J. Stanton wrote an excellent piece on hydrolyzed vegetable proteins and why they are so prevalent in processed food.
Summary of article:
When you extract the oils from corn, soy, etc, you are left with mostly vegetable protein. Hydrolysis (i.e., basically chemical digestion on an industrial scale) is then used to break down the proteins into amino acids such as glutamic acid, known as glutamate in its anionic form. Free glutamate is the molecule that plugs into the taste receptor we call “umami”.
*"Hydrolyzed vegetable protein" is a flavor enhancer…
*…because it stimulates our umami taste receptors, just like soy sauce, Parmesan cheese, or MSG.
*However, it’s much cheaper than real food, because the USA heavily subsidizes the production of corn, soy, and wheat…
*…and, in the case of soy and corn, it’s made from a byproduct of soy and corn oil manufacturing that would otherwise be fed to cattle."