I'm not really sure how to train a dog to take food gently...

Daphne is VERY gentle when she takes food. No one ever trained her that though. You could have your hand covered in meat (um, somehow. it's just theoretical! lol) and she'll lick it off, and you won't get a scratch.

My mom's dog on the other hand, will bite your whole hand off. And she's a little 10lb Shih Tzu! We just drop treats on the floor or in her bowl for her.

The only thing I can think of is to train him to catch the treat, or teach him 'wait' and put the treat on the ground or something, then tell him 'okay' when he's allowed to eat it.