I'll add that he needs to learn NOW that food aggression is not acceptable. Going for your hand when you take his food? No way. A guttural UH-UH (mama dog grunt) along with, if needed, scruffing his neck (mama dog discipline). Don't lose your temper, don't make a big deal or yell. Simple, firm, no-doubt-about-it, impersonal & effective discipline. If you reach for the food you get the food. He must never drive you away by aggression from anything you want to do.
The way to teach a food-guarder to stop guarding is to teach the dog that you'll never forcibly take his food away- build trust- so he has no reason to guard it. You teach him that it's GOOD if you handle his food because you not only always give it back, but you usually give him extra goodies as a bonus.
There's a little booklet called Mine! you can buy that goes carefully over the tried- and proven- protocol for fixing resource guarding.