It is wonderful you are starting with training to insure Griffin is comfortable with you and your around high value items. A couple of things stood out in your post and I think some minor tweaks will result in pretty major changes for the better.
Timing is quite crucial in teaching and it's so easy to get things out of order (timing is one of the first things I consider when I hit a snag with my dogs). If you have been putting Griffin's food down and then starting to pat or brush him, you've been teaching him his food (YAY!) = handling (for most dogs this isn't exactly a YAY! moment without training) . Now if you switch up the order and instead practice brushing (it could be picking up the brush and touching his coat for two seconds) and then offer his food it looks like this, handling = food (YAY!). You want either the behavior (at his age, probably not biting the brush is a good start) or the item (the brush) to predict one of the big YAY! moments. You'll know when Griffin has made the connection when he sees a brush and starts getting all wiggly happy puppy because he knows it means great things are coming his way. You can increase the behavior you ask for (being still for brushing for 10 seconds, just as an example) with time; Griffin will let you know if you've asked for more than he's prepared to deliver.
Right now Griffin is telling you he is stressed when you're near his food. This usually doesn't start out with a growl and I'd wager if you watch him it may start with his ears moving back, his eyes changing into a harder expression, strategically placing himself between you and his food dish, freezing in the middle of chewing or eating, then eating faster and more intensely (almost punching the food), and then a growl. If the growl is ignored things can escalate with a snarl, a snap, and then a bite. When you told him no and took his food dish away you confirmed his concerns were quite valid. Don't practice this! Instead begin with the sit and wait, place his food bowl down and with you in a distance *he* is comfortable with toss him treats that are higher value (bonus points if you can land them in his bowl). When he starts to anticipate your approach by doing the wiggly happy puppy behavior you can decrease your distance (I'd "ping pong" the distance and if he's okay at 2 feet, move back to 3 feet, then 2 feet, etc. don't always make it harder for him). Once you have conditioned a great response when you are next to him I'd move on to Jean Donaldson's Food bowl bonuses: "While the dog is eating, approach and add a bonus consisting of something more palatable than what is in his bowl. The addition can be just dumped in or the bowl can be removed, the bonus added and the bowl returned to the dog. The ideal is to alternate. Again, all family members should participate." If at any time Griffin tells you things are moving too fast, give him space. This will be a fantastic opportunity to improve your observation skills and at the same time let Griffin know by him simply putting his ears backs (if that's the initial stress signal), you'll listen to him and there is no need for him to escalate his behavior any further before you'll hear what he's telling you. Suzanne Clothier covers this quite well in a clip from one of her seminars when she discusses counter conditioning and safety at:
http://www.youtube.com/watch?v=KwnSdvHI8mg
There is so much to teach a puppy, it is incredibly easy to focus on the training exercises and not see the puppy. I've been guilty of this and it's a lesson I'll likely need to remind myself of with future puppies. A big difference I see with food bowl exercises are more experienced trainers are likely to keep it as a one trial exercise and not practice it as frequently. With only the best of intentions, some less experienced trainers will attempt multiple trials in one meal time, loom over the puppy while they are eating and inadvertently set the puppy up for failure. It is a very important exercise, but dogs need a chance to eat their meals in peace more often than not.
Definitely discuss this with your puppy class instructor, they will be able to offer better advice by having the benefit of seeing the behavior and able to discuss options with you and your family.
Treat recipes:
Tuna brownies -
http://www.courteouscanine.com/blog/91-tuna-brownies.html
Turkey meatloaf -
http://www.kathysdao.com/recipes.html
Information on why not to punish a growl:
Pat Miller - The Gift of Growl
http://www.peaceablepaws.com/articl...82173843&archive=&start_from=&ucat=1&type=Pat
Pat Miller - Understanding Dog Growling and Dog Language
http://www.whole-dog-journal.com/issues/12_10/features/Training-For-Growling-Behavior_16163-1.html
Joan Orr - Growling at the Kids
http://www.doggonesafe.com/growling_at_the_kids
Laurie Luck - My Dog Growled! Now What?
http://smartdog.typepad.com/smart_dog/2010/02/my-dog-growled-now-what.html
