Korean scientists have invented a sticker that shows bad food. The study is published on the Wiley Online Library website.
So far, a sticker from experts at the Korean Chemical Technology Research Institute (KRICT) indicates products that were stored in violation of their temperature regimes — for example, frozen fish, meat, fruits, and vegetables that were subsequently frozen again.
The sticker will begin to appear on the product if it has been exposed to temperatures above 10°C. When such products are exposed to room temperature, bacteria begin to multiply there quite quickly. Many of them do not affect the smell or taste, and such products have the same appearance even after a cycle of freezing and thawing.
The device is a nanofiber film – at low temperature, its structure remains stable, and at room temperature, it begins to break down and melt.
The cost of such a sticker is very low, and you can produce it quickly enough, so scientists hope to bring the device to a wide market soon.