makes sense.  But I could waste a pack of yeast on the test, then have to buy another two to pitch in the beer.  Seem like i could just pitch two in the beer?  Or is there a downside to that?
Title: Re: Stuck fermentation or is amber malt very unfermentable?
Post by: jeffy on December 14, 2013, 02:44:37 PM
I'm not sure if I used Weyermann or Castle Abbey malt, but I thought of it as a darker munich/aromatic malt, not crystal.  I used 7% abbey malt, so not that much.  Oh, and here's some information on Abbey malt. In this case 33% Abbey malt didn't hurt attenuation at all: http://discussions.probrewer.com/showthread.php?20540-Feedback-on-new-Weyermann-Belgian-Malts.

Hydrometer was definitely floating…that I checked.

Pooped yeast is the only possibility that remains. A forced ferment test makes sense.  But I could waste a pack of yeast on the test, then have to buy another two to pitch in the beer.  Seem like i could just pitch two in the beer?  Or is there a downside to that?
With the fast ferment test, any yeast will work.  Even a packet of bakers yeast, from what I've heard.
Title: Re: Stuck fermentation or is amber malt very unfermentable?
Post by: paul on December 14, 2013, 07:07:20 PM
Bread yeast does sound like a good idea for the test.  Thanks!
Title: Re: Stuck fermentation or is amber malt very unfermentable?
Post by: hubie on December 15, 2013, 04:18:54 PM
Is there a decent way to calculate the anticipated fermentability?  If I understand what is typically done with calculators is that they calculate the OG then just multiply by some attenuation factor for that yeast strain and don't take into account how fermentable each component is.  Is my understanding correct?
Title: Re: Stuck fermentation or is amber malt very unfermentable?
Post by: erockrph on December 16, 2013, 09:02:10 AM
Is there a decent way to calculate the anticipated fermentability?  If I understand what is typically done with calculators is that they calculate the OG then just multiply by some attenuation factor for that yeast strain and don't take into account how fermentable each component is.  Is my understanding correct?

I think there are way too many factors to consider in order to nail it down better than a WAG. Mash temp and fermentation temp/schedule play an important role, as well as fermentability of various ingredients. And who's to say that one maltster's C-60 is going to have the same fermentability as another's? I think you'd have a much easier time herding cats than trying to develop a FG calculator that's going to get you within more than a few points.

I think the only thing I'd like to see calculators do better is handle 100% fermentable ingredients (like sugar) better. But I just add them to the recipe last and see what the predicted FG was before they went in to get a better estimate of the expected FG.