Understanding and measuring light-induced oxidation in dairy products

Foods are exposed to light throughout processing, packaging, distribution, and at the retail level. Light-induced degradation of lipids, proteins, vitamins and pigments in foods causes both formation of off-flavors and discoloration, which rapidly impair product quality and marketability and may eventually lead to loss in nutritional value. The food and packaging industry is aware of the problem, but their knowledge about oxidative processes is low, and the information on how to effectively protect agains t light, is scarce. This project will focus on dairy products, which are particularly susceptible to light-induced oxidation. The scientific knowledge on photooxidative processes in dairy products is insufficient. Results from various studies on light exp osure diverge, so it is difficult to serve the industry with reliable advice on how to most effectively take action against this kind of quality degradation. Light induced oxidation has been difficult to measure by means of instrumental methods. Only sens ory analysis, which is very expensive, impractical and time consuming, has been regarded as reliable. A rapid and effective instrumental method to measure the sensory properties associated to light-induced oxidation, would increase the understanding and e nable much more efficient studies of specific foods and packaging materials. This project will approach the problem by identifying the different photosensitizers in dairy products, elucidate their photochemical and spectral properties and how they affect the foods upon light exposure. This is fundamental scientific work, but the results can easily be transformed into practical guidelines for the industry. The results will be of relevance for dairy products as well as other light sensitive foods. A rapid n on-destructive method based on fluorescence spectroscopy will be developed for detection and quantification of light-induced off-flavours, as well as for directly monitoring the degradation of photosensitizers.