Stuck Fermentation, help please.

[brew_potter]

I am very new at this, but am having a great time reading, brewing and drinking.
I have two primaries going right now and fermentation has stopped with the FG still too high. I'll only explain one of them since the solution will probably be the same for both.
I brewed the Power Pack Porter kit from Midwest on 2/19 and everything went well. Didn't have any problems and was very careful with sanitation. I cooled the wort to 67 with an IC and pitched dry yeast. I got active fermentation by the next morning with plenty of bubbles in the airlock and a nice krausen on top. The carboy was in my basement and was a constant 63deg. The yeast packet said 60-70 was the ideal temp., if I remember correctly. OG was 1.068 before pitching (target 1.063 - 1.067). I waited until 3/11 to take another reading and got 1.023 (target FG 1.102-1.015). Since it had been three weeks I decided to warm up the carboy to see if I could jump start the yeast. I used an aquarium heater in a tub of water and brought the temp up to 72. I waited until tonight (3/19) to take another reading and got 1.023 again.
I tasted the beer after taking both readings and it still tastes a little sweet, not terribly so, but sweet. No signs of infection so far.
So, what do I do?
Should I stir to agitate the trub? Pitch more yeast? Add a yeast nutrient?
Thanks in advance!
Ryan

 

[djfriesen]

I'm assuming this was an extract kit? What was your process? Depending on when you added the LME, you could have carmelized some of the sugar, causing it to be unfermentable. Your other attempts seem good, and your beer might be finished. Pitching more yeast won't help it, as there is isn't anything else for it to eat.

Something like bean-o might work to break down the unfermentable sugars into fermentable molecules, but I have heard that results with that are unpredictable. If it's done, it's done, and you'll just end up having a slightly lower ABV and more body, which won't be too bad for a porter. Also, post a detailed recipe and process, and maybe someone else can pick something out that I'm unaware of.

 

[brew_potter]

Thanks DJ.
It was an extract kit.
Brought 5g of spring water to 158deg.
Steeped the grains for 25 minutes at 156-158.
Removed grain bag.
Brought to a boil and turned of the propane burner.
Added the LME, stirred and turned the heat back on.
Brought to a boil and added 1.5oz bittering hops.
Boiled 45 minutes.
Added IC to brewpot to sanitize.
Boiled 15 more minutes.
Added 1.5oz. aroma hops with 2 min to go.
Cooled from 210 - 82 in 8 minutes.
Poured the wort through a mesh kitchen colander and into a carboy.
Added .75 gallon of spring water to carboy to bring volume to 5g total.
Aerated by swirling for 30-45 seconds.
Pitched yeast at 67deg.
Let it sit and beerify.

 

[djfriesen]

Well, the only thing that sticks out is adding the LME early. Research late extract addition: you're basically adding the LME very late in the boil, or even at flameout to reduce carmelization/scorching.

I have read of extract batches having the tendency to stick around 1.020, but I have also read rather knowledgeable brewers refuting it. Seems that, at some point, extract products (because of the process used by the maltster?), commonly caused a stuck fermentation at around 1.020. However, I have also read that advances in technology have lessened this effect. I imagine the freshness of your LME would be the likely culprit, if this is indeed the case.

This could be your issue, but since I have little personal experiance with extract brewing, I can't speak from any personal experience.

You might try posting this question in the Extract Brewing section, and see if you can get more informed advice.

 

[House12]

Because you did a 5 gallon boil, late extract addition is really not essential.

Judging by your numbers, you have an apparent attenuation of 67%. Depending on thd yeast you pitched, that's really not so far off. To get the final gravity the recipe called for, you would need apparent attenuation of about 80%. In order to answer your question, we'd need to know what yeast you're using. Since you said 'pack', I'm assuming it's a dry yeast, and I'd guess it's probably US 04. If so, 70% attenuation is expected, and your FG is not too far off at all.

Adding nutrient, air, etc. is important for yeast growth during the lag. Now, all you can do is rouse the yeast and warm it a bit. If it's an english strain you used, it'll be tough to overcome it's love of flocculation.

 

[OkashiiBrew]

Aerated by swirling for 30-45 seconds could be part of it too. My shake and ferment batch attenuated at 1.016 and my oxygenated batch finished at 1.013. I did shake for a full five minutes and ran the oxygen for 1 minute. I am never going to shake an ferment again. Heck, I can't even do a full hour of P-90x so o2 is the way to go. Efficiency is applied laziness

 

[JLem]

have you checked your hydrometer in plain water? 1.023 does seem a bit high, even for an extract brew, which can sometimes finish out at 1.020.

It is possible that it is not stuck, but done. However, if your hydrometer checks out OK (make sure to correct for temperature), I might try rousing the yeast gently and warming the beer up some - if you have a heating pad, you can wrap it around the fermenter. I use a bungie cord to hold it in place. You might get a couple more points out of it.

 

[brew_potter]

Thanks for the advice all.
I went to the LHBS today and got two new hydrometers and a gallon of distilled water. My old hydrometer read 1.003 at 70, so 1.004 adjusted. The new ones read 1.002 and 1.005 adjusted. Ug, what's the point of a hydrometer if it's that far off?
That means my reading of 1.023 was really 1.020.
I just gently stirred the wort with a sterilized spoon and plan to give it a few days and take another reading. I also turned up the aquarium heater to about 76deg.

In the future I plan to make yeast starters and will get an oxygen system.

 

[JLem]

Thanks for the advice all.
I went to the LHBS today and got two new hydrometers and a gallon of distilled water. My old hydrometer read 1.003 at 70, so 1.004 adjusted. The new ones read 1.002 and 1.005 adjusted. Ug, what's the point of a hydrometer if it's that far off?
That means my reading of 1.023 was really 1.020.
I just gently stirred the wort with a sterilized spoon and plan to give it a few days and take another reading. I also turned up the aquarium heater to about 76deg.

In the future I plan to make yeast starters and will get an oxygen system.

Hydrometers, like all measurement instruments, need/should be calibrated. You now know the error on your hydrometer. It is useful even though it is not spot-on accurate, and you can get an accurate measurement, as long as it is consistent and you adjust for the error.

At 1.020, I think this beer may very well be done. 1.020 is not uncommon with extract batches and I think even more so with something like a porter or stout. You may get another point or two, but don be surprised (or disappointed even) if it stays where it's at.

 

[brew_potter]

I let the porter sit another few days after stirring and warming it up to 75deg and the sg dropped a point, so I will consider it done and bottle it this weekend.

I also have a coopers Belgian Tripel going and the sg is at 1.030 with a target of 1.017-1.020. It has been in primary since 2/26. I stirred it and warmed it to 85 just like the porter a week ago, no further drop.

Here is the instruction sheet:
http://www.ldcarlson.com/public catalog/Brewers Best Recipes/1044.pdf

I followed the instructions carefully and my og was 1.088. I tasted this tonight after taking a reading and it tastes very sweet.

Any ideas on how to drop the gravity further?

Thanks!

 

[muthafuggle]

I let the porter sit another few days after stirring and warming it up to 75deg and the sg dropped a point, so I will consider it done and bottle it this weekend.

I also have a coopers Belgian Tripel going and the sg is at 1.030 with a target of 1.017-1.020. It has been in primary since 2/26. I stirred it and warmed it to 85 just like the porter a week ago, no further drop.

Here is the instruction sheet:
http://www.ldcarlson.com/public catalog/Brewers Best Recipes/1044.pdf

I followed the instructions carefully and my og was 1.088. I tasted this tonight after taking a reading and it tastes very sweet.

Any ideas on how to drop the gravity further?

Thanks!

1.088 is a pretty high Starting Gravity. (I mean it's fine for a trippel, but that's a big number). When you brew anything high-gravity like that (I'll define everything with a SG of over 1.070 as a high-gravity beer, but definitions vary) there are some special considerations to think about. Yeast pitching rates are important, oxygenation is really important. The ferment-ability of your extract is probably the culprit here, especially if you were using LME of unknown freshness. As LME oxidizes and/or ages it becomes less and less fermentable. With a normal beer of around 1.050, older LME can become the dreaded 1.020 FG of extract brewing. Using 2/3rds more extract than that will really expose lower-fermentability by leaving you with a higher FG.

If you really want to know more about this, the absolute best brains in brewing (Palmer and Zanischeff) go through this in exhaustive detail on their Brew Strong podcast about brewing high-gravity beers (part 1 of 4 has the section on fermentability)

 

[JLem]

^ what muthafuggle said.

High gravity beers can be tricky, more so when using a lot of extract. For this beer you might consider making a yeast starter and pitching it when active - the healthy, active yeast might be able to chew through the beer some more (assuming there are fermentable sugars still in there). You could even go with a lager strain since they can ferment some of the longer sugars that ale strains cannot.

Basically, the question is whether your yeast pooped out before they could finish the job because of unfavorable conditions (low oxygen, poor nutrients, high alcohol, etc) or whether the base wort was high in long-chain, unfermentable sugars. If the former, you can still save this beer with a healthy repitch. If the later, there's not much you can do unless you want to pitch some Brett and make yourself a funky tripel. I suppose there's the idea of adding enzymes to make it more fermentable, but I have zero experience with that (and quite frankly, am very wary of that technique)