First time brewer - hot fermentation question

[Cannae216]

Hello all,

I am brand new to brewing and the forum, so apologies in advance as I am sure this is a question frequently asked...

I did my first brew on the weekend, started with the training wheels and did the Brewer's Best Weissbier kit. The brew went fine, however My OG was quite high (1.061 vs. target of 1.050) even after diluting with some water.

In order to account for the high OG, I decided to ferment at the higher end of the recommended temperature for the yeast (Danstar Munich). I placed the carboy in my temperature controlled freezer, set to 72F and walked away. Within 24 hours I had what I would consider signs of a very aggressive fermentation, and was happy I had used a blowoff tube.

Within 48 hours, the bottom of my cooler was coated in what it believe is water from my blowoff bucket, and the fermentation shows no signs of slowing.

My concern is that my high temperature ferment is going to overwork the yeast and create off-flavours. Although I tend to prefer weissbiers with a banana flavour, I don't want this to be overkill.

After poking around this, and other, forums, I also see that internal carboy temperatures can be 5-10F higher than surface readings on a carboy. I would expect I am on the higher end of this range die to the aggressive ferment.

On to the question(s)....

1) was it a good idea to do a higher temperature ferment to account for higher OG? I didn't really have a reason for this other than it felt right...

2) Should I crank my temperature down to low 60s to attempt and salvage what I can, or is the damage already done at 2 days at high 70s? Will the sudden drop in temperature cause an issue?

3) Is it safe to take a sample with a beer thief during an aggressive ferment, or should I wait a few days? I would love to know what the internal temp is when my setup is set to 72F

Overall, I would appreciate any answers to the above and perhaps some expert opinion on whether I can expect 5 gallons of juicy fruit flavoured swill, or if my first ever home brew might yet be salvageable...

Thanks in advance!

 

[blizz81]

1) was it a good idea to do a higher temperature ferment to account for higher OG? I didn't really have a reason for this other than it felt right...

Yeah, this one doesn't really make any sense to me. If anything, you'll possibly maximize the attenuation of the yeast, getting more alcohol.

2) Should I crank my temperature down to low 60s to attempt and salvage what I can, or is the damage already done at 2 days at high 70s? Will the sudden drop in temperature cause an issue?

You can try lowering it now, but yes, the proverbial "damage" has pretty much been done by this point. It's probably not too bad, probably just going to be fairly banana-ey.

3) Is it safe to take a sample with a beer thief during an aggressive ferment, or should I wait a few days? I would love to know what the internal temp is when my setup is set to 72F

Sure - at the point of aggressive fermentation, CO2 is outgassing / pushing out, so you're at low risk of oxidation or bacteria / wild yeast exposure. Just make sure you sanitize what's stuck in there I suppose. Can take a temp reading directly in the vessel, and this would be good for you to see how much temp difference there can be between ambient and inside the vessel mid-aggressive ferm. I had an S-04 ferm get away from me where I had my chest freezer set at 66* (probe just dangling on the inside), and it probably hit the low 80s before I realized (by the time I measured, it was at 79).

 

[Dumpsterboy]

Don't stress it or overthink it at this point. It'll probably be just fine. In the future I would just stick to the recommended fermentation temp, and not worry about an OG that was slightly higher. Enjoy it!!

 

[Cannae216]

Thanks for the fast reply. To confirm, I did set my fermentation temp within, albeit at the maximum of, the fermentation temperatures. What I failed to adjust for was the difference between internal and external carboy temperatures. The fact that this delta can be 5-10F is really what causes me "worry" (as much as I can worry about a hobby I suppose)

I will try and take an internal temperature reading tonight and see how far out of the range I landed.

Thanks again, I'm sure I will post again soon...

 

[blizz81]

Thanks for the fast reply. To confirm, I did set my fermentation temp within, albeit at the maximum of, the fermentation temperatures. What I failed to adjust for was the difference between internal and external carboy temperatures. The fact that this delta can be 5-10F is really what causes me "worry" (as much as I can worry about a hobby I suppose)

I will try and take an internal temperature reading tonight and see how far out of the range I landed.

Thanks again, I'm sure I will post again soon...

One thing you'll see over time by means of brewing different styles and just reading about different yeast strains is you'll gain a general understanding as to the behaviors of different yeasts. Hefeweizen yeast strains are often very aggressive and generate a lot of thermal heat in the quick-peaking fermentation. So starting out on the upper-end can be difficult. Though you do have a fermentation chamber / freezer it sounds like, so you've got a good start!


I had done a good number of brews in my freezer and never had much of an issue dialing in a ferm temp with the probe dangling free inside the freezer (would generally set 4-8 degrees lower than desired ferm temp depending on yeast aggression), but the experience of the S-04 blowing up on me led to rigging up insulation on the probe and securing it to the vessel w/a bungie cord. The lessons we learn as we go.

 

[RmikeVT]

Just as an FYI -- the optimal yeast temps are the "optimal yeast temps". There isn't a direct relationship between OG and optimal ferm temp. That is to say, as you increase gravity the optimal temp for the yeast does not increase.

Fortunately, you used a Weiss yeast which are some what tolerant to higher temperatures and will tend to throw off banana and bubble gum as they get hot.

Some folks do ramp up ferm temps toward the end up fermentation as a measure to help the yeast condition, but don't usually go much higher than 70ish and it is at the tail end of active fermentation.

 

[Cannae216]

Thanks. I will definitely keep this in mind for future batches. Living in a colder climate (ambient basement temp is about 60F) I was quite worried with keeping the fermentor at the "right" temperature. In hindsight, I likely would have been better off leaving the carboy untouched in the basement. Ah well, such is life.

I was hoping for something on the higher end of banana/estery, so here is hoping.

Eventually I would like to try a Belgian Tripel brew, so if this works out I suppose I'll just say I was getting ready for future batches...

Thanks again for your input folks, seems like a great community.

 

[Cannae216]

As an update...

Fermentation has died down quiet a bit, replaced blowoff with stamdard airlock with star san Took a sample and am siting at~73F, which is only slightly above the max temp range. Although, I am sure during the vigorous fermentation it was likely higher.

I have knocked the temp setting down to 69, plan to go to 67 tomorrow and then leave it alone.

Gravity was already down to 1.028 from OG of 1.061, I think this is pretty fast for only 48 hours in the primary...

I smelled the sample, didn't notice any nail polish remover or overly banana notes, which is good. Tasted a small bit and didn't notice anything alarming.

Overall, cautiously optimistic on this one! Happy to hear any thoughts on this, including whether the plan to slowly lower temp. makes sense.

 

[aprichman]

If you're able to temp control something like a fridge you are going to want to set the ambient temperature ~5F below your intended fermentation temperature.

For example, if you are shooting for ~68F in your carboy set your ambient temperature settings to ~63F. As fermentation dies down you would slowly raise the temperature.

Keep in mind that when beer ferments you are creating ethanol, CO2, and energy in the form of heat!

Cheers

 

[RM-MN]

0) If you use extract, the only way to overshoot your OG is to undershoot the amount of water. Extract has a set amount of sugars.

1) It is almost always better to start the ferment at the cool end of the yeast's preferred temperature to control the rate of the ferment, then allow it to come up as the ferment slows to help the yeast finish up. Starting too warm leads to the production of fusel alcohol which gets you a hot alcohol flavor and leads to a hangover if you drink too much.

2) You don't want to reduce the temperature as the ferment slow down as the yeast may quit working and go dormant.

3)Taking a sample during the active ferment won't really tell you much other than if the ferment is happening. Krausen and activity in the fermenter will tell you that. Instead you want to wait until the activity ceases and then take a reading to verify that you are near the expected final gravity. Another sample in a couple days that remains the same will verify that the ferment is complete and you can bottle or you might still wait a few more days/weeks for more yeast to settle out so you get less sediment in the bottles.