Here's a secret little trick I learned from my mother.
Baking soda naturally absorbs odors. Due to its alkaline nature, it actually neutralizes acidic odors in particular. However, a box of baking soda doesn't do a great job on its own because there is such a small surface area within the box. Try spreading the baking soda on a sheet pan. That should do the trick.
Better yet, activated charcoal absorbs odors extremely well. You can purchase this at any pet store, and it is already broken up into small bits to increase surface area. Everyone can appreciate a clean fridge!