I have been to a local mill shop yesterday, they had a nice cracked corn but the old dude refused to sell it because it wasn't food grade. I appreciated his honesty. It's hard to find the good stuff this time of the year, he said he was not sure if there were preservatives or not, so I guess YES.
What about using corn meal? I've seen some youtube videos but I'm not convinced. You can't separate the backset with corn meal.
Thanks
PS: I live in a 18th century mill house, there are 2 big stone mills left, one is complete. I'm planning to restore the water wheel in the future so I can crack cereals by myself