You should not be touching him while he's eating.
I understand you have kids but the dog needs to eat in peace.
Watch the vid. to see how you work with this - the dog should ENJOY you coming near - BUT don't push that! You are still making him feel threatened while he eats.
Food Aggression Rehabilitation - YouTube
Do this until you can approach the bowl without him freaking out. BUT don't touch him. There is no need to. All you need to do is be able to walk by him safely.
Instruct your children to leave him alone while he eats, and keep an eye on them so they don't mess with him.
that dog was made crazy by the trainer, its like if someone pokes me in the chest, I will say "Stop that", then he does it again harder, I say "Seriously, stop that!" Pretty soon, he would be on the back end of my fist.
My point is that you dont need to push a dog to threshold to fix that behaviour.
This may or may not work because, when I did it, my dog was not bad, and was still very young.
When I first switched Maya to Raw food, she was very protective of it (higher value than kibble), The behaviour was mild at first, so I ignored it, then she started growling and barring her teeth, so I said "NO!" I reached in and took the chicken from her, she wasnt happy, she growled and bit my hand (she was only a small pup at the time, so nothing major), I then waited a few minutes for her to calm, and then gave the chicken back to her, she has never growled since, I could tickle her while she eats if i wanted to and she would be fine with it.
As I say, this may not work with all dogs, but it gets the message across that if they guard their food, it WILL be removed.