That's why food photography is an art form. Often the actual food is substituted by something that is more resistant to the thermal onslaught of the lighting but that looks identical.

As to the number of takes and food: one particular set I recall was for a cookie brand, they did endless re-takes and the actress that had to eat the cookies started to get sick enough to vomit. We were all pretty happy when the director was finally satisfied with what must have been his masterpiece.