There has been some lame attempts by slapping a LCD panel on the front with an RFID scanner, but you still have to remember where you store the food.

A good user interface could solve this, even without the RFID scanner. The touchscreen would display items in refrigerator, sorted by shelves.

Adding a new food: click "new food" icon, select the food from the list, click on the shelf. (You are supposed to do this after you have put the food inside.) Now the panel displays the food on the correct shelf.