First Stuck Fermentation

[tgolanos]

As the title says, I just experienced my first stuck fermentation. It's an Irish Red, OG 1.046, predicted FG 1.010. I made a starter using WLP007. Fermentation took off within expected timeframe, but died down quickly. I didn't think much of it until today (one week after fermentation started) when I took a hydrometer reading that read 1.023.

My best guess is that my fermentation temp of 18°C was actually lower than I though and the yeast dropped out. I tried rousing the yeast cake, but that didn't seem to move it since it was caked like a mofo. I didn't want to risk oxidising, so I ended up racking the beer to another fermenter, making sure to suck up as much of the yeast as I could along the way. I've left it out of my cool bag to warm up, as well.

Now we wait...

 

[ncbrewer]

Hopefully, the warming and rousing will help some. If not, it still might be an ok beer, even though not what you were going for. How did the sample taste?

 

[tgolanos]

The sample tasted great, like one I made last year, so that's a positive sign. I allowed it to rise to room temp (24°C). When I shined a flashlight into the fermenter I could see some light bubbling. Could be CO2 offgassing or it could be yeast activity, or both.

I'll check it again on Wednesday evening, but I feel hopeful. Worst case, I'll bottle it up and have a good 3.5%er.

 

[tgolanos]

I pulled a sample this evening. It's down to 1.019, so transfer and rousing caused some sort of action. I'm going to keep it at room temperature and rouse it over the next few days to try to drop it a few more points.

 

[RM-MN]

As the title says, I just experienced my first stuck fermentation. It's an Irish Red, OG 1.046, predicted FG 1.010. I made a starter using WLP007. Fermentation took off within expected timeframe, but died down quickly. I didn't think much of it until today (one week after fermentation started) when I took a hydrometer reading that read 1.023.

My best guess is that my fermentation temp of 18°C was actually lower than I though and the yeast dropped out. I tried rousing the yeast cake, but that didn't seem to move it since it was caked like a mofo. I didn't want to risk oxidising, so I ended up racking the beer to another fermenter, making sure to suck up as much of the yeast as I could along the way. I've left it out of my cool bag to warm up, as well.

Now we wait...

This moving of the beer was probably counter to both of what you wanted. It is much easier to oxidize beer by moving it and you left a lot of the yeast that you need for fermentation to reduce the FG behind. Warming the beer was the right move though as it encourages the yeast to complete the ferment. Most of the time the yeast brings the beer to the desired FG very quickly but occasionally it gets slowed way down. That's when it tries your patience. I'd leave the beer where it is warm for another week to 10 days before taking another hydrometer sample.

 

[FermentedCulture]

Did you mash high and if you can check your mash thermometer's calibration.

 

[tgolanos]

Did you mash high and if you can check your mash thermometer's calibration.

As far as I can tell, my thermometer was calibrated. It was a new one, but I tested it first in boiling water. It read 100°C in the water, so I can only assume it was accurate in reading my mash temp of 66°.

This moving of the beer was probably counter to both of what you wanted. It is much easier to oxidize beer by moving it...

I realize there was a risk of oxidation in transferring to another fermenter. I couldn't get the yeast back into suspension after warming it up (007 is something else!), so I thought transferring it might be worth trying. Luckily, my last hydrometer sample has zero hints of oxidation or other off-flavors, so I might've lucked out. The real test will be the next one I pull in a few days' time.

...and you left a lot of the yeast that you need for fermentation to reduce the FG behind. Warming the beer was the right move though as it encourages the yeast to complete the ferment. Most of the time the yeast brings the beer to the desired FG very quickly but occasionally it gets slowed way down. That's when it tries your patience. I'd leave the beer where it is warm for another week to 10 days before taking another hydrometer sample.

Leaving too much yeast behind was definitely something I was worried about. I tried to siphon up as much as I could and even scooped a fair amount into the new fermenter. I plan on leaving it until next weekend before I decide what to do - bottle or buy a neutral yeast and see if it drops any more.

As always, all the advice and help is much appreciated.

 

[RM-MN]

I realize there was a risk of oxidation in transferring to another fermenter. I couldn't get the yeast back into suspension after warming it up (007 is something else!), so I thought transferring it might be worth trying. Luckily, my last hydrometer sample has zero hints of oxidation or other off-flavors, so I might've lucked out. The real test will be the next one I pull in a few days' time.

Oxidation would take quite a while to be very noticeable so you sample would probably not be definitive. I'd say there is only a small chance of oxidation although the Low Dissolve Oxygen fanatics would say otherwise.

 

[FermentedCulture]

For what it's worth the decades ago when scientists were characterising this yeast they noted that it (whitbred b/wlp007) stratifies wort during the most active part of fermentation - readings near the bottom had less sugar than reading near the top. It's probably not what made this reading though considering it had 1 week of contact time. Maybe it was just premature flocculation, afaik wlp007 doesn't really use a lot of maltotriose.

 

[tgolanos]

Just thought I'd post an update on this one. After 10 days of carbonation at 22°C, this is the product. Still needs a bit more time to fully carbonate, but it tastes phenomenal. The yeast may have given me some problems, but I think I'm going to give it another go.

 

[domdom]

from what i've read wlp007 is a slightly higher attenuating version of the whitbred/safale 04 strain. wonderful strain but does finish on the higher end (anywhere from 1.014-1.020). i've used both and the wlp007 finishish 2-4 degrees lower. i've heard of folks stirring to get the yeast back into suspension mid-fermentation. seems like the reason the beer clears so quickly w/ this type strain is that it drops out (flocculates) very quickly, hence the lower attenuation.