A new biodegradable film made from pectin, gellan gum, and betacyanin from Bougainvillea glabra changes color as mushrooms spoil—shifting from pink to brown in real time. This smart label targets highly perishable species like white button mushrooms (Agaricus bisporus), aiming to reduce waste and give consumers a visible freshness cue. The film also offers antioxidant and antimicrobial benefits, making it a promising eco-friendly solution for intelligent packaging.