Fermentation Temperature Question

[Blazeburns]

I'm pretty new to home brewing but have been doing lots of reading. One thing I haven't seen covered is the effect of fermentation temperature on the flavor of the beer. Is there a rule of thumb?

I ask this because I brewed my first batch of Bavarian Hefeweissen from an extract kit (Northern Brewer) and it came out great with lots of banana flavor and very similar to authentic samples from that region. That was fermented at around 63 degrees. I did a second batch to test the effect of brewing at 71 degrees. Much less banana, less authentic, more like an American wheat beer. That ought to answer my question, but I don't trust that I held every other variable constant (ie I didn't do a secondary for the second batch and added half the malt extract with 15 minutes left).

Here's the biggie - I've read information that says you get the banana from lower fermentation temps, while other, also seemingly, reputable sources say you should brew on the higher end for more banana flavors. Does anyone really know? I guess my experience says lower, but I don't trust that one simple test.

Plus, I'd like to know if there is an overall rule of thumb that dictates what types of flavors are favored at lower and higher fermentation temps.

 

[blackbear219]

I've got a Hefe (my first one) that's been in primary for about 48 hours now. The first 24 hours it smelled like regular wheat, but the last 24 hours it has smelled heavily of banana. It is at about 68-70. My basement is absolutely perfect for the high-60s this time of year, it seems. Definitely seems like the ~70 is gonna give me plenty of banana.

 

[Thehopguy]

I'm pretty new to home brewing but have been doing lots of reading. One thing I haven't seen covered is the effect of fermentation temperature on the flavor of the beer.

Seems you've been reading the wrong things

 

[Thehopguy]

You should ferment in the temperature range specified for the yeast your using. But I believe the higher temps are giving you the banana smell.

 

[strat_thru_marshall]

I'm pretty new to home brewing but have been doing lots of reading. One thing I haven't seen covered is the effect of fermentation temperature on the flavor of the beer. Is there a rule of thumb?

rule of thumb? sure, ferment ales between 62 and 70F (wort temp, not ambient air temp) and ferment lagers between 48 and 55F.

Will temperature effect flavor profile? You bet it will. Each strain will react differently though. Theres no general guideline like "62F = banana, 64F = Clove" If you keep it within those guideline temps you will typically avoid nasty off flavors, but can still experiment with ester and phenol flavor and aroma production. Typically cooler fermentation = cleaner fermentation while warmer fermentation= more esters and phenolics....though is is not always the case. Again, it's largely strain dependent.

 

[RugenBrau]

Get your hands on the book Yeast :A practical Guide to Beer Fermentation by Chris White and Jamil Zainasheff. It can get pretty deeep and way over my head in parts but there is plenty of info in there that the homebrewer can use. The more I brew the more I understand it. Great info on temp and temp control in the fermation section. It was one thing that I always ignored and you don't have to spend a ton of $ to fix it. A swamp cooler works fine

 

[Blazeburns]

rule of thumb? sure, ferment ales between 62 and 70F (wort temp, not ambient air temp) and ferment lagers between 48 and 55F.

Will temperature effect flavor profile? You bet it will. Each strain will react differently though. Theres no general guideline like "62F = banana, 64F = Clove" If you keep it within those guideline temps you will typically avoid nasty off flavors, but can still experiment with ester and phenol flavor and aroma production. Typically cooler fermentation = cleaner fermentation while warmer fermentation= more esters and phenolics....though is is not always the case. Again, it's largely strain dependent.

Thanks to everyone for the replies and info. This forum is awesome and I hope to be able to help others out down the road. It sounds like the answer to my question is like a lot of answers in life - "it depends." That's part of what makes brewing so much fun.

In my two hefe attempts, I was within the recommended temp range both times - just different parts of the range. I was trying to figure out how much the difference in flavor was attributable to that and how much might be other things. One thing I didn't consider was the wort temp vs. the air temp as strat thru marshall mentioned. Does anyone know generally how much temperature difference there is between wort and air at the height of fermentation? Half a degree, two degrees, five degrees? Just a general ballpark would be nice to know if anyone can put it there.

 

[strat_thru_marshall]

Does anyone know generally how much temperature difference there is between wort and air at the height of fermentation? Half a degree, two degrees, five degrees? Just a general ballpark would be nice to know if anyone can put it there.

Depends on the ferment, but I have read that it can be as much as a 10 degree difference between the center of the actively fermenting wort in a carboy or bucket versus the ambient air temperature of the room. Fermentation is an exothermic reaction, it generates heat as a byproduct. The amount of heat that is generated will be directly linked to the speed and intensity of your fermentation, which is related to the health of your yeast, your pitching rate, and the gravity and fermentability of your wort.

I typically strap the temperature probe of my controller to the side of the carboy with tape, and then insulate it with a few folded up towels and a piece of styrofoam taped over it. This insulates the probe from the air and gives a pretty accurate indication of wort temperature, without messing with thermowells or sticking the probe in the beer itself.