To detect biogenic amines produced during food spoilage, ZenxTag designed and developed a smart food label, based on a complex that can quickly response to biogenic amines. Without contacting the food, the label changes from dark green to orange-red when the food decays. Unlike traditional chromatographic methods and electronic sensors, this smart label is passive and low cost, and responds quickly and reliably. It has promise for use in the consumer end-market to ensure food safety and in the food industry to reduce food loss.