Container design.
Do you remember when did you put tomatoes in your refrigerator?
People? throw way food too easily, JUST they didn't know that there are it in a refrigerator or when did they put them in refrigerator.
If You can make a rough guess when did you put food in a refrigerator, you don't have to dump your food indiscreet.
A surface of container that I propose, changes colour to dark and dark by Maximum period of one month from the day you start to put food in your refrigerator. one month later, container changed dark. That means, you throw away rotten food. if you want to restore your container, you can it in water anytime.
Like litmus paper, this container informs people who they put food at rovers in refrigerator.