Yeast suddenly stops

[Razzmyth]

Hi Guys,

Been brewing my own beer for a few years now. But run into a weird problem lately that I can’t figure out.

The yeast will be very active within 8 hours of pitching but stops suddenly about 24-36 hours later. I leave it sit for a full 5-7 days but it never starts up again.
I’ve lost my last 5 batches due to this problem.
All but 1 were during the winter months (Canada) so I thought maybe the cold was the problem. I do have a fermentation chamber made of rigid pink foam and a heating belt run by a STC-1000 controller. I thought the belt might be getting old and having trouble keeping up so I moved the chamber to my living room. Didn’t fix it. Then I thought maybe the yeast needed a bit of a boost to start, so I tried a yeast starter. Nope didn’t fix it. My last thought was the city water, but that is what I’ve been using for years with no problem. This last batch was definitely at 22-24 degC the whole 36 hours. I shook the carboy vigorously to get lots of oxygen in there. Fresh packet of yeast. It went great for 36 hours and then just stopped.


My brew process.
I brew 1 gallon batches.
Bring 7 liters to boil and boil for 10 min
0.900kg 2 row Pale malt and 0.100kg Crystal Malt in a bag in another pot
Pour in 5 liters at 93 degC
Cover and let sit for 60min
Temp drops to 72 degC
Pour out 4 Liters wort back into boil pot
Pour in 1 liter of 100degC water through grains and into boil pot
Wort, 5 liters, 1.026, temp adjust to 1.041, about 68% efficiency
Add 7 grams Hallertau hops and bring wort to boil
Add 4 grams hops at 50 min
Wort boiled for one hour total
Immersion chill down to 22 deg C in 6 min
Add 5-6 grams of Safale US-05
Shake one gallon carboy vigorously
Place into fermentation chamber at 22 degC

I don’t understand why the yeast is stopping suddenly. I’ve been using the same process for over two years now. I have no idea why the last few batches have just stopped. I even did an extra good job of cleaning and sanitizing this time but nope no difference (I didn’t think it was contamination).
Any ideas would be appreciated.

 

[GilSwillBasementBrews]

After 3-4 days the active part of fermentation is most likely over hence why they seem to "stop". But they will slowly work at consuming other byproducts of fermentation. Even though there appears to be no activity leave them be for a while longer anyway. If you're concerned with the stopping affecting your FG check it with a hydrometer to see if it has stalled or is just done active fermentation. It sounds like your making a problem where there isn't one. I think you're good to go.

 

[LLBeanJ]

What have been the FG's of the brews in question? Are you measuring FG with hydrometer or refractometer?

From your process, are you mashing at 93°C (200°F)? If so, I wouldn't think that would yield much in terms of fermentable sugars. Also, although the damage would already be done, the pour over grain sparge @ 100°C (boiling) is too high. Your sparge temp should be <76°C. A room temp sparge will work just as well.

What is the actual temp (prior to compensation) of the wort when you take your OG reading? According to my calcs, you would have to be around 57°C if 1.026 measured = 1.041 actual (based on 15.5°C (60°F) hydrometer calibration temp). You should be cooling your wort to <38°C (100°F) before taking a reading and then doing the temp correction. The higher the wort temp, the less accurate the corrected reading will be.

Also, depending on the yeast, if brewing a small beer (e.g., 1.041), 24-36 hours may be all that is required to get the job done.

 

[Minky]

I'm not used to thinking in metric, but if I understand your process, you are mashing at a very high temp. Mashing should be done in the range of 64c to 70c, with 67 being a good medium. Pouring 5 liters of 93c water into 1kg of grain gives you a mash-in temp of about 87c. You mash temp is too high to produce a fermentable wort. To mash in at 67c, your strike water should be about 70c. You should also try to insulate your mash tun so you don't have such a loss in mash temp.

EDIT: Just to clarify, my strike water figure of 70c is the stabilized temp of the water already in the mash tun BEFORE the grain is dumped in. It's much easier to hit your mash-in temp that way rather than to try and calculate how hot your water needs to be to pour in over your grain, accounting for heat loss to your tun, etc.

 

[m00ps]

are you dumping these batches before they are even done fermenting?

on average, ales need between 2-3 weeks to finish fermenting (this does NOT mean of airlock activity). As previously said, the yeast continue to work even when they arent gassing off tons of CO2.

Also, your fermentation temps are very high for a yeast like US-05. You should be running them 3-4 degrees C cooler

 

[kombat]

OP, you'll get more feedback if you report in imperial units (gallons, pounds, Fahrenheit), but it sounds like you're mashing too hot (less fermentable wort) and fermenting too hot (stimulating the yeast, causing them to finish early).

 

[Razzmyth]

Sorry, I forgot to post the gravity (hydrometer).
When it goes into the carboy it's typically around 1.050-1.055 at 22degC.
After 2 days when I believe the yeast has stopped it has dropped to 1.030-1.035.
I leave it for another 3-4 days and it is still at 1.030
Same thing for 5 batches now.

Sorry about the metric stuff, canadian eh

 

[Razzmyth]

I store my grain in the freezer. That's why I've been pouring in (mashing?) at about 93C. After the mashing in the temp drops to 78C after about 1 min.

I wasn't 100% sure about the drain(sparge?) temp. I should have read more on the process.

I've made probably a dozen batches with this process with no problem. And good tasting beer.

 

[m00ps]

Your gravity stops at 1.030 because you are mashing waaaaay too high. I dont even mash out as high as you are mashing the full time. This gives your wort too many unfermentables and leads to a cloyingly sweet beer.

You need to be mashing around 66C for good results

 

[Razzmyth]

Yes, I think that's where I went wrong. It makes since.

Thank you, appreciate the advice. I'll try again this weekend but at a more appropriate mash temp. And lower my fermentation temp.

 

[kombat]

Ditto. And dude, you're killing us with the metric crap. And I'm Canadian! Fact is, the brewing world is stuck using imperial units. 78° C doesn't mean anything to me, I had to do a conversion on Google (172° F). Most people aren't going to do that much work to help a stranger on the Internet. Make it easier for us to help you and we will.

 

[flars]

Ditto. And dude, you're killing us with the metric crap. And I'm Canadian! Fact is, the brewing world is stuck using imperial units. 78° C doesn't mean anything to me, I had to do a conversion on Google (172° F). Most people aren't going to do that much work to help a stranger on the Internet. Make it easier for us to help you and we will.

Being an American, with limited mental capacity, I found a way to make conversions faster and easier. A conversion calculator, permanently placed on my desk top. Available for free download. Type "Josh Madison conversion calculator", into Google. Twenty-one different tabs for selecting conversion categories.

Liters at the gas pump still perplexes me though.

 

[kh54s10]

You can do the conversions. Mash between 148 and 154 Fahrenheit depending on the beer style (most styles) and ferment most ales in the mid sixties. Don't pay any attention to bubbles in the airlock. Take gravity readings to determine final gravity.

Your hot temperatures left a lot of unfermentables in the wort, thus the high FG. Fermenting to warm will create off flavors and harsh tasting fusel alcohols. It will also make the yeast chew through what they can ferment very quickly which is not necessarily good.

 

[Razzmyth]

Thanks for all the advice.

I can usually switch between the two systems ok but Fahrenheit confuses the heck out of me. I will convert my C to F for any new posts.

I'm starting a new batch right now, I'll post how it turns out.

 

[Gavin C]

Just one other thing to add

Measuring gravity of samples this hot will lead to very inaccurate measures, even with the correction algorithms. These are useful within a narrow range of the calibration temperature of the hydrometer. Take a sample, cool it under some of that cold Canadian tap water to 60 or 68F (roughly 15-20c), and take your reading. You will have better data to use this way. The calibration temp will be written on the hydrometer

Even with a normal healthy fermentation, it is not uncommon for airlock activity to slow/halt 3-4 days post pitch. With the right conditions, pitch rate and wort quality the yeast do their thing in days not weeks. There is still metabolic activity of course but without the same visual results (bubbling airlock)

 

[Razzmyth]

Quick update.
This batch is turning out much better.

Put boiling water in mash tun and let cool to 167F
Pour in 2lbs 2row pale malt and 0.2lbs Crystal malt
Temp dropped to 154F and one hour later 149F.
Boiled and hopped for one hour.
OG 1.052
5 days later FG 1.012

Can't wait to drink it.
Thanks again

 

[Gavin C]

Quick update.
This batch is turning out much better.

Put boiling water in mash tun and let cool to 167F
Pour in 2lbs 2row pale malt and 0.2lbs Crystal malt
Temp dropped to 154F and one hour later 149F.
Boiled and hopped for one hour.
OG 1.052
5 days later FG 1.012

Can't wait to drink it.
Thanks again

Sounds to me like you hit it out of the park. Solid stuff. Congrats. Thanks for the follow up.

One other thing you can do with small batches with BIAB is to put the mash tun in the oven on a hold warm setting (145-150F). Works well if the pot fits. On the other hand your mash method seems solid so there is a good argument to be made for not changing it.