OxInA

Fat-containing dry products such as powdered milk, flour, pulses, dried fruits and seeds play a central role in the global supply chains of the food, feed and cosmetics industries. Unfortunately, loss of quality due to oxidation during storage, transportation and processing can be a problem with economic, health and environmental consequences, as well as direct losses to businesses. The fact that fat oxidation products have specific marker compounds that are directly related to their quality (i.e. the higher the oxidation, the lower the quality) has been researched at Fraunhofer IVV for some time. For example, atmospheric oxygen and light can trigger lipid peroxidation. The radical reaction produces degradation products such as aldehydes, lactones, alcohols, ketones, carboxylic acids and many more. These degradation products can cause off-flavors that are perceived as rancid, fishy, bitter, or pungent, thus reducing product quality. Instrumental monitoring and quantification of such markers can therefore provide an objective criterion for early assessment of raw materials. Since conventional analytical methods are often too expensive for in-line or on-line analysis, a low-cost sensor system can be used instead, e.g. during storage, transport or incoming goods. However, such a system must be able to detect and quantify the individual oxidation markers in food reliably and free from possible environmental interferences.

In the OxInA project, relevant marker compounds are identified and tested on different sensors. For this purpose, the "gas chromatography – selective odorant measurement by sensor array" (GC-SOMSA) system installed at the IVV is used. It has a classical mass spectrometer (MS) and a parallel olfactometry port. In addition, a third port is connected in parallel to which different sensors can be connected. This parallelization makes it possible to detect a substance with the MS, assign it to an odor with the olfactometry port, and also determine and compare the reactions of the tested sensors to the corresponding markers. In addition, the sensors can be directly compared to each other to determine the most appropriate sensor for the respective markers. Using the markers previously identified in a literature search, an artificial mixture can then be prepared as a standard for "oxidized raw materials" and compared with real samples. Based on the results of the GC-SOMSA measurements and the literature research on known oxidation markers, a general guideline for the analytical transfer of GC measurements in quality control and their results to sensors and sensor systems will be developed in order to be able to quickly and efficiently develop application-specific measuring systems in the future and thus enable the automation and optimization of process control in a wide range of applications.