Dr. Ozmium Krypton Boomer’s explosive lab accident gave him the ability to conjure fire and explode himself without harm. This changed his biology, so now everything he eats is burned up and vented as smoke.

I think his sense of taste could have dulled somewhat since his accident. I imagine Oz really loves anything spicy because it’s a strong taste and he can eat it without any ill effects. He also loves soda because it has a overpowering sweet taste.