Volatile characterization : Optimizing GC-MS methods to reveal the chemistry and aroma of savoury food ingredients

Volatiles are the responsible for all the pleasant and unpleasant smells on earth. From the delectable honey-crisp apple smell of a Riesling white wine, to the repulsive rotten odour of manure. They are small molecules that have the ability to travel through air and water, and thus, not only can they make food smell good or bad, but also they serve as signalling molecules both within and between organisms. For instance, plant volatiles attract pollinators and seed dispersers, and provide defence against pests and pathogens. For these reasons, measuring and determining the roles of volatiles is crucial in understanding living systems and reaction processes. In food, volatiles comprise thousands of molecules having highly diverse physicochemical properties, which makes the analysis of these compounds highly challenging. Therefore in this thesis we have focused on developing untargeted analytical techniques that improve and broaden the analysis of the vast array of volatiles present in a sample. More specifically, we investigated the application of metabolomics techniques to analyse the volatiles present in natural savoury food ingredients as these are superior flavourful constituents that are used to enhance the aroma and taste of the food we eat, such as soups and snacks. Moreover, work described in this thesis has also explored the intricate relationship between volatile compounds and the aroma characteristics of these food ingredients. The complexity of flavour perception added to the complex volatile profiles and reactions occurring during food processing is described in this thesis. As volatiles are known to contribute the most to the flavour of food, and metabolomics is now growing in application to processed food, this thesis sets the basis for future research into the exploitation of metabolomics technologies and on flavour perception in processed foods and their ingredients&nbsp