Banana"ish" smell

[trthskr4]

Alright, I got an UJSM type question here. First the fixins,

7 lbs. cracked corn
2 lbs. 2-row malted
5 lbs. sugar
3 Tbsp. Fleishmann's baker's yeast
5 Gals. filtered water

I backed off the sugar because on the first run I noticed the 2-row had converted almost half of the corn, much more than standard UJSM, and I figured I over sugared my yeast.

When I charged the still this time I put the entire last run back in and ran with fresh wash. Tails were all the way down to 30%. I also added 3 gallons of filtered water to the still because the last run almost wouldn't siphon out of the still it was so thick even at 140* or so.

Problem is when I run it I get a slight odor and the best I can put my finger on is a bananaish sort of sweet smell. It goes throughout the entire run, but it's worse on the heads and the worst on the tails. Middlins are not so pronounced. I found via site search one reference partaining to it as ethyl acetate. The taste of the hearts are ok straight out of the still and get better with a day or so of air. But it keeps a bit of the odor. Any ideas as to what I'm getting? Is this normal or even sub-normal (new word, just made it up. Got a patent on it already)? Thanks for any help in advance.

[Uncle Jesse]

I've had it before in mashes with oats in particular.

[Tater]

You doing on grain ferment and stilling ?You do a grain mash and added sugar right?

[trthskr4]

Uncooked grain mash, sugar added to the backset from previous run then aerated with paint mixer and drill, ferment on the grain then I rack it into a 5 gallon glass carboy and let settle for a day or 2 then rack out of the carboy leaving the trub in the bottom of the carboy.

[Loki440]

Well definitely sounds like your forming a ester compound, amyl acetate or isopentyl acetate perhaps, which is easily possible in our application, but there boiling points are in the 140c range (fusel oils), but other than that if i remember correctly (been awhile) your gonna have to be running quite an acidic environment to get those compounds, which go figure is happening.

but really you should be fine, you might be able to drop out the smell if you reduce the aciditidy of the mash a bit.

But then again my limited chemistry days are in the past so its a little foggy at the moment

[BW Redneck]

Does this smell disappear in the distillate after it's been aired out a few days? If so, I wouldn't worry about it. I've had marmite, play-doh, and bread-like smells come across in raw spirit, but they disappeared after a week or two.

[trthskr4]

You know, come to think of it I didn't have this problem until I insulated my column on my "hybrid" pot still. The decrease in reflux now may be the reason these off odors are coming through. I just collected the first run and topped it because I already planned on putting it back in with the second run. The first batch I did with the 2-row was started with backset from a 5th generation UJSM plain with corn and sugar and I always use 1.5 Gals. of backset in each 5 gallons of wash. This run I'm letting it air out for a few days and see what I get. For the next run I'm gonna remove the insulation from the 18" column and try that unless someone comes up with a better plan of attack. Thanks to all for your input so far, it does take a weight off my mind and give me an idea of what to do.

Imagine that, insulating the column giving you more flavors and smells. Who'd a thunk it?

[Old_Blue]

Sometimes a high fermentation temp will give those odors.

[trthskr4]

Sometimes a high fermentation temp will give those odors.

That's good to know, what is considered high? This fermenter hasn't been above 80*F external temp. I have no heater or anything on it, ambient temp around it has been between 65-80 degrees. It has been violently hitting the airlock (3 piece) at times blowing the water out of it. The fermenter itself has always been cool to the touch.

[muckanic]

Sounds like a variety of esters to me, if it's in both the heads and tails. Many esters taste fruity at low concentrations, and more solventy at higher concentrations. Amyl hexanoate could be the culprit in the tails. Ester formation is enzyme-catalysed by the yeast, and isn't necessarily an acidity phenomenon. Recycling the yeast trub for too many generations could be a factor, as saturated lipids from the yeast are involved.

[trthskr4]

Sounds like a variety of esters to me, if it's in both the heads and tails. Many esters taste fruity at low concentrations, and more solventy at higher concentrations. Amyl hexanoate could be the culprit in the tails. Ester formation is enzyme-catalysed by the yeast, and isn't necessarily an acidity phenomenon. Recycling the yeast trub for too many generations could be a factor, as saturated lipids from the yeast are involved.

That would carry over from the backset? I would have guessed that any enzymatic activity would have been stopped with the act of boiling the wash. Anybody else have any of this with say 8 or 9 generations of a sour mash? Could it be accelerated or caused entirely with the addition of malted barley? I wouldn't think so, but I'm no chemist either. Going to try to set up an experiment of sorts to test this and make a smaller fresh mash without any backset and run it. Thanks Muckanic.

[muckanic]

You can get lipid build-up whether the yeast is boiled or not. Obviously, if you rack off the deposit before each run like you said, then you wouldn't get much build-up, unless you are recycling the unboiled yeast culture.

[trthskr4]

Ahah, That I do Muckanic. After racking off the cleared mash into the still I do add water to the settlement in the carboy and put it back into the fermenter. I throw away most of the slop in the bottom of the still as I am usually afraid that since I use propane to heat the still that it may impart a cooked or burned smell to the next batch.

[trthskr4]

Does this smell disappear in the distillate after it's been aired out a few days? If so, I wouldn't worry about it. I've had marmite, play-doh, and bread-like smells come across in raw spirit, but they disappeared after a week or two.

Yeah, it does. Just went back after letting it air for a few days and the smell is not there. Flavor is great, got oak barrels coming in probably towards the end of next week. Gonna cure them and charge em up. Got 5L barrels at medium char with stands. Racked off another batch from the fermenter today and got a taste of the wash, it's got that flavor to it also. Must just be something in the mix. I'm satisfied with the flavor for now. Thanks everybody, this has been enlightening to say the least (butt puckering at times as I thought I'd have to toss it).

[Husker]

People underestimate the "power" of the angels. A little air can make such a tremendous difference, while only losing a small percentage of the ethanol. It is like running the still. You can make very conservative cuts, lose a little ethanol, but have fine quality. Or you can distilll a very WIDE body, and have more ethanol, but the quality is trash. Same with airing. Give a tiny portion to the angels, and they will bless you with much better quality.

H.

[trthskr4]

Amen Bro. Husker, preacher said something similar to that this morning. Right on.

[trthskr4]

I don't read the fruit section much on the home site but went through it tonight and found this.

Jack adds ...
the majority of flavor compounds in whiskey come from the yeast that is used. The aldehydes that the yeast contributes turn into esters on long aging. These halp to provide a better flavor for the whisky.

This is the first wash I have done with the Fleishmann's yeast. That could explain the different odor. Any body else think so?

[Usge]

Using WD whiskey yeast with AG, I get the "banana" smell in my wash (and my mashes too). But, it doesn't seem to come over so much when I run it. My "monster mash" smelled very much like sweet bananas and grain when it fermented. But upon stripping, smelled like buttermilk/corn and oatmeal.

[Mr.Moonshine]

Yeah, I got that banana-ish smell from my rum wash a few weeks back, came out really really strong smelling in the foreshots, but eased up a bit in the hearts. I let it sit for a bit though, and then redistilled and it came out OK. It oaked out nice

[trthskr4]

I've found it in several different types of washes and also that with airing a little it goes away. But I've had those where it stayed also and had to redistill.