zstar5000

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Hi everyone.
I’ve read the threads, consulted the Google, and even prayed about it, but I’ve got a serious issue that I think needs some real expert advice.

I recently cracked open a second bottle of my third and latest batch, and there is a disturbing trend the cause of which I cannot for the life of me figure out. To varying degrees, each batch of beer has had the same sour banana sort of smell during fermentation and taste after bottling. The second bottle of this third batch wasn't as sour as the first bottle, but it was more just plain gross. This taste diminishes slightly after a few months in the bottle, but it’s remains strong enough to detract from the taste of hops in my IPA and the malty goodness in my amber.

I’m all about practicing patience when it comes to letting the yeast finish its job, but I thought more time in the bottle would allow a decent beer time to get better, not be necessary in all my batches to make wretched tasting beer drinkable.

Below I will post the steps and/or ingredients which all three batches have had in common. Hopefully someone will notice a red flag.

1. I sanitize with a 12.5 ppm iodine solution. I’ve been told this is no rinse, and everything I spray with the solution still has some residual spray when I add the wort/beer.

2. I brew partial mash. After steeping I sparge with around 2 liters of water that’s about 80-85 C.

3. Although I do a late addition DME, I probably don’t portion out my bittering hops properly, so each batch is probably more bitter than I would like. This probably doesn’t produce the sour taste, but it certainly doesn’t help.

4. Do to the depressing lack of hop selection here in Korea, I’ve used Hallertau hops in each batch: for flavor in the first, and bittering in the second and third.

5. Carahell grains have been used in all three batches.

6. I keep a thermometer on top of my fermentation bucket. The ambient temp in my apartment is always around 23C, and I’ve never seen the thermometer above 25 during fermentation.

That’s all I can think of right now. If something isn’t on the list I’ve effectively eliminated it as a cause because I’ve used a different ingredient/method on at least one of the three batches.

Thanks for any help!

scrambledegg81

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Your procedure looks fine. First thing that popped to mind is your water quality. Are you able to get a water report from the local government in SK? Also, do you pre-treat (boil & cool) your water before mixing with the wort or do you just dump as it is?

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zstar5000

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I know the water from the tap is not great. I've only been using it for rinsing, however. I've been purchasing and using 5L jugs of water for everything else.

eppo

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Looks like you are fermenting really hot. I like to keep the fermenting temp of my wort at 70F. 25C is 77F and the fermenting yeast release heat as they ferment. I wouldn't doubt it gets to 85F inside the fermenter.

zstar5000

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Thanks for the replies. While I've not seen the temp get over 25C on the outside of the fermenter, I would say that the average temp is very close to 23C (73.4F), which if this is accurate, should be in the safe zone for the yeast. That said, my second batch, which probably averaged closer to 21C, had less of the sour smell/taste, but it was still there.

While Occam's Razor would suggest that since high temps lead to the sort of byproducts I'm experiencing, then I must be fermenting at too high a temp. Do most people ferment in temps around 18C/65F?

justflow1983

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The actual fermentation temperature inside your beer will be 5C hotter than the outside temperature. You need to find a way to cool it down, I ferment my ales at 15C normally which is a bit cool but results in crisp beers.

MattHollingsworth

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The banana sounds like iso amyl acetate, an ester that goes up as the temp goes up. What yeast are you using?

I think you should avoid letting your fermentation get over 19 C. Which means the room should be even cooler. People have all sorts of tricks for keeping it cooler, which you can find with a search. Either that or brew beers that are okay fermenting warmer like some Belgians....

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Weezknight

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The first thing I noticed, as some PP's did, was the mention of "banana" and a fermentation temperature in the mid to low 70's(F). I agree that if you get the temps down to around 18C to 19C you will see those off flavors disappear.

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mitch171

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Couldn't yeast pitch rate and health effect this also. I agree with the heat issue, but I would also try a different yeast, make a starter, and/or use yeast nutrient.

smizak

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Yepper, that temp is definitely a red flag.

I had an oatmeal stout I didn't watch close enough go up to 72F from an ambient room of 63F. Now because of stupid S-04 yeast I have a grossly overly estery varnish stout.

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