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Jun 08, 2022 View:

Corn mash-types and issues

I have just started experimenting with 100% corn mashes. The reason for 100% is to learn its nuances and flavor profiles without any influence from malt.

i started with a chopped corn because that's what the store had and it's cheap. I could grind it but thought working with flour would be a pain. Here are the issues:

1) inconsistent: every cereal mash has been different so far. Taking between 90 min and 3+ hours for gelatinization (holding between 175-200 degrees F). Checking with iodine, goes from clear to starchy (opposite of normal). Once gelled, cooling to 165, adding alpha 2 times at 30 min interval.

2) low yield: 20lbs of corn and 7 gallon resulted in 1.012. Needing to add sugar to get reasonable ABV

What type of corn to commercial distilleries use?

If I grind to a flour, is a cereal mash still required?

Should I go with flaked instead?

What else am I doing wrong? I really want to progress to bourbons, but corn will still be an issue.

thanks for the help.


Alpha alone won't do it, you'll need to use a saccharification enzyme - beta or glucoamylase.  The GA is easier to find.

On the alpha, use a high temp variation.  Add a small dose on the heat up, and then on the cool down - you can add it at a higher temp than 165f.

20 pounds corn to 7 gallons is pretty thick for a first timer, try cutting back to 15 or so until you get the hang of it.

You will get inconsistent gel times unless your grind is consistent, and it probably isn't.  The difference between gelatinizing at 175 and 200 is significant in my book.

I'll pretend you didn't say add sugar to a grain mash.

Also, you didn't mention pH - it's going to be critical on an all corn mash.




Any recommended doses for the gluco and beta? What temp should they be added? 

I didn't want to add the sugar, lol, but had to after measuring the low gravity. 

Thanks for the tips.


You don't need both.  Get the dosage from the manufacturer, it'll be different.


What type of corn are big distilleries using for bourbon? Does gringing the corn help with saccharifi action?


Generally it's commodity field corn.

Everthing else equal, smaller grind will provide faster gelatinization and higher yields, but that has nothing to do with the  problem you posted.




First thing to consider when looking at lower than expected yields is the moisture and protein content of your substrate. Unless your moisture content is very high, 20lbs is a lot for 7G. I agree with the other posters that alpha alone is not sufficient. Alpha is a endoamylase. You also need an exoamylase like beta-amylase. For a rough guide to adding enzymes, I would use something like the below:

Enzymes:Amount per lb (ml)         When?SEBstar HTL0.45        At mash inSEBAmyl GL0.41        Once temp is at or below 140 F

Thoughts in no special order

Almost all corn used in bourbon is #2 dent -- plain ole field corn.  You'll want your corn ground to flour. It's just so much easier to work worth. But don't think you'll ever try to lauter.We use enzymes from Specialty Enzymes. I believe the dose is 36mg / lb of starch.  We assume density of 1gm/ml.You'll need to keep pH within a reasonable range. The HTA we use is between 5.6 and 6.5We get a negative starch test in less than an hourSince we have a small cooker, we mash THICK -- 4 lbs / gallons (we also agitate the shit out of it while cooking)

Once you've made all of those sweet tasting but utterly useless dextrines drop the temp below the denaturing point of the glucoamylase (for use that's under 160) and add it. Dont forget to check pH -- our gAm works between 2.8 - 5.5 (we've never had to adjust).  

Don't try to be a hero like I originally did and go the "natural" route and eschew the use of added enzymes. It's not with the soul that will leave your body or the people you'll offend by cussing whilst dealing with that thick, goopey mess.  And honestly, I find absolutely no organoleptic difference between corn + enzymes and corn + malted barley. Corn isnt exactly subtle.

I'm certain I've missed out something.


Reply:51 minutes ago, SpiritedConsultant said:

I imagine testing the moisture and protein content would be beneficial long term. How do you test those and what equipment is needed? Any recommended sites?


So how does this look for next test batch:

Add 15 lbs chopped corn to 8 gal H2O. I can't handle flour now, but realize that would be preferable.

Add high temp enzyme like Sebstar HTL. Heat to 190F.

Hold until 60-90 min and until iodine tests react well to starch. Should be pretty thick and gummy, correct?

Cool to 160 (probably adding cold water for this). Add Sebamyl GL or other Beta. Hold until iodine tests show sugar conversion.

Should the temp be held steady? What is an average timeframe?

Cool to 70F and add yeast starter. Going to lauter and sparge here until I can distill grain in with flour.

what did I miss? What corn/water ratios are you all working with?

thanks for the help!

Reply:7 hours ago, indyspirits said:
Reply:6 hours ago, BigRed said:

Lower temp for GA - Maximum glucoamylase activity is 55c/130f, and deactivates around 70c/158f.  If you aren't fermenting on the grain, you can add at a higher temperature than 55c as you aren't so concerned about further enzymatic activity during fermentation.

Depending on your gelatinization temperature, you may find you are denaturing a significant amount of HTAA by holding at that temperature.  If so, two additions might be more effective, a smaller amount during heatup to keep the mash thin, and a second larger dose once you've achieved gelatinization and begin to cool.

You also need to consider pH ranges for optimum enzyme activity.




Similar issues with low SG when doing a bourbon mash. I've been doing 60% corn, 30% rye and 10% malt recipe and the results are as follows:

Using flaked corn I hit 20 brix, no added enzymes. Fresh corn I hit 24 brix, again no added enzymes. Dried corn ground to nearly flour and cooked at 190 for 2 hours, then let rest, insulated overnight, results were struggling to hit 15 brix with added amalyse.

I have access to basically unlimited dried sweet corn and want to use it but have tried everything except the addition of tons of enzymes. The fresh version of the same corn off the cob is 24 brix...take it from a silo after a year and I can't get close to 15...any thoughts?

At this stage the amount of effort to get the dried corn to do what we need may not be worth doing a bourbon, but with the amazing corn we have access to, it'd be a shame. My thought was that the super dried out corn loses something else other than water and is causing us the issue we are having.