Kyushu University researchers have developed a self-healing hydrogel that signals spoilage through colour change while extending food shelf life. By immobilising anthocyanins, a natural plant pigment, onto a metal-organic framework, the team stabilised the pigment against light and heat while preserving its pH sensitivity. The material can also repair its own cuts, which helps to keep bacteria out of the food while it progresses through the supply chain. This change is visible to the naked eye, and their natural origin also makes them safe for food contact. Beyond freshness monitoring, the material also extended the shelf life of pork by about 12 hours compared to untreated samples.