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Mjc

Yeast Fermenting Temp Fluxuations

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So I know you don't want wide temperature swings during fermenting.  As my area warms up with the arrival of spring, my ability to control temperature is on a learning curve (it was easy when the house was 68-70 to keep it in the mid 60's.)  I keep my LBK in a large cooler and put in a 1/2 gallon container of water next to it and into the container I put frozen ice bottles, (theory being that the water helps temper large/quick temperature shifts from just putting in a big block of ice.  At the moment I am learning how much each bottle of ice will cool the wort and how long it will last.  I am aiming for 65-67 fermenting temp.

 

Anyway my question is, what plays a bigger factor in off flavors due to temperature swings, the amount of swing or the actual temperatures.  IE is it worse to swing from say 66-72 or from 66 to 60.  My gut says a swing on the low side is better, but wanted a bit more conformation than my gut.  Last night i got up to 70, so before bed I put in a bit extra ice, this morning I was at 63, again trying to stabilize around 65-67,  I am not overly concerned that a one day shift of 7 degrees (while not ideal) is going to ruin my batch, I was curious about the consequences of wide swings like this one, particularly going in the "cold" direction.

 

Thanks for any insights.

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I would be surprised if that swing from 70 last night to 63 this morning was the temp of your wort.

 

There is no reason to put the frozen bottle in water, just put them in the cooler.  1 or 2 should keep things constant.

 

You don't want high temps, and you don't want swings.  Going down to 60 would basically stop fermentation.  

 

I've not done experiments, nor do I suspect have most people, trying to determine which is worse.

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I would be surprised if that swing from 70 last night to 63 this morning was the temp of your wort.

It is more comprehensible than you think. A large coleman ice pack in a 48qt cooler will drop wort temp 5 degrees in just a few hours. If he is using water bottles than it is not too far fetched.

 

As a UPS driver who worked anywhere from 12-14 hours earlier this year do to weather delays I would come home to find my wort in the low to mid 70's and I would replace the coleman ice pack with a large and small pack to slowly bring it back down to 68F then 64F by the time I went to bed. In my experience with this some things did become rather self evident. The first 12hours are most important by pitching quality yeast at the appropriate temperature. Keeping the yeast at around 68F instead of 64F for the first 12 hours is beneficial. After the adaptive phase is completed and the attenuative phase has kicked in the yeast, given that it is a good quality, will hardly be effected by said temperature ranges. I did notice with Mr. Beer Yeast that there was a slight fusil taste in the first couple of bottles but settled out around the 5 week mark. Using Safale US-05 I found no such notes in taste.

 

I think people over react to temperature fluctuation to some degree and most understandably so. However, in my experience if you use a quality yeast, aerate properly and control the temp enough for the first 12-24 hours (longer if you have a high gravity beer) than you should be fine. The adaptive phase is the most important because the yeast are weak and influenced by bacteria and wild yeast. Once things get rolling they are much stronger than some people believe. They are in fact exothermic organisms that would not be around today if they were as brittle as some make them out to be no matter the "theory" behind such a damsel in distress.

 

Now this goes with out saying that just because you can doesn't mean you should. A certain amount of O.C.D will benefit in the over all product and control should be taken seriously. Buying a small refrigerator (about 4 cubic feet) and an STC-1000 controller is a great way to keep things in check. Sort of a fire and forget sort of thing instead of laboriously exchanging ice packs or bottles. If that is not the case then you are going to have to deal with fluctuation. Remember, pitch a quality viable yeast, aerate properly, and control the adaptive phase as much as possible and you will be fine so long as the temp doesn't get too high.

 

To be clear I am not advocating such a liberal control on temperature merely stating that the yeast are not going to file a complaint to HR about the air conditioning. Understand that brewers make wort but the yeast make the beer. What you put in is what you put out and keeping things consistent will yield the best quality product. However, this is also a HOBBY and extenuating circumstances may alter those plans so do your best or get a mini refrigerator.

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I would be surprised if that swing from 70 last night to 63 this morning was the temp of your wort.

 

There is no reason to put the frozen bottle in water, just put them in the cooler.  1 or 2 should keep things constant.

 

You don't want high temps, and you don't want swings.  Going down to 60 would basically stop fermentation.  

 

I've not done experiments, nor do I suspect have most people, trying to determine which is worse.

Would this include the beers that use T-58? My keg is in the basement and the stick-on thermometer reads about 61. For the first week to 10 days it was between 61 and 64, but has dropped with the cooler temperature over the past 4-5 days. Would that yeast go dormant at those temps?

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If you look up T-58 you will see it is designed to work from 53.6 to 77, with ideal temps 59 - 68.  Therefore, no, it won't go dormant at 61.

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Would this include the beers that use T-58? My keg is in the basement and the stick-on thermometer reads about 61. For the first week to 10 days it was between 61 and 64, but has dropped with the cooler temperature over the past 4-5 days. Would that yeast go dormant at those temps?

Nope

 

-edit-

Rick beat me...

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My problem is that when I add a bag of ice to the cooler the temp drops to 55 - 59. When I take it out the temp will rise to the mid 60's or higher. I left the ice out and the lid off for about 5 hours today and the temp was 68. 

I don't have a stick on thermometer. What I'm using is a remote. The kind you would use for meat or BBQ'ing. I have the sending unit leaning against the keg so I'm probably getting air temp more than wort temp. 

The fluctuations are usually from 56 - 66. I put an icepack in last night and this AM it was 57. 

It does seem to be foaming a bit but I don't know how much it should be. 

I would rather have it slow than fast but I don't know if the yeast dies when it gets to cold or just slows down. 

My cooler is a small Styrofoam ice chest. It will hold the keg if I put it in diagonally. I usually put the ice, it's in a baggy and wrapped in a towel, on the lid. If I put it down the temp drops too much.  

It's been about 30 hours now since I put it in the cooler. 

About 40 or so years ago I made some beer and just kept the carboy in the bathtub with cold water surrounding it and that worked well. That's not a option now. It came out great but that was the last time I made beer until yesterday. 

Any help or suggestions would be greatly appreciated....

Thank you...

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Hi John and welcome aboard,

 

I am using the coolers and find that it takes several hours for the wort to collect the cooler temp. When  the ice is melted usually after about 12 hours for my omaha styraphoam the wort equals cooler temp. stays stable for the next 12 hours.

 

6 hours temp test is favorable

 

I use temp probes in the wort but find that a 3-4 degree increase closer to the top of the LBK. Everyones climate is diferent but expect the 3-4 degree increase of temp for a healthy batch.

 

Some folks here use yeast that fits the environment, I do not

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Squeeged Agreed,

 

I rotate 16 oz frozen bottles once a day. In the Evening once the sun goes down the AC is off so Ambients climb.

 

Durring the day in FL @ 96+ the AC is on and ambients are lower or favorable. no Ice required.

 

Cheers

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