You never know what is in your fridge, right? This problem mostly occurs for families or living communities that are busy, e.g., because of their work.
The fridge should automatically detect what you have and how much of it. The fridge can sync it to the cloud so, it gives you the information when you need it, e.g., on your way home or in the supermarket. This way, you only need to buy what is missing and you can therefore create tasty meals without increasing waste.
Hardware hacking: Building prototype that weights stuff and identifies it through adhesive RFID tags.
IoT, Arduino, Raspberry Pi, RFID Reader and Tags