Starch Conversion

[Oak Pollen]

Ok I am not sure where to start so I will do it at the beginning;
My recipe, 14.5 lb. cracked corn
2 lb. Rye (malted)
1.5 lb. 6 row Barley (malted)
I soaked the corn in 2 gal. of soft water (my well water is extremely high in magnesium) for 2 days.
Then boiled 4 Gal. of RO water with salts added. At the point of starting to boil I shutdown the fire and added the corn along with 1/2 tsp. of amylase.
Then brought the temp back up to 185 f. I had gleization of the corn inside of an hour. At that point the corn would hold a spoon vertical in the middle of the pot
. I dropped the temp down to 151f and added the malt with another 1/2 tsp of amylase. It started to liquify almost immediately. I then held the temp. between 147 and 151 for 1 hour. I checked my conversion and it was as black as the ace of spades. A cooled sample had a PH of 4.6 and the refractometer measured 1.058.
What in the world am I doing wrong? This is my third run and I have yet to get good conversion. I have brewed for a long time, mashing is not new to me but this much corn is. I have read till my eyes bleed and am still at a loss, any help would be much appreciated.

[Twisted Brick]

Corn (especially cracked) needs to be cooked at ~190-200F for 1.5-3hrs to gel properly. Grinding your corn to meal consistency will increase mash efficiency and shorten conversion time.

Your mash was quite thick at 3lbs/gallon. Recommended beginner range for grist:water ratio is 2-2.5lbs/gallon. I mash @2-2.25/gal and typically achieve 1.060-1.068. If you mash in 9gal of water next time, properly insulated, the mash should hold 180-190F for the required time.

RO water is missing many trace elements needed for proper conversion and fermentation. Why not go with your well water?

Your DP (with enzymes) was sufficient for complete conversion, but it appears you were shy on the total conversion time necessary. Let your mash go longer (even overnight) until your iodine test proves good. Also invest in another thermometer. If you mistakenly added your malts at 155F instead of 151F, the enzymes could have been denatured quickly. I have read of a distillery that won't add malts to its bourbon any higher than 145F.

It is possible (however unlikely) that your liquid enzymes were less than optimal (old). It is also possible (however very unlikely) that your malt's enzymes were less than optimal. Remember, the DP of malts varies by batch and is not an actual measurement of enzymes present, but a potential of enzymes. This is why it is advised to include slightly over the recommended DP for a mash. If you're not familiar with DP, do an HD search on Enzyme Calculations or Calculating Diastatic power.

[shadylane]

I have brewed for a long time.... mashing is not new to me but this much corn is.

Cook the hell out of the corn. Mash longer and with more malt
I've had bad luck with no name powdered enzymes that are added at 150'F, get some liquid Gluco and High Temp Alpha.

[Oak Pollen]

Thanks to all! I will heed the advice and try again.

[shadylane]

Just a thought
At first. Don't worry too much about getting it perfect
Perfect is what you strive for, not what you get
Just getter done

[still_stirrin]

I have brewed for a long time.... mashing is not new to me but this much corn is.

Cook the hell out of the corn. Mash longer and with more malt
I've had bad luck with no name powdered enzymes that are added at 150'F, get some liquid Gluco and High Temp Alpha.

I gotta’ agree with Shady’s advice here too.

Dry enzymes have not been very effective for me either. Liquid enzymes, on the other hand, work quickly, especially the high temperature enzymes.

And with that much corn, I let it saccharify overnight (6+ hours). Corn is slow converting unless malted. Also, a fine grind will help conversion by exposing more of the starches to the enzymes.

As an all grain brewer, you know your processes. It’s the ingredients that “trip you up”. Corn can be very challenging, both in the mash tun AND in the lauter tun. Keep after it...you’ll get it.
ss