Fadink / carton

With a special kind of ink printing on food packages,we are able to create a brand new way to save the Earth's resources.The ink is fading over time right after it's printed and the package becomes blank when the food inside is no longer fresh.Surely, we can control the time of its fading out accurately.
It is easy for people judging by the package of foods to know whether they are going bad,which will lead people to deal with the food in time and avoid the waste of food.