I have been reading through yeast by Chris white and I was reading about Fusel alcohols which is an area I have Limited knowledge in. Almost all my beers have a “hot” alcohol taste, even the low gravity ones. I’ve always attributed this to me using extract and assumed it would go away when I jumped to allgrain(almost there). In the book he mentioned hot fermentation temperatures can make some hot alcohol flavors and I ferment at 66(coldest room in my house) would this be the culprit of my hot alcohol flavors?
Yes, excessive higher alcohols can be caused by warm fermentation. What matters is the temperature of the fermenting beer and not the ambient temperature. At 66 F ambient, an active fermentation can easily raise the beer temperature into the low 70s. Coupled with a strain that is prone to producing lots of higher alcohols you’ll end up with this hot alcohol tatste.
The good thing is that it will age out.
For your future beers I suggest placing them at least in a tub of water. The larger thermal mass will limit the rise in temperature.
It’s only the temperature during active fermentation that matters for fusel and ester production. Towards the end of the fermentation the yeast doesn’t grow anymore and doesn’t consume amino acids. As a result the pathways that lead to esters and fusels are not active anymore.
Kai
+1
A swamp cooler as Kai suggested will help control the fermentation temp. Another viable menthod is to use a refrigerator or freezer coupled with a temperature controller which works well but will cost more. The idea is to keep the fermentation temperature steady and to the desired level. Fermentation temperature control is imperative to producing the best beer possible.
Kai is correct that age will help. I had an imperial stout that got into the mid 80’s for a day. After 10 days it was at FG but tasted like kerosene. And yes I have tasted kerosene siphoning it from barrels. I left the beer in primary 2 more weeks at a much lower temp(around 60-62F)and the beer tasted great.
Temp control is the one thing I changed that made a true, unqualified improvement in my beer.
I have dabbled with the swamp cooler technique once and day 2 i put the carboy in the cooler and the yeast shocked and fermentation stalled around 1040. Is there a good trick to prevent that or will that issue not occur if the carboy reaches the same temp of the cooler water prefermentation or prekrausen?
What yeast were you using and how cold did it get? I put my fermenters in a tub of water (with ice packs if the ambient temps warrant) as soon as I pitch the yeast and I’ve never had it drop the yeast.
Well it was my first cider and I heard they leave more apple character fermented cold which is why it wasn’t initially put in the cooler. Around 52-54 but that is not including fermentation heat
Did you use staggered nutrient additions? Stress of any kind (too hot, too little nutrients, too much nutrients, too low pH) can all cause yeast to throw off-flavors.
I did use nutrients that batch, I attributed the stall to the drastic temp change. I didn’t adjust ph at all. That batch is fine and being drank ATM anyways, I actually ended up having to repitch yeast but it ended up great.
An excess of FAN will cause fusel alcohols—low molecular-weight proteins are also foam-negative. Might be something to look into if you’re seeing low head and hot alcohol.
Good info…thanks.
Are you sure that it is 66F where you are fermenting? Is the fermenter in a closet? Anyway, the tub heatsink is great way but if the air is truly 66F then pointing a fan at the fermenter while it is on the floor might just do the trick.
To me 66 degrees sounds like an ideal situation for brewing ales. White obviously means fermenting above 70 and most certainly above 75.
And… Are you getting headaches? Fusel alcohols always crack my skull.
No headaches, but yes according to the temperature strip on my carboy