Porphyrin-based sensor films for monitoring food spoilage

To increase food safety and to minimize food waste, it is interesting for the food industry and consumers to be able to determine food spoilage continuously and non-destructively. When food of animal origin is degraded, amines are released as protein breakdown products, which could be used to monitor the freshness of meat and fish. In this work, we introduce a porphyrin-based sensor foil aimed at the detection of biogenic amines. The sensor-porphyrin is formulated on mesoporous silica. Reactivity towards moderate humidity was eliminated by dispersion of the functionalized silica in polyethylene (PE), followed by thermal extrusion resulting in PE foils. After exposure to amines, the sensor foil changes its color irreversibly from green to red. The color change is accompanied by a pronounced shift of the fluorescence spectrum, which was used as a sensitive method to detect the degradation of fish products in model experiments. Titanium dioxide particles in the foil increased the detected fluorescence emission. Experiments with fish filets showed the applicability of the sensor foils in a real-life application by indicating the degree of spoilage after several days, while the microbial growth was depicted by total viable count. We anticipate that our sensor can be an integral part of smart food packages, helping to track the freshness of food during transport or storage.