Is "unfermentable" wort a thing?

sbaclimber

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I know I am supposed to rdwhahb and I have the hahb part down, but I am really having trouble with the rdw part.
Short version is, fermentation hasn't started...
Long version is, my (electric) thermometer decided to go crazy while prepping my strike h2o and mashing in. The temp. kept jumping around, regardless of how much I stirred. In the end all I can assume was the temp. ended up somewhere between 60C and 70C (target was 66C).
When the boil was over and the wort had cooled I ended up hitting my OG bang-on, but I was still really worried about conversion, so I even did an iodine test (first time in many many years...).
So, everthing was looking good and I pitched 2 satchets of W24/70 (in 26L@14P).
Fast forward 48 hours at 10C and absolutely nothing has happened, airlock dead. :-(
As it is a (for me) new brand of yeast, I figured it might be a dud, so I primed another satchet, seemed to be alive, so dumped that in too...
24 hours later, still no activity.

So, my question....is it possible to hit your OG and pass an iodine test, but still have unfermentable wort!?

Unfortunately I won't be able to check what happens for the next 5 days, and at this point just hoping to return to bubbling when I get back home....but more expecting to return to a dumper. :-(
 
You’re wort is likely fine. Dry yeast, 34/70 is good example, is sometimes is slow start. Liquid yeast is all ready to go, but dry yeast needs to rehydrate and begin metabolizing. Look for any sign of krausen, if you see any white foam on top, your set. The airlock could be leaking as stated above, but when the wort is that cold, it traps a lot of co2. That makes the lag time look longer.
 
I think we'd all be a bit nervous with a lag that long especially with 3 packets in o_O.
Probably a good thing your leaving the fermentor for 5days or you'd fret over it like an expectant parent:D!

Here is a pretty cool exbeeriment that the brew dudes did on ph and extraction in wort it explores sort of what your thinking about with unfermentable wort.
I think it'll put your mind at ease knowing you didn't subject your mash I'm sure to these extremes. Enjoy.
 
but when the wort is that cold, it traps a lot of co2. That makes the lag time look longer.
I never even considered this! That would most certainly explain why about the only time I had a "quick" start was with wort that wasn't yet completely cooled to fermentation temp.
 
Here is a pretty cool exbeeriment that the brew dudes did on ph and extraction in wort it explores sort of what your thinking about with unfermentable wort.
I think it'll put your mind at ease knowing you didn't subject your mash I'm sure to these extremes. Enjoy.
Cool vid! Definitely some interesting info in there...
 
Your mash temp is fine. The original pitch was fine if you're talking about a 20 liter batch. If you didn't us O2 or didn't slosh like crazy to aerate that can be problematic. Pitching at 10C in oxygen-starved wort will lead to a very long lag and very slow fermentation. I'd suggest taking a gravity sample to see if you've made any progress and raising the temp so you won't get a stuck fermentation.
 
With fresh packs of 34/70 I wouldn't worry about O2 at all, they come pre-prepped more or less.

I wouldn't worry to much, when you get back take a sample and see what it's at. 70C is high and you might have made your wort unfermentable, but I doubt it and I wouldn't stress to hard. Literally nothing you can do about it right now so just let it buck and check it when you get home.

If it's a dumper, well it's a dumper Bud.
 
practically necroposting....but an update!
It fermented out and I hit my projected attenuation (75%) / FG dead-on!! :cool:

Of course brew #2 of pretty much the exact same recipe saw my immersion heater die mid-heat of my sparge water, and I ended up sparging ~10°C colder than normal. Took a couple points off my brew-house-efficiency... :(
 
Take a hydrometer reading, could be a leaky airlock bung.


I get this question all the time at work and my first response is always, "Did you take a reading?"

If your lid/bung/airlock wasn't sealed correctly, you can have complete fermentation without every "seeing" fermentation.

The other thing is if you pitched dry directly and it has only been 24 hours, they could just be slow to start. Remember, they have to re-hydrate and come back to life. I never worry until day three and I never panic until day 5.

I'd grab one more pack of yeast and some Energizer. If nutrient is a daily vitamin, energizer is steroids and helps kick stalled fermentations into gear.
 
My fermonsters don't seal nicely to begin with so I operate on the assumption the gas is leaking around the seals.
 
positive note to my brew #2....I dumped in the scavenged yeast from #1 this morning, and 12 hrs later at <10°C it is bubbling away!
Guess it is just a really slow starter from the dried state.
 

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