We have a bit of possesion aggression with Oscar. He bit my 2 year old when he was very young over a pigs ear.

My trainer advised - Ensure all toys, chews bones are not left lying around (they belong to you and you decide when to play)

You need to correct the behaviour when it is a thought in his head so the moment he rumbles you say "NO" or "Uh UH" I don't necessarily agree with removing the food because i was told it might make them worse and the growl is a warning and if they think you are going to ignore the warning they will not give one and just bite.

I ensure all feeding and chews are out of the children way now to avoid a disaster and i do excactly what you have done (make him sit, move the bowl mid meal etc).

Something else to do is while he is eating PUT FOOD INTO HIS BOWL. Add something MORE tasty than his meal that way he will associate you being close to his bowl with recieving a treat rather than having something taken away.

I think it is something you always have to be aware of and work with