A versatile development platform for odor monitoring systems

The measurement of odors offers a high potential for non-destructive, on-line, real-time quality monitoring of many different products, such as food and cosmetics. Although numerous laboratory devices are capable of such odor measurements, required laboratory background and trained workers prevent the widespread use of such devices in the industry and in public. Hence, cheap and commercial instrumental odor monitoring systems (IOMSs) are needed. To ensure a timely and cost-effective experience during the development of such IOMSs, a gas chromatography selective odorant measurement sensor array (GC-SOMSA) combining three detector ports (a mass spectrometer, an odor detection port, and a sensor chamber) is set up as an element of a structured development concept for IOMSs. This device is tested with a commercially available sensor and spiked sunflower oils, which emulate odor-active oxidation of fatty oils that occur during oil aging in food or cosmetics. The sensor was able to detect pentane (4 µL 100 mL-1) and the odor-active oxidation markers hexanal (1.4 µL 100 mL-1) and octanal (8.2 µL 100 mL-1) within a sunflower oil matrix. When applying different sensor temperatures, the sensor was able to detect a more intense signal for hexanal than for pentane at 250 °C. Furthermore, it was found that the (siloxane) protective membrane of the sensor discriminates between different molecules. This has an influence on the synchronicity of the detectors by adding a possible time offset to the sensor signals. This offset could be considered by forming the first derivative of the sensor signal. The odor detection port measurements revealed a weak odor impression at calculated target concentrations. For 10 and 100 times higher concentrations, hexanal (grassy) and octanal (citrus-like) could be detected. All three detectors were in parallel, and odor impressions could be assigned to mass spectrometer and sensor peaks. Thus, the sensor could be characterized sufficiently and is suitable for detecting odor-active compounds in the fat oxidation of a fatty matrix. The GC-SOMSA can be used in the future as an element of a structured IOMS development concept since it can be extended to a wide range of applications for rapid sensor characterization and, due to the flexible design of the sensor chamber, for many different sensors.