when the corn is cracked, the ENTIRE kernal is simply rolled-over with a mill stone or run thru a crusher-- NOTHING is "lost"...
It breaks open the mostly undigestible shell so the nutritious inside is available to digestion... (Sorry-- I mis-spoke on the name of it tho!)
Remember- the outer shell is bran-- and THICK bran at that--
Sorry to be gross- but haven't you ever noticed whole, undigested corn in poo? That is because the corn is sealed against digestion by the "bran"...
keep something in mind... ANYONE can write a book... I have gotten a hold of books on everything from raising puppies to gardening that had from "less than reputable" information to some that was downright harmful (like using systemic insecticides on tomatoes, and smacking puppies as a part of training!)
NEVER take the info from a single source as Gospel-- read several books by different authors, look for credentials, and ask people who have actually been doing what you are interested in for a long time-- they are better sources than ANY one book!