The wall fridge that you can buy and place inside a player house doesn't stop spoilage at any rate. It should, it's design and crafting description all point to it being a working refridgerator.
Steps to Reproduce
Buy a house. Buy a wall fridge. Put one spoiling item in the fridge, and one somewhere that spoilage is at it's normal non refridgerated rate. After 1 or 2 days, pick up the item that you put in the fridge, then put it down. Pick up the item that was non refridgerated. They will have the same spoilage time on them.
This issue has not been confirmed by a developer yet.