Smartphone-assisted low-cost paper-based colorimetric and fluorescent dual response sensor for visual evaluation of food freshness

Abstract

Biogenic amines are critical food spoilage indicators, yet their on-site monitoring remains challenging. This study reports a smartphone-assisted, low-cost paper-based tag (BOH@tag) for the visual assessment of food freshness through a colorimetric and fluorescent dual-response to biogenic amines. The tag exhibits a distinct color transition from yellow to magenta upon reaction, high sensitivity (detection limit: 2.09 μM for cadaverine), rapid response (10 s), excellent selectivity, and a large color difference (ΔE = 134), enabling clear naked-eye and smartphone based readout. Its practical utility is demonstrated by real-time monitoring of shrimp and chicken breast freshness under various storage conditions. This work provides a simple, portable, and reliable platform for on-site food quality surveillance.