Designer Naoki Hirota was fed up accidentally buying stale meat and other food items that had reached their expiry date. When you're shopping in a rush, you can't afford to spend too much time examining each and every item. You tend to rely on the store's management to make sure the offered goods are fresh and good for consumption, but that's not always the case.
In order to put an end to this, Hirota came up with a creative label concept that ensures you don't end up with bad meat anymore. The labels are designed to change color over time, so when they reach the expiry date, the barcode is obscured, making it impossible to scan at the checkout.
The label has two layers, one that has printed information for the featured food item, and another on top with special ink that is made of a non-toxic, safe pigment derived from purple cabbage that is reactive to ammonia.