Show me its volatile profile and I will tell you its quality : rapid fingerprinting of food volatilome at the boundary between food industry and sensory perception

Food industry is searching for rapid and flexible instrumental tools to support sensory evaluations for quality control of food products. Monitoring volatile organic compounds (VOCs) from farm to fork through direct injection mass spectrometry techniques seems a promising possibility. This thesis focuses on the aspects of food quality related to the sensory part of aroma by presenting different applications of proton transfer reaction mass spectrometry (PTR-MS) for headspace and in vivo nose-space analysis. PTR-ToF-MS was used in combination with a selective reagent ionization device (SRI) and multipurpose autosampler for obtaining, through a rapid and non-invasive headspace analysis, VOCs fingerprint of different food matrixes like anhydrous milk fat (AMF), ultra-high temperature lactose-free milk (UHT LF milk) and raw hazelnuts. The results of Chapter 2, 4 and 5 confirmed that PTR-ToF-MS fingerprinting is a valid sensitive approach to collect information about VOCs evolution during shelf life at different conditions and to monitor degradation processes which can compromise food quality such as lipid oxidation. Results from Chapter 3 and 5 demonstrate that VOCs fingerprints can be used for supporting sensory quality control in agroindustry since both unsupervised and supervised data mining approaches gave positive results in discriminating sensory classes assigned through industry sensory tests. For both tested raw materials (AMF and raw hazelnuts), the good quality samples had lower concentrations for most of the detected mass peaks in VOCs fingerprints.

Chapter 6 and 7 demonstrated the potentialities of coupling PTR-QiToF-MS in vivo nose-space analysis with dynamic sensory analysis to better investigate the complex relation between aroma release and perception and the impact of product and consumer characteristic on this relation. Chapter 6, showed that when consuming composite foods, decrease in sensory intensity perception was not due to a lower delivery of aroma compounds into the nasal cavity, as in-nose aroma release of condiments increased with the presence of a carrier food. Consequently, cognitive effects are likely to play a key role in sensory perception of composite foods. In Chapter 7, the same approach gave indications that consumers origin may affect aroma release and perception of mint chewing gum. Participant’s origin (and diets) may be responsible for physiological differences especially in terms of saliva composition and oral/nasal microbiota. If these observations would be validated by larger population studies, they would be of great interest for the new emerging field of personalized product design and nutrition. In conclusion, PTR-MS approach was proofed to be one example of technological application, which can greatly facilitate the understanding of the factors affecting food quality from agricultural raw materials to market food products.