Color-changing packaging flags meat spoilage before it’s visible

A packet of meat can look fresh on the supermarket shelf even while bacteria are already multiplying inside. By the time a spoiled smell, discolouration or slimy texture becomes obvious, indicating that the meat has gone stale, the food may no longer be safe to eat.To find a solution to this, researchers at Kyushu University in Japan are working on a packaging material that could give consumers an earlier warning. Their new “smart” hydrogel film changes colour as meat begins to spoil, shifting from purple-red to yellow-green. The flexible material can also repair small cuts in its surface, potentially helping prevent bacteria from entering through damage caused during transport or handling. The research, titled ' Self-healing cellulose-based hydrogel smart packaging embedded with anthocyanin-immobilized metal–organic frameworks for food preservation and freshness monitoring' published in the Chemical Engineering Journal (2026), combines natural plant pigments with advanced porous materials to create packaging that can monitor freshness without requiring the package to be opened, according to a report by Phys.org. Why meat changes as it spoilsFresh meat has a mildly acidic chemical ...