Esters in my ale

I recently brewed a cream ale partial mash from midwest. It came with safale us-05 yeast. I really do like it and it has a hint of hops not to hoppy like a ipa. As I am drinking it out of a glass I noticed a slight fruity smell. After a bit of research it seems to be ethyl butyrate. Its not really too bad but I bet the beer would be better without it. Do I need to ferment at a lower temp? I have a cooler and have it at 69 degrees for ales.

That is a bit high, but do you have the cooler temp at 69 or was the beer temp 69? I believe that yeast does best under 70 degrees. I use white labs and keep my ales at 68 degrees.

S05 gets fruity above 70F. There’s a lot of heat given off in the early stages of fermentation, so you were probably fermenting in the high 70's. You should probably start at 62 and let it come up slowly as the fermentation slows, finishing at 70.

Esters are mostly produced at higher fermentation temperatures. This particular yeast has a range of 59-75 degrees, with a low ester profile. Therefore, I would recommend turning your cooler down to about 66-67 degrees since yeast tend to warm up the fermentor slightly during primary fermentation. Hopefully, this will keep you in the 68 degree range inside the fermenter and lower the presence of ester profiles.

Is it a hop fruity smell, like citrus/pineapple/grapefruit? What hops were used and what was the fermentation temp?

RainyDay said:

Is it a hop fruity smell, like citrus/pineapple/grapefruit? What hops were used and what was the fermentation temp?

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Whoops, just saw that it was 69 degrees, which shouldnt cause off flavors. Im guessing you're reading too much into it and actually have a beer with goos hop flavor! Unless its green apple, then its another issue.

A couple other things you can do to reduce esters are increase the yeast pitching rate, and increase the oxygenation level with pure oxygen.

Ice bath it...Don't do 70's or you'll get a big league chew bubble gum flavor. Also be sure to research your water and make fine adjustments to accentuate the hops.

Yeast behavior is aerobic so it will bounce around and raise the temperatures. Don't be so sure your temp strip is accurate. 05 is really best at 58-60

I'd agree with old world, especially since you want a cream ale to be clean. Have the ambient temperature in the cooler more like 60-65 and you should get a much cleaner fermentation. Also, I would put a thermometer in a glass of water in the cooler to double check, I know my Johnson Controller is about 4 degrees off, so setting it at 69 would get about 73 ambient which could have been at least 75 inside your carboy.

I don't know if I'd keep S-05 super low to be clean, I tried to make a cream ale with it and fermenting it around 60-62 I got a very prominent peach ester. It is a tasty peachy blonde, but not really a good cream ale.

Horseballs said:

I don't know if I'd keep S-05 super low to be clean, I tried to make a cream ale with it and fermenting it around 60-62 I got a very prominent peach ester. It is a tasty peachy blonde, but not really a good cream ale.

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I was just going to say the same thing! S05 is weirdly peachy at under 64 degrees, and weirdly peachy at above 72 degrees, so it has a very narrow temperature range. At 66-68, it's great. Otherwise, not so much.

For under 64 degrees, nottingham works well for dry yeast or even S04. For liquid yeast, Denny's favorite 50 and pacman work very well to 60 degrees.

Great info! Haven't used S05 before, but defnitely don't want peach notes in a cream, sounds like 65 or so ambient is best.

SteelString_Will said:

Great info! Haven't used S05 before, but defnitely don't want peach notes in a cream, sounds like 65 or so ambient is best.

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No, probaby not 65F ambient, as then you could be looking at much higher fermentation temperature. I'd say at 66-68F beer temperature you'd be good.

Good ideas. I will put my probe into water and lower the temp. The peach taste is right on the mark.