Fermentation Restarted?

[ncbrewer]

First time this has happened. Belgian Pale Ale in the fermenter 17 days - checked gravity at 1.0085. (I use a narrow range bottling hydrometer, read it to a tenth of a gravity point, and corrected for temperature.) Beer was crystal clear. Then checked at 21 days - should be ready for bottling. Gravity 1.0087 - within accuracy limit. But now the beer is hazy. It tastes good. No airlock activity for many days. The yeast is BE-256 at one packet in 5 gallons of 1.054 SG wort. Active fermentation was at 69F followed by warming up to 76F for the remaining time. I can see three possible explanations:
1) Some of the matter floating on the surface made the sample hazy. But it really didn’t look like much floating - pretty much the same as usual.
2) Fermentation restarted but hasn’t progressed to the point of lowering the gravity. This really doesn’t seem reasonable either. I think gravity would have dropped by the time the beer got hazy. Also, it is already at 83.8% apparent attenuation - it shouldn’t be restarting.
3) An infection is starting. I don’t have much experience with infections, but it seems like this would also lower the gravity?

So to be on the safe side, I postponed bottling and will check again in a few days. But I’m stumped as to why it got hazy but the gravity didn’t drop. Does anybody have any ideas about this?

 

[lumpher]

If ferm is restarting, and it's getting cloudy, it's very likely due to infection. If you keg, I'd keg it, then charge it and chill it asap.

 

[hotbeer]

Might not be infection. Just let it go and see what happens. Might be your yeast is able to work on some of the more complex sugars and it just took them a while to get them broke down enough to go crazy on.

I've had fermentations stop, the beer clear up so I could see to the other side of the trub/yeast at the bottom get started fermenting like crazy too after several weeks and get cloudy again. I just waited them out and bottled when they cleaned up and I could again see to the other side of the trub layer. Bottled and they were great beers. At least for me they were.

 

[GoodTruble]

Yeah, if nothing weird is growing on top, I would just wait it out. Some fermentations stall and restart.

 

[ncbrewer]

Thanks for the ideas. I had planned to wait 5 days after the second gravity check, but I think that could be too soon. If it’s an infection, I would expect gravity changes to be fairly slow. I think bacteria and Brett work much slower than yeast. A check in another 5 days might not show a noticeable change. I’m thinking I’ll wait another two weeks from the second gravity check. Then if gravity hasn’t changed, I’ll bottle. If it’s not an infection, no harm done. (And I should have mentioned first thing that there is no sign of a pellicle.) Thoughts?

 

[ncbrewer]

An update: I waited 15 days after the second gravity check and took another sample. Gravity was stable, and I bottled - waited three weeks and chilled. For pouring, I left the beer out for 20 minutes to warm up a little - that’s my usual procedure. It was overcarbonated - gushed a little and stirred up some sediment from the bottom. For the rest, I didn’t let it warm up. Keeping it cold kept it under control - no foaming in the bottle, although they were still all overcarb’d. I then checked the gravity of a conditioned beer and found that gravity had dropped by 0.003 since bottling. I decided there is an infection.

Well, the overcarb’d batch was made with Williams Brewing LME. And I later found that another container of their LME (this time it was Nut Brown) had fermented in the package - the pouch was totally swelled up. I emailed Williams and they refunded for the bad LME. Then I asked about reordering, since I didn’t want another contamination issue. I got this response:

“I spoke to Bill and we do not know when or if we might get more Nut Brown. We do have quite a bit until we run out. Not all of it has been bagged. We've only had a couple that started to ferment in the bag. The other sizes seem to be fine. We do believe it may have had to do with the hot weather. It is refrigerated here and we are now going to put a sticker on the bags in warm weather to refrigerate on arrival.”

So I feel like my overcarb’d beer might have suffered from the same problem. Probably contaminated LME - and as it turns out, I added some of the extract after flameout and forgot to let it steep for the usual 10 minutes. The combination probably caused the infection. And I don’t believe that putting a sticker on the bags is an appropriate solution to the issue.

 

[BrewnWKopperKat]

@ncbrewer : thanks for sharing some good detective work!

Also cross-posted: https://www.homebrewersassociation.org/forum/index.php?topic=38399.0 and Williams Brewing - Extract Fermenting in the Package

 

[AlexKay]

It's infected ... but how does it taste?

 

[ncbrewer]

It tastes fine, and really no different from the other normal batches.