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Nutritional and sanitary impact of nuts and seeds roasting: the interest of using fluorescence spectroscopy as a tool to control neoformed compounds

Rita Yaacoub
Abstract : Three main objectives were fixed for this thesis: technological, analytical, and risk analysis objectives. A first objective was to identify critical points of the production chain in terms of the development of oxidation and Maillard reactions, in order to be able to suggest technological solutions to minimize nutritional degradation and accumulation of NFC at these production steps. For this, pertinent indicators of these reactions were monitored throughout the processing stages of nuts and sesame seeds taking into account the quality impact of the raw material. The results showed that, initiated during storage and first stages of nuts and sesame seed processing, lipid oxidation proceeded with processing. Even though several processing stages were involved in the development and amplification of these reactions, roasting appears as a crucial step in the formation of NFC and in defining product nutritional quality. The sterilization step, specifically designed to ensure microbiological safety of the product, contributed also to final NFC load. As a result, the production line should be optimized, particularly roasting conditions and sterilization technology, without compromising microbiological safety and organoleptic quality of the end-product. A second objective aimed at investigating the potential of using front face fluorescence spectroscopy for rapid quantitative estimation of NFC in order to control and improve chemical safety of processed nuts and seeds. To achieve this objective, chemometric analysis of front face fluorescence landscapes obtained from EEM (excitation-emission matrices) acquisition and calibration over the conventionally measured NFC content in industrial samples was applied. The fluorometric analysis revealed detailed information about the molecular changes occurring in these food products when exposed to heat treatment. PARAFAC decomposition models allowed identification of the major parallel profiles forming the front face fluorescence landscape of these products. Results showed that front-face fluorescence is an appropriate tool for monitoring lipid oxidation and nutritional degradation, and that through multiway decomposition of front face fluorescence data coupled with multivariate regression tools, industrial process control and satisfactory NFC calibration models can be achieved. Finally, the actual intake of CML and tFA for an urban adult population (aged 25-64 years) living in Beirut, Lebanon, through the consumption of processed nuts and sesame seed products was estimated. Dietary exposure was obtained by combining food consumption data with CML and tFA levels determined by chemical analysis, and then compared to the levels of concern for each molecule. The estimated average daily exposure to CML and tFA through overall nut and sesame seed products consumption was found to be about 0.76 mg/person/day and 0.32 g/person/day respectively. When compared with levels of concern selected for this study (6 mg/day for CML and 5 g/day for tFA), the average dietary intakes of CML and tFA represented 13 and 7% respectively of the appropriate levels of concern. At the 95th percentile, CML exposure estimates from the only consumption of processed nuts and sesame seeds exceeded the level of concern. The results indicate a potential risk for the high consumers of roasted nuts and sesame seeds and suggest the necessity for a more detailed investigation of exposure to NFC.
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https://pastel.archives-ouvertes.fr/pastel-00005932
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Submitted on : Wednesday, April 14, 2010 - 8:00:00 AM
Last modification on : Monday, October 19, 2020 - 11:11:44 AM
Long-term archiving on: : Friday, September 10, 2010 - 3:02:55 PM

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Rita Yaacoub. Nutritional and sanitary impact of nuts and seeds roasting: the interest of using fluorescence spectroscopy as a tool to control neoformed compounds. Chemical Sciences. AgroParisTech, 2009. English. ⟨NNT : 2009AGPT0048⟩. ⟨pastel-00005932⟩

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