Corn/grain to malt ratio for mashing ?

[tombombadil]

I've read the 30 dp rule on here and in other places and wondered about it.

Im not a chemist or a biologist (I know there are a few on here so hopefully one of them will chime in)but I do remember high school chemistry class.

My understanding is that enzymes do their work on their substrate and the go looking for another substrate to work on. They aren't 'spent', unless they're denatured by heat or ph.

If that's correct then there's no real minimum requirement for converting all of the available starches to sugar. Having less enzymes doesn't mean that we won't get full conversion, only that it will take longer.

Also, if you're not bringing the mash to a boil then the enzymes aren't denatured a don't stop working so having an average of less than 30 dp is fine because you really only need enough enzymes to get complete conversion in 3 days at 80-90 degrees.

[tombombadil]

All that being said, I follow the 30 dp rule and the 2#/gallon rule when working with corn because the people on here with decades of experience reccomend it.

15# finely ground corn (86%)
2.5# distillers malt (14%)
7.5 gallons water

So, 2.5x250/17.5 = 35-36 average dp

I also toss in about a tablespoon of liquid gluco enzyme so the wash will ferment out totally dry.