All corn mash, stuck ferment

[Orpheus123]

OK, this is a long story, so I'll try to be brief.

I decided to do an all corn mash for a corn whiskey. Here's my setup:

4 gallons of water
12 lbs flaked corn (so it didn't need to gelatinize)

Heated water to 167 degrees
added Corn
Let sit at 167 for 60 minutes.

Holy gloppy shit mess batman. To make it worse, I forgot to check the PH, and it was way high after this point. SO...

I split the mess into another pot, and added like 2 and a half gallons of water between the 2 pots to make it manageable. I then added citric acid to bring the PH down to 5.6 for both pots. By now, I'm frustrated (I get like that) and I can't say for sure that there is an equal amount of corn in each pot, but it was "close enough". I let it cool to 148 degrees and added amylase. 1 tsp per pot, one pot was at 3 gal and the other at 5. Covered and sat for 90 minutes. Checked it after 30 minutes, no conversion per the starch test, so added another tsp of amylase to each. At 90 minutes, refractometer showed 13 brix or 1.052 on one, 12 brix or 1.048 on the other. I figured good enough, this was already turning into a shit show.

Since it was still thick as hell, decided to ferment on grain, never done that before but there was no separating this stuff. After dumping it into my fermenters it came out to just about 4 gallons for each...

Sigh. So I adjusted PH to 4.5 each, cooled temp to 88 degrees for one, the other was 89.5. Added 2 tsp yeast nutrient per bucket and aerated, then pitched 2tbsp dry DADY yeast. It began fermenting in a couple of hours. But VERY slow.

Then it pretty much stopped a couple days later. I checked gravity, and it was only 1.038 on one, didn't bother checking the other. Both were considerably thinner though, so I guess that's good. There were some bubbles on the top, like suds not fermenting bubbles. I stirred it up and added another TBSP of DADY yesterday. It bubbled out the air lock immediately, but I suspect that was just from stirring it. Checked it this morning, and nothing.

It smells like sour fermentation but there are no bubbles at all and the airlock is sitting like there's no pressure at all. I seems this thing is a dead stick.

Should I add more yeast nutrient? Yeast? Throw up my hands and pitch it?

Thanks!

[Orpheus123]

Also, the temp is 86 degrees, which is ok for DADY I believe. I'm fermenting in the garage, so the temp is pretty stable out there.

[8Ball]

You didn’t convert the starches into fermentable sugars. Get some gluco enzymes and/or malted grains and add at the recommended temperatures.

[Orpheus123]

Huh. I figured since I had gotten a specific gravity result, I got fermentable sugar.

So, basically bring the mash back up to temperature, add some malted grains and basically redo the mashing process again? I didn't even think you could do that!

[shadylane]

I let it cool to 148 degrees and added amylase. 1 tsp per pot, one pot was at 3 gal and the other at 5. Covered and sat for 90 minutes. Checked it after 30 minutes, no conversion per the starch test, so added another tsp of amylase to each.

Since it was still thick as hell, decided to ferment on grain,

Sounds like you used the wrong enzyme.
Most folks around here do a 2-stage process that uses Alpha to convert the starch into dextrin and then use Gluco to convert the dextrin into fermentable sugar.

[shadylane]

Huh. I figured since I had gotten a specific gravity result, I got fermentable sugar.

So, basically bring the mash back up to temperature, add some malted grains and basically redo the mashing process again? I didn't even think you could do that!

You can but it's additional work.
Small batch = small mistake.
Buy some High temp Alpha and Gluco and start over.

[Orpheus123]

Thanks, I'll do that...

...but I'm gonna put myself through the hassle and see if I can save this one. If nothing else, I learned something AND it's better than being at work!

[Orpheus123]

BTW, I used Alpha Amylase...thought it was the same as gluco.

So...cook the corn to high temp, add high temp alpha. Then when it cools down to 150 or so add the gluco?

[Sporacle]

That's the basic process, add the high temp at its recommended temp.
If you can it may be helpful if you're stirring constantly during your heat up to add some high temp at the start to aid with thinning during heat up (I get my AA in one litre bottles)

Unless you have a real problem with your water the pH will generally look after itself, I've found testing th pH constantly just gives me one more thing to worry about

Add the gluco at the gluco temp.
Good luck

[shadylane]

BTW, I used Alpha Amylase...thought it was the same as gluco.

So...cook the corn to high temp, add high temp alpha. Then when it cools down to 150 or so add the gluco?

You only did 1/2 the process and there was very little fermentable sugar.
Therefor it wasn't a "stuck ferment" the fermentation ended early when it ran out of sugar.

Sporacle's advice is good.

[Orpheus123]

OK, so this is what I ended up doing.

I heated both mashes back up to 148 degrees. I added the Alpha amylase (I don't have the gluco yet, so I'm just going with what I have for now) and let it sit for a couple of hours (I had a wedding to go to). When I checked it later, the starch test showed clear, and the SG was 1.048. Considering all I have put this thing through, I'm fine with that.

I'm pitching nutrient and DADY today as it has cooled down overnight. Since the starch test shows clear, I'm assuming I got some fermentable sugars here.

I ordered the High Temp Alpha Amylase and the gluco as well, which I'll use on my next batch. It seems you are to add the gluco at the same time you pitch yeast, which seems odd to me, but that's what the label says.

I'll let y'all know how this batch turns out. Thanks!

[shadylane]

You can add the gluco as soon as it comes in, It will work at fermentation temps and convert dextrins to fermentable sugar at the same time as the sugar is being consumed by the yeast.

[Orpheus123]

Wow...should have checked this post before I emptied the mash! Heh. It didn't budge for 3 days, so I assumed it was dead. I now understand that the Alpha converts to dextrin, the glucose converts the dextrin to sugar. So, even though I had a gravity reading, there was no sugar in it, only dextrin.

Learn something new every day. Gluco is on the way, next batch will be done right. This is the first all corn I've done, and I didn't realize it required 2 stages of enzymes. SO...I'm assuming you would do this with the gluco in a bourbon as well right? Just because there will be unfermentable dextrin from the corn in there...

[shadylane]

Here's how Pintoshine does all corn mash.
Yes, the mixer is annoying.

[Orpheus123]

Thanks for that, it's a real help!

[shadylane]

I now understand that the Alpha converts to dextrin, the glucose converts the dextrin to sugar. So, even though I had a gravity reading, there was no sugar in it, only dextrin.

Dextrin is basically lots of sugar molecules linked end to end.
Gluco chops the dextrin into individual sugar molecules.

I'd recommend SEBstar HTL and SebAmyl GL.

[Orpheus123]

OK, one last query...maybe...heh.

High Temp Alpha would be used if you are gelatinizing corn correct? You would heat it up to like 160, add the amylase, then continue to heat up to like 190.

If I am using flaked corn, it has already been gelatinized. That means that I could heat the corn to like 150, then add regular alpha, and let it sit at that temp for like 90 minutes. THEN, cool it down and add the gluco when I'm ready to pitch yeast.

Just trying to see if there is a quicker way with the flaked corn. I think I was just missing the gluco, that and I probably didn't heat up the flaked corn and let it sit long enough, so my alpha didn't really do the job. But if I HAD maintained the temp at like 145 to 150 for 90 minutes, since it didn't need gelatinization I would have been fine for that conversion to dextrin.

I appreciate your input. Thanks!

[SW_Shiner]

I’ve always found the easiest way with corn, is to bring water to near boiling, or to a boil. Then dump it on top of the corn and wait for the temp to drop naturally to the right temp. This is for cracked corn ground finer through a mill. I have no experience with flaked corn but I can’t imagine it having any negative effects doing it the same way.

[Orpheus123]

Yes, that makes sense, given that I'm fermenting on the grain. Just dump the grain into the fermenter, then dump the water in and stir it up good, then add the alpha amylase. No worries about scorching with this method...and since flaked corn does not need to be at gelatinized, it should do fine sitting in the fermenter without worrying about maintaining temp for an hour. I don't know why I never thought of that! Sheesh...

[Sporacle]

Just be aware that dumping the boiling water onto the flaked corn in the fermentor may lead to a couple of issues.
You can lose temp too quickly due to ambient temp, temp of the corn and insulation of the fermentor. I have experienced this personally and had to reheat the entire mash.
Personally I heat the corn and enough water to keep it liquid along with a splash of AA to help thin as it heats.
When the mixture gets to temp I add the remaining water at the correct temp to reach my AA temp and the whole lot goes into an insulated cooler.
I get much better conversions doing it this way.
This is just my method, heaps of people use the dump method with success

[Orpheus123]

I think I'll get to this tomorrow afternoon. I'll let you know how it goes.

[Orpheus123]

OK, this was...interesting.

I heated the water to 180 degrees, I figured since it's flaked corn, it doesn't need to be so hot. I learned. It needs to be hotter. You were right, I lost temp really quickly even though I had the corn in the fermentor for a few hours to make sure it was at least ambient temp. The advice I got was to heat to 190, or even boiling, then dump the water, mix the corn and add the High Temp Alpha. I did that, just not hot enough. So basically, I added the high temp and let it sit for an hour. It was down to 150 at that point, and starch test revealed tons of starch. So. I learned there. I added regular alpha amylase at that point and let it sit another hour. It cooled to like 135 or so (I have to check my notes) but the starch test revealed that indeed, starch had been converted. I then let it cool to about 120 and added the gluco. The bag I got did not say what temp, but as I understand most here would pitch it with the yeast. I figured, what the hell, see what happens. It sat overnight.

This morning I checked it and it was SUPER sweet. It came in at 15 Brix, and I took a sample and used the hydrometer, and it showed 1.066. Like...wow.

It's cooling a little more then I'll pitch nutrient and yeast. Basically, it worked, I just need to heat that water way hotter to do the pour method. Curious how long it will ferment.

I'll update this thread. Thanks all for your help!

[Bradster68]

I add my gluco at 130. Some add a little higher.

[shadylane]

I then let it cool to about 120 and added the gluco. The bag I got did not say what temp, but as I understand most here would pitch it with the yeast.

I wouldn't say "most" only some folks, because they can get away with it.
Gluco works slower at temps less than the manufacture recommends.
A nice thing about gluco, is fermentation will naturally drop the pH to the range that the enzyme works best at.

[Orpheus123]

Well, it's happily bubbling away right now! I did this one right...

[Pure Old Possum Piss]

I usually add the HTL or alpha on the way up to 190° so I don't wind up with a barrel of Corn-crete. Hold it at 180-185 for an hour. Let temp drop to 155-60 if using malted grains or 150 if using gluco amylase. Hold it there an hour. Starch test it and if everything converted good let it cool to under 100 to pitch yeast the next day. Others do it different, but this has never let me down.

[Orpheus123]

So, it took almost 2 weeks, but it is dry as can be! One fermenter shows less than 1.000 and the other is right at 1.000. So...I guess I did it right. Thanks to all who contributed. I have one more batch to make and now I know how to do it. Cheers!

[Orpheus123]

Repeated the process on another batch, only this time I heated the water to 195 before dumping and added the high temp alpha. Still had starch at 150 degrees, but threw in regular Alpha and let sit. It was starch free when done. I added gluco at 130 degrees. Super sweet the next morning. Fermented dry in less than a week.

The strip run on both batches yielded almost 3 gallons, so pretty good. Spirit run yielded 3525 ML at 140 proof. I am aging 1 liter in a jar with a oak infusion spiral at a level 3 char. I saved a small amount aside for new make to compare when aging is done, and the rest I proofed down to 110 proof and put in a barrel that had aged my last bourbon. There it shall sit and we'll see.

All told, I'm really happy. You guys taught me something about enzymes, and this is by far the most I've ever produced from an all grain. Thanks again. Next up, might be a heavily peated single malt.

Salud!

[greggn]

You guys taught me something about enzymes

Next up, might be a heavily peated single malt.

If you're going to do all-barley you may want to add a beta-glucanase enzyme to your tool kit. Unless you ferment on-grain, then you're cool.