Broken thermometer --> Too low mash temp...so what?

[tsukemen_king86]

Hi there, relatively new brewer but experienced cook and fermentation enthusiast. I'm doing BIAB and I've got a 35L Klarstein kettle with a built in thermometer, which seems to have kicked the bucket much sooner than it should have. This is something I noticed in my last brew when the thermometer read 95°C (203°F) but wort began boiling anyway, whereas in the past it had only boiled once it got to 100°C (212°F), as it damn well should have. This of course likely meant that my IPA-oriented mash—which I had done at 68°-64°C (154-147°F)—was also going to be off. I took some deep breaths to quell my rage and decided to just proceed with the help of a spare thermometer. Later, after cool down, and aided by the spare thermometer, the kettle thermometer was reading about 10°C (15-20°F) less than actual, and in subsequent tests has shown about the same. Thus, my mash actually happened at anywhere from 54°-62°C (129-146°F), and I suspect it was at the lower end of that because of what I've observed during fermentation. My initial hydrometer reading was 14.1°P when the liquid went into the carboy. I pitched Wyeast California Ale that had become active over 36 hours in a 2L starter. Fermentation has been at a really consistent 18-20°C (64-69F) and began in first 6 hours. It was super vigorous for two days before slowing down—and it slowed down much more abruptly than previous brews. I took a reading at day 3 and got 6.1°P. Also at this time, I racked the liquid off the trub in to a clean carboy.


It's now been 7 days since brew day and my reading was the same as day 3: 6.1°P! This tells me, among other things, that primary fermentation has all but ceased and I can take my current numbers to calculate ABV and attenuation. This gives me an apparent attenuation of a mere 57%, and an ABV of only about 4.5% (when I was aiming to get it around 6.5%). The taste of the beer has some IPA characteristics: really solid bitterness for example, and nice simcoe and cascade notes, though there is a slight lingering sweetness, at this point. I don't detect any off-flavors right now, in fact it's quite pleasant at this particular stage. Though I'm entirely unsure of how it will continue developing.

So, I'm wondering if I can get any sage wisdom from anyone out there. Have you ever accidentally mashed at temps that probably straddle the protease and beta-amalyse phases? Is that low mash temp directly responsible for the low attenuation, or did attenuation stop because I racked into another fermenter too soon? What happened with your beer in a situation where you mashed too low or racked off the trub too soon? Would it be better to drink asap or might it actually get better if I age it for a while? Can I pitch some Brett or lactobacillus and see what happens? Any anecdotes or advice is very welcome!

 

[doug293cz]

If your thermometer reads low, that means the temp is actually higher than you think. So if your thermo reads 10°C low, and it indicated 68°C - 64°C during the mash, you actually mashed at 78°C - 74°C (172°F - 165°F.) At those temps, you would denature the beta almost instantly, and the alpha amylase in just a few minutes.

Brew on

 

[NotSure]

Hi there, relatively new brewer but experienced cook and fermentation enthusiast. I'm doing BIAB and I've got a 35L Klarstein kettle with a built in thermometer, which seems to have kicked the bucket much sooner than it should have. This is something I noticed in my last brew when the thermometer read 95°C (203°F) but wort began boiling anyway, whereas in the past it had only boiled once it got to 100°C (212°F), as it damn well should have. This of course likely meant that my IPA-oriented mash—which I had done at 68°-64°C (154-147°F)—was also going to be off. I took some deep breaths to quell my rage and decided to just proceed with the help of a spare thermometer. Later, after cool down, and aided by the spare thermometer, the kettle thermometer was reading about 10°C (15-20°F) less than actual, and in subsequent tests has shown about the same. Thus, my mash actually happened at anywhere from 54°-62°C (129-146°F), and I suspect it was at the lower end of that because of what I've observed during fermentation. My initial hydrometer reading was 14.1°P when the liquid went into the carboy. I pitched Wyeast California Ale that had become active over 36 hours in a 2L starter. Fermentation has been at a really consistent 18-20°C (64-69F) and began in first 6 hours. It was super vigorous for two days before slowing down—and it slowed down much more abruptly than previous brews. I took a reading at day 3 and got 6.1°P. Also at this time, I racked the liquid off the trub in to a clean carboy.


It's now been 7 days since brew day and my reading was the same as day 3: 6.1°P! This tells me, among other things, that primary fermentation has all but ceased and I can take my current numbers to calculate ABV and attenuation. This gives me an apparent attenuation of a mere 57%, and an ABV of only about 4.5% (when I was aiming to get it around 6.5%). The taste of the beer has some IPA characteristics: really solid bitterness for example, and nice simcoe and cascade notes, though there is a slight lingering sweetness, at this point. I don't detect any off-flavors right now, in fact it's quite pleasant at this particular stage. Though I'm entirely unsure of how it will continue developing.

So, I'm wondering if I can get any sage wisdom from anyone out there. Have you ever accidentally mashed at temps that probably straddle the protease and beta-amalyse phases? Is that low mash temp directly responsible for the low attenuation, or did attenuation stop because I racked into another fermenter too soon? What happened with your beer in a situation where you mashed too low or racked off the trub too soon? Would it be better to drink asap or might it actually get better if I age it for a while? Can I pitch some Brett or lactobacillus and see what happens? Any anecdotes or advice is very welcome!

It sounds like you're thinking too much into this. Your yeast quit it seems to me. First try rousing them and if that doesn't work, then re-pitch. I could be wrong.

 

[Birrofilo]

You are possibly going to have a beer with a lot of "body" given by complex sugars and dextrines. I would make a syrup water-sugar so as to reach your original 6,5% ABV or even something more, in order not to have a too unbalanced beer between body dimension and alcohol dimension.

Or maybe just carry this on as it is. Ultimately it's beer, and it will not give you belly-ache.

It would have been wiser to make a iodine test after mashing to confirm that at least you had no starches in the wort. But starches, as well, are food in any case. Embrace this beer with curiosity and enthusiasm, and don't give it to anybody on a strict diet

I wouldn't store them for too long before drinking because certain yeast strains will slowly consume also the complex sugars that they did not touch in the first round, and considering you might have a lot of complex sugars, you might have a good candidate for a beer-bomb.

 

[IslandLizard]

Can I pitch some Brett or lactobacillus and see what happens?

You'd be better off pitching some glucoamylase. It breaks the dextrins down to fermentable glucose and fructose.
If all works well, you may end up with a gravity a tad below 1.000.

 

[VikeMan]

It sounds like you're thinking too much into this. Your yeast quit it seems to me. First try rousing them and if that doesn't work, then re-pitch. I could be wrong.

As @doug293cz hinted, the very high mash temperature would have caused a very unfermentable wort. If @tsukemen_king86 described the facts accurately, it's pretty unlikely there's a yeast problem here.

 

[NotSure]

As @doug293cz hinted, the very high mash temperature would have caused a very unfermentable wort. If @tsukemen_king86 described the facts accurately, it's pretty unlikely there's a yeast problem here.

I'd like to think you're right, if temps were really that much off, then there'd be a really low efficiency, which I have yet to hear about.

 

[VikeMan]

I'd like to think you're right, if temps were really that much off, then there'd be a really low efficiency, which I have yet to hear about.

Higher temps can actually yield higher mash efficiency. With reasonably good diastatic malts, conversion (i.e. conversion of starches into something other than starches) doesn't take very long. In fact, it happens faster at high temps, as long as the enzymes hold out. It's always a race between enzymatic activity and denaturing. Fermentability is usually the thing that suffers when high temps denature enzymes more quickly.

I've seen OP's story played out many times on the forums. Reasonably good conversion and terrible fermentability is a common theme.

ETA: Here's a good paper on the relationships between mash temps, enzyme activity, extract (i.e. efficiency), and fermentability:
https://onlinelibrary.wiley.com/doi/pdf/10.1002/j.2050-0416.1991.tb01055.x

 

[hout17]

I want to pose a question to you. What elevation are you at? If at sea level then yes 212 degrees fahrenheit should be your boiling point.

I live at an elevation of 4,984 feet so my boiling point is approximately 203 degrees fahrenheit and my thermometers agree (all of them).

I see that this gets overlooked sometimes so I'm throwing it out there.

Brew on!

 

[tsukemen_king86]

If your thermometer reads low, that means the temp is actually higher than you think. So if your thermo reads 10°C low, and it indicated 68°C - 64°C during the mash, you actually mashed at 78°C - 74°C (172°F - 165°F.) At those temps, you would denature the beta almost instantly, and the alpha amylase in just a few minutes.

Brew on

Man, I thank you for letting me down gently for my outrageous oversight. Much appreciated!

 

[tsukemen_king86]

@VikeMan Right on for the research paper. @hout17 thanks for the astute question but no, I'm at sea level.
And indeed, thanks a lot to all for the helpful replies. @doug293cz correctly pointed out my egregious oversight, and while I briefly thought to attempt salvaging the beer with a sugar-water syrup or glucoamalyse, in the end I've decided I'll just go through with what I've done and learn from it. I'm still fairly new to this so I think I can allow myself some room for error. Perhaps it's a good thing to follow through with a known error and see what happens. Besides, I'll get some first-hand knowledge of what a beer tastes like when this happens. ****, might even brew a batch with mash temp too low one day, just to know it through the experience of drinking 19 litres of it.

Now, one more thing to see what y'all think: as I've decided to go ahead as planned, on day 7 I threw in about 60g of hop pellets for my planned dry-hop. About 24 hours later, the liquid has gotten pretty active again and fermenting more vigorously than it has since the krausen went down I just dropped the pellets into the carboy, which I've read can introduce oxygen, so I'm guessing this is why activity started again? I'll check the gravity again tomorrow (day 10) and see if anything's changed.

 

[VikeMan]

Now, one more thing to see what y'all think: as I've decided to go ahead as planned, on day 7 I threw in about 60g of hop pellets for my planned dry-hop. About 24 hours later, the liquid has gotten pretty active again and fermenting more vigorously than it has since the krausen went down I just dropped the pellets into the carboy, which I've read can introduce oxygen, so I'm guessing this is why activity started again? I'll check the gravity again tomorrow (day 10) and see if anything's changed.

If by vigorous you mean there is some airlock bubbling, it could be a bit of "hop creep." Hops contain enzymes that can break down wort/beer dextrins into fermentable sugars.

OTOH, reinvigorated bubbling can also be the result of a pressure change, or even just off gassing from the trub.

 

[Birrofilo]

Deleted, there was an answer by an hour but I did not refresh the page.

 

[tsukemen_king86]

"Hop creep", that's a new term. Well it's not vigorous per se, it's just more vigorous than it's been since the initial attenuative phase. That is, the air lock is pushing through a bubble every 6-7 seconds now, but had only been doing so every ~20 seconds between attenuative phase and when I added the dry hops.

Let's see how it develops. If indeed, as @Birrofilo says, there is a good candidate for a beer bomb, perhaps it would be good to let this rest in the carboy for 3-4 weeks. Might be a bit long for beer to be on hops, but guess I'd rather some possible grassiness than a bottle-bomb.

 

[VikeMan]

Let's see how it develops. If indeed, as @Birrofilo says, there is a good candidate for a beer bomb, perhaps it would be good to let this rest in the carboy for 3-4 weeks. Might be a bit long for beer to be on hops, but guess I'd rather some possible grassiness than a bottle-bomb.

I think you'll find the airlock settling down long before then. When it does, take a gravity reading, and again 2-3 days later. If it's stable, it's done.

 

[tsukemen_king86]

Took a gravity reading just now and it's gone from 6.1°P to 5.1°P. That seems somewhat significant given that the gravity read 6.1 on the third day after yeast pitching, and 6.1 on the 7th day after yeast pitching. As you say, I'll check again in a couple days and see what it's doing.

 

[tsukemen_king86]

Three days later and the brew is now at 4.9°P, so it's still doing it's thing. I'm going to be out of town from next week so I've got to bottle soon. @Birrofilo mentioned the possibility of a bottle bomb, but I'll be bottling into 750ml Belgian bottles equipped with bail-top's (a la Grolsch) so I'm fairly confident I won't have a bomb (though if anyone has contrary experience, I appreciate you saying so!).

Cheers and thanks all for the advice!