Long Term High Temp

[fatmarmot]

Hello,

I am brewing a clone (extract) of Young's Oatmeal Stout and I may have simmered my yeast. I pitched the yeast, from a good starter, at the recommended temp of 70 degrees. The yeast were active and showing vigorous signs of life in the 6 gal plastic bucket within 30 minutes. However, overnight, when the house temp went down to 58 I put an electric fermentation heater around the primary and it stayed there for nearly 20 hours. (At the 10 hour mark, early a.m., it appeared the lid was going to get blown off.) Anyhow, I was told the fermentation heater would only raise the temp 5 to 7 degrees, however, I believe that is false.

When I finally transferred the fermometer from the glass carboy I have (I am currently making hard cider as well) - the temp wouldn't register. I realized this was because it was too warm to show on the scale that tops out at 78 degrees. My beer must have been in the 80s. At the 24 hour mark the yeast activity was still going strong.

I have read that I may get off flavors and that I should give the yeast extra time to clean up the mess in the primary. I should also get another fermometer. (My temp controller is on it's way, but I had to get started.) For the sake of learning though - could anyone please comment on why this leads to off flavors. How does it happen? What kind off off flavors?

Thanks a million. HBT has saved me a lot of worries over my yeasties since starting.

 

[dstranger99]

The yeast work faster at the higher temps, but the faster they work, the more fermentation by-products are created, and they can only reconvert or absorb so much.

 

[WoodlandBrew]

Are you talking about a stick on thermometer? If it was in direct contact with the heater you may have damaged it. Perhaps you can take the temperature with an oven thermometer to verify? Or you could put ice on the thermometer to see if it will register a lower temperature.

I would expect the temperature of a five gallon bucket will drop 15% every hour.
http://woodlandbrew.blogspot.com/2012/09/swamp-cooler.html

Like you said, it may have some off flavors. Only time will tell, and time also cures a multitude of problems.

 

[dcp27]

unless you have a feedback loop, a heater can't know what 5-7F higher than temp is. was it a brew belt? if so it keeps it around a constant 75F so with active fermentation u were definitely in the 80s. house temp of 58F would've been perfect during active fermentation, it would have kept it properly in the low to mid 60s like you'd want. take off the heater and let the temp come down asap. different yeast will kick off diff flavors, but you'll likely be dealing with alot of esters (fruitiness) and probably some fusels (solvent-like). extended time on the yeast cake can reduce these tho

fyi, never pitch at 70F (except maybe in a saison/belgian), always pitch below the desired ferment temp, which is like 62-68F for most ales. and since active fermentation creates heat, you'd want your ambient temp a few degrees below that or use a swamp cooler to better maintain temp