A simple sensor system for onsite monitoring of o₂ in vacuum-packed meats during the shelf life

Vacuum packaging (VP) is used to reduce exposure of retail meat samples to ambient oxygen (O₂ ) and preserve their quality. A simple sensor system produced from commercial components is described, which allows for non-destructive monitoring of the O₂ concentration in VP raw meat samples. Disposable O₂ sensor inserts were produced by spotting small aliquots of the cocktail of the Pt–benzoporphyrin dye and polystyrene in ethyl acetate onto pieces of a PVDF membrane and allowing them to air-dry. These sensor dots were placed on top of the beef cuts and vacuum-packed. A handheld reader, FirestinGO2, was used to read nondestructively the sensor phase shift signals (dphi^◦ ) and relate them to the O₂ levels in packs (kPa or %). The system was validated under industrial settings at a meat processing plant to monitor O₂ in VP meat over nine weeks of shelf life storage. The dphi^◦ readings from individual batch-calibrated sensors were converted into the O₂ concentration by applying the following calibration equation: O₂ (%) = 0.034 * dphi^◦2 − 3.413 * dphi^◦ + 85.02. In the VP meat samples, the O₂ levels were seen to range between 0.12% and 0.27%, with the sensor dphi signals ranging from 44.03^◦ to 56.02^◦ . The DIY sensor system demonstrated ease of use on-site, fast measurement time, high sample throughput, low cost and flexibility.