Some of it can be controlled with how you hold the food. Place it in your hand close to your thumb and cover it with your thumb to trap it there. When you want, you can roll your thumb back to allow access to the food. Your hand can be open except your thumb do the dog can't bite anything.
This video shows teaching impulse control which can help too. I don't do this too much as I want the dog pushing into my hand for the food.