A method for the non-invasive measurement of the gas content of at least one gas selected from O 2, CO 2, amines, nitrogen oxides, sulfur compounds, in transparent packages made of plastic films, in which a sensor sensitive to the gas content in the interior of the package is excited by excitation light incident thereon to emit a fluorescent or luminescent light, the emitted fluorescent or luminescent light is detected in a detection device interacting with the sensor, whereupon the packaged materials or produced materials are subjected to sorting, and optionally counting, as a function of the gas content determined by an evaluation unit coupled to the detection device, characterized in that the following steps are performed: a) optionally deep-drawing the package; b) applying a sensor material to the inner side of a cover for the package, or to the inner side of the package, and optionally drying the sensor material; c) introducing into the package the materials to be packaged; d) gas-tightly closing the package by the cover while introducing a modified atmosphere of the gas to be measured; e) placing the package on a conveying and sorting device; f) exciting the sensor material by at least one excitation light source arranged at a defined distance from the package; g) detecting, in a contactless manner, the intensity of the fluorescent or luminescent light emitted by the sensor material as a function of the gas content in the interior of the package, by a detection device arranged at a defined distance from the conveying device during conveying of the package to the sorting device; h) electrically or electronically converting in the evaluation unit a measurement value detected in the detection device; i) applying a pressure to the package; j) performing steps f) to h) again; k) outputting a confirmation signal or a rejection signal by the evaluation unit; and l) forwarding the package to further processing or disposal as a function of the gas content in the package calculated by the evaluation unit. a) optionally deep-drawing the package; b) applying a sensor material to the inner side of a cover for the package, or to the inner side of the package, and optionally drying the sensor material; c) introducing into the package the materials to be packaged; d) gas-tightly closing the package by the cover while introducing a modified atmosphere of the gas to be measured; e) placing the package on a conveying and sorting device; f) exciting the sensor material by at least one excitation light source arranged at a defined distance from the package; g) detecting, in a contactless manner, the intensity of the fluorescent or luminescent light emitted by the sensor material as a function of the gas content in the interior of the package, by a detection device arranged at a defined distance from the conveying device during conveying of the package to the sorting device; h) electrically or electronically converting in the evaluation unit a measurement value detected in the detection device; i) applying a pressure to the package; j) performing steps f) to h) again; k) outputting a confirmation signal or a rejection signal by the evaluation unit; and l) forwarding the package to further processing or disposal as a function of the gas content in the package calculated by the evaluation unit.