Funny smelling mash

[Cefalu]

I'm a newbie at distilling, but have been making wine for 8 years now, so I'm not new to fermenting.

I just made my first mash. It's 65% corn, 10% rye, 13% wheat and 12% 6 row malted barley. My yeast was a wine yeast, ICV D254, and I used fermaid K and go ferm.

It's been fermenting for two weeks now. The gurgling has slowed down to almost nothing, so I am thinking it's time. But when I stir it each day I do get some bubbles from the bottom.

Here's the issue, it smells like sweet vomit, and has a specific gravity of 1.02. But it smelled like vomit from the get go. When I showed it to my 4 year old nephew 12 hours after I pitched the yeast, he proclaimed "oh it smells like my vomit!" And it did.

It's a cloudy yellowish color. Am I on track to put it in the still?

[NZChris]

Stop stirring it. Put a lid on it, airlock if you can, and let it settle. The vomit smell should go away in time, don't run it till it does.

Gravity will go below 1.000

Check the pH

[woodshed]

Were the rye and wheat also malted? If not no way for complete conversion. Everything went through a mill first? Not familiar with your yeast or other additives but is the yeast compatible with such a mash? Some more info would be great.

In my experience it smells like vomit cause the yeast are throwing up in your mash. Often a lack of proper nutrients. That's a heavy corn bill and may need some help. Maybe wrong yeast. Try a pre natal vitamin crushed in your ferment next time around. Or use a yeast for chewing up corn
instead of grapes. Really is a big difference.

[Cefalu]

My pH is 3.6, Interesting, that's red wine wine territory.

The grains were put through a mill first, and I ran them through a blender as well to mill them a little finer.

All the grains besides the corn came from a beer supply place, so they were malted:

Rahr 6-Row Malt
Briess Rye Malt
Great Western White Wheat Malt

Of the yeasts I have used over the years, D254 is my favorite, for wine of course. It's been reliable and I have never had a stuck fermentation. Yeast consumes sugar, assuming the sugar in a grape is the same as the sugar in corn and grains it should work. It's: S. cerevisiae • cerevisiae.

[rad14701]

pH is getting dangerously low so you should consider raising it a bit to avoid stressing the yeast colony...

You should never need to stir your wash/mash once airlocked... At least not unless you are adding something, which you shouldn't need to do unless adjusting pH like you should now...

[HDNB]

i had a similar mash recently. the sweet puke never went away, carried over to distillate and did not age out over 4-6 weeks. dumped it.
mine was jimbo's all malt recipe. i didn't get it hot enough, and gave it an overnite rest.
as suggested by Jimbo and heavily researched thereafter, the culprit appeared to be a bug that produced butyric acid.

[MitchyBourbon]

Butyric acid will react with alcohols in the presence of concentrated sulfuric acid, to form esters. Concentrated sulfuric acid is a catalyst for this reaction. Butyric acid has a boiling point is 163 °C so I wouldn't think much would carry over in distillation. But if enough is present in your boiler it is possible that enough could carry over to the extent that it become noticeable. The best way to eliminate it if it is present is in fact to give your fermentation a rest of a couple days at fermentation temps. This will allow the yeast to reabsorb it.

[Cefalu]

Not that wine and whiskey making are the same but, they both go through a similar fermentation process up front.

But, noted, I won't stir it in the future. In winemaking you have punch it down twice a day, force of habit.

The D254 yeast I used tolerates up to 16% alcohol and pH's down to around 3.2. so I don't believe I wasn't stressing the yeast. The wine I make normally has a pH of 3.4 and alcohol of 14%. It ferments vigorously right to the end, I have never had a stuck fermentation. The grapes here in N. CA have a sugar content of 25-26%, so the alcohol is pretty high.

But, I wonder why my batch became so acidic. Some sort of reaction occurred. I know the yeast drill, I am super clean, and sterilize everything with star and PBW. I am wondering how it got infected.

Anyway, I ran it last night. 10 gallons of wash produced 2 liters of 40% , which seemed a little low. The puky smell improved over time, but was still a little sweetish puky when I ran it. Not horrible though.

It seems OK. But i need to run it again