Leftover food containers that auto-detect food contamination
A system of leftover food containers and measurement devices
One solution is a device which measures the amount of harmful bacteria present in food, like this : http://www.foodsafetynews.com/2013/11/personal-handheld-sensors-to-detect-pathogens-could-be-the-future/#.V5ZgxpMrKRs
It is also possible to package leftover food in containers that change their state in some way, if bacteria is present : http://www.food.dtu.dk/english/News/2015/06/Method-provides-more-knowledge-about-harmful-substances-in-food-packaging?id=1fe3b5a0-8c76-4ee5-9fd5-a803878eda4f
It will then be possible to employ a lawyer at the start in order to approve the technological food bacteria detection solutions. This could ensure that leftover food is always fresh enough for consumption.
Bacterial contamination is just one type, there are other types of food poisoning. Moreover, the food spoilage involves more than just bacteria -- enzymes, oxidation, mold, yeasts,...
I've renamed the idea from 'Hardware solution', because idea names have to be self-explanatory without context.