Real-Time Fluorescence Screening Platform for Meat Freshness

Meat's freshness is closely related to food safety and human health and has received increasing attention nowadays. To on-site visually screen meat freshness in a fast and non-destructive manner, we rationally constructed a series of fluorescent probes (JDCN, JDNS, and JDPY) with distinct electron-withdrawing substitution groups based on julolidine-fused coumarin. These probes underwent an aza-Michael addition followed by an elimination reaction with cadaverine to generate a colorimetric and ratiometric fluorescence response, and their sensing performance was rationally enhanced by improving the electron-withdrawing strength of substitution groups. Particularly, JDCN with a dicyanovinyl group as the reaction site exhibited outstanding sensing performance including rapid response (∼60 s), high selectivity, and low detection limit (14 nM). Furthermore, JDCN was fabricated into test kits to detect cadaverine vapor with a high-contrast fluorescence change from red to green. Based on two-color visualization of cadaverine vapor, on-site non-contact and non-destructive monitoring of meat freshness was successfully achieved. The good sensing performance rendered JDCN test kits a promising real-time fluorescence screening platform for rapid, non-destructive, and accurate evaluation of meat freshness.