I'm not going to be able to eat food that my husband burped on
Oh no! How do you know that your husband burped on it? That sounds pretty gross.
He burps on food as a joke
It's horrible that your husband does that and I understand why you wouldn't want to eat it. You should tell him to stop and that it isn't funny to burp on people's food.
He's doing it just to annoy me. Maybe I'll get mad at him.
Talk to your hubby first, burping on food sounds quite childish to me. Most likely he will stop, he is not really funny. Tell him that and then get mad if he doesn't "get it" (not the joke but your reasoning).