Fermenting too warm

[i-a-n]

Hopefully this isn't too naive a question, and I can't find much detail on it, but..... What is the likely outcome of fermentation at too high a temperature?

 

[manticle]

Fast fermentation, higher levels of esters and fusels mainly.
It depends very much on the particular strain of yeast and what constitutes a higher temperature.
Wort composition, pH etc will play a smaller role as well.

 

[spryzie]

It'll still be drinkable.

My 10% Export Stout using S04 went up to 26 degrees - was done well inside 48 hours!

I taste quite a lot of raisin flavour- not a horrible thing.

Though I preferred my first effort where I kept it to 20 degrees.

 

[i-a-n]

I've often had a ferment be nice and warm, it's always been drinkable, but I'm wondering if I've blamed some of the less desirable flavours on other factors.

 

[antiphile]

That Manticle and spryzie are on to something there. This one backs up their expertise with, what I personally, find a simpler explanation by Ashton Lewis from Brew Magazine:

High fermentation temperature alone won't ruin a beer.
Temperature does playa crucial role in flavors
generated from yeast during fermentation. As temperature
increases, fermentation rate accelerates; with this faster
fermentation come more aromatic compounds. The aromas
arise because the metabolic rate is going along at such a clip
that more metabolic intermediates are excreted from
the yeast cell. I liken this to people getting stinky and sweaty
during vigorous exercise.
Fruity is the most common type of aroma associated
with warmer fermentations. This generic term includes
aromas reminiscent of banana, pineapple, and pear, which
belong to a class of compounds called esters. Some esters,
like ethyl acetate, smell like solvent (ethyl acetate is used in
acetone-free fingernail polish remover). I don't mind fruity
beers, but I hate smelling fingernail polish remover when
trylng to enJoy a plnt.
Warm fermentation also increases the concentration of
higher alcohols. Higher alcohols, a class of compounds, are
known for their spicy, vinous aroma and the propensity to
cause headaches. Strong beers normally have detectable lev­els
of higher alcohols, but normal gravity beers, like the one
you brewed, shouldn't have a detectable level.
If you discover after bottling and aging that your beer
smells fruity, solventy, and vinous, the warmer fermenta­tion is probably the culprit.

 

[Bribie G]

Some yeasts such as Wyeast Ringwood can be "pushed" to 22 degrees to introduce interesting esters.

Wyeast Irish Ale can handle 24-25 degrees perfectly as that's how they brew Guinness with a 40 hour primary fermentation and their yeast (a close cousin of Wyeast Irish) is selected for that task.

Blanket statements about fermentation temperatures are often contradicted. For example many commercial lagers are done at 13 degrees or above, that would horrify the old-school 10 degree brewers.

 

[Mardoo]

Bribe G can you say what Ringwood throws when pushed? Just about to start messing with Ringwood.

 

[Bribie G]

Sort of fruity in the way that Coopers commercial beers are fruity but more stonefruit than pear or banana. Ringwood can be slowish to start, when krausen first appears I take the gladwrap off and give it a big thrashing with a slotted spoon to put more oxygen into it.

 

[Not For Horses]

Get a bottle of Morrison Brewery Red Ale if you can find it. That will be a great indicator of ringwood at low 20s.

 

[Not For Horses]

Back on topic though, the fusels and higher alcohols often associated with higher than recommended ferment temps can be real headache juice.
Following the temp guide from the yeast manufacturers is a good start. If they recommend 22 as a top, do that. If it's 15 for the top then do that. It's definitely not one size fits all.

 

[leighaus]

i had an ipa that was a bit warm.. Had a mild bananarama go to it (could smell it gurgling out the fermenter)... It mellowed out mostly in the bottle and was still a delicious drop. dont be too disheartened.

 

[mr_wibble]

i had an ipa that was a bit warm.. Had a mild bananarama go to it (could smell it gurgling out the fermenter)... It mellowed out mostly in the bottle and was still a delicious drop. dont be too disheartened.

Would that be the 80's bananarama in jeans and big hair or the later model bananarama all dressed in black, and perhaps a bit more subtle & stylish.

Maybe my palette is a bit sensitive to higher alcohols, but I think I can really notice warmer fermentation.

Since I got my fermentation fridge, my beers have been significantly better. It also means I can still make beer in (The Cruel) summer when ambient temps are ~28C all through the house.

Of course it also depends on the beer - you can get away with more in a beer that has a lot going on in terms of flavour (e.g.: a robust porter), as opposed to a lightly flavoured pale ale. If I had 2 ferments, but only one ferm-fridge, the paler beer would be in the fridge every time.

 

[manticle]

What's the shopping basket for?

 

[gap]

What's the shopping basket for?

Maybe to put your bananaramas into.

 

[ricardo]

Results depend on style as well, a Saison for instance works very well at higher temps

 

[Dunkelbrau]

Some yeasts such as Wyeast Ringwood can be "pushed" to 22 degrees to introduce interesting esters.

Wyeast Irish Ale can handle 24-25 degrees perfectly as that's how they brew Guinness with a 40 hour primary fermentation and their yeast (a close cousin of Wyeast Irish) is selected for that task.

Blanket statements about fermentation temperatures are often contradicted. For example many commercial lagers are done at 13 degrees or above, that would horrify the old-school 10 degree brewers.

Those higher ferment temps are also under pressure, reducing ester formation. So the "blanket statements" are correct.. I prefer to call them general guidelines, not rules.

I like to ferment some beers at 18, 20, 22, and even go as low as 14 for some ale yeasts.

 

[ManVsBeer]

I can't believe I used to think they were hot. Maybe I was young, dumb and full of I know a bloke who has fermented his Coopers kits at 30c on a heat pad for more than years. He will drink nothing else and you can't have a brewing conversation with him. I haven't tried one but believe his love stems from all the flavours created fermenting like this. Who am I to judge? Courses for horses.

 

[beermeupscotty]

Is there any way to tone-back the compounds (i.e. balance out with others) created from higher temperature fermentation?

By unfortunate circumstances, I recently found my second AG brew - an amber ale - rose from 16C (pitch) to 34C over 34 hours. OG went from 1052 to 1014 in that time. I let it cool down and put the STC at 18C and I believe it has continued to ferment a little bit afterward (unless the bubbles were going backward due to contraction from cooling).

 

[Forever Wort]

How does it taste? You might have to turn it into a "Specialty Beer" with some late additives.

 

[beermeupscotty]

The tastings I've had have been quite yeasty but beyond that, in terms of off-flavours, I'd say there's more fruitiness and perhaps most noticeable is the alcoholic flavour (ABV = 5.4%, so I guess it's higher alcohols?).

However, surprisingly it's actually not too bad, overall. Almost 'regular'. The darker malt flavours come through nicely. I was planning to do a dry hopping of Amarillo, similar to what I tasted of G&G's Mosey on Brown (20g for 5 days). I like the idea of 'Specialty Beer' ;-)

While probably not ideal, I don't think it's a lost batch by any means. My hope is that a lot of the fermentation was done before it got too warm.