Extruded phosphorescence based oxygen sensors for large-scale packaging applications

Abstract

Extruded phosphorescent O2-sensitive composite materials comprising cross-linked polystyrene-divinylbenzene (PS-DVB) microspheres impregnated with Pt-benzoporphyrin dye and dispersed in low-density polyethylene (LDPE) or polylactic acid (PLA) carrier polymer are described. The sensors produced by hot melt extrusion method are specifically tailored to large-scale packaging applications and non-destructive measurement of residual O2 in packaged food products. A panel of LDPE and PLA based sensor materials in the form of extruded pellets and thin film structures were produced and their structural features and O2 sensing characteristics assessed with the view of packaging applications. The extruded LDPE film sensors were also integrated in packaging materials by heat lamination, to produce ‘smart’ packaging materials which also protect the sensor from direct contact with food. Analytical performance of extruded sensors was demonstrated by incorporating them in modified atmosphere packaged meat and cheese samples and monitoring residual O2 levels in these packs non-destructively with a handheld Optech® reader over product shelf life. The extruded O2 sensors show superiority over the sensors previously used or usable in packaged food products. This technology advances scaled manufacturing of optical O2 sensors, their integration in packaging platforms and cost reduction.