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In vitro investigation of digestion of a bread and cheese meal by MRI
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Edité par CCSD -
International audience. Gastrointestinal digestion is a complex dynamic process consisting of mechanically and enzymatically breaking down the food structures into nutrients which are usable by the organism. Monitoring food degradation during the different digestion phases is essential for understanding the mechanisms regulating the digestion of specific nutrients and the impact of food structure on nutrient absorption. In last years, in vitro systems simulating digestion processes [1] have been developped, making it possible to resolve several difficulties associated with in vivo experiments, espetially biological complexity and ethical concerns. MRI is a highly promising non-invasive approach for both in vivo and in vitro digestion research [2] as it can be used to obtain information on the status and amount of water and lipid protons in foods. These information can be used for spatially resolved measurements of multi-scale structural features and composition of food, as demonstrated in recent studies on simplified food such as gelsThe present study aimed to evaluate MRI for monitoring digestion of a complex meal composed of bread, cheese and water. All macronutrients (saccharide, protein, lipid) were gathered in such a meal, with particularities: bread samples containing mainly starch and to a lesser extent (10%) proteins while cheese mainly contained proteins and lipids. Food destructuration associated to erosion and hydrolysis were studied using a semi-dynamic protocol simulating a gastrointestinal human digestive cycle. The study was performed on a 1.5 T MRI scanner (Avanto, Siemens). Evolution of morphological and physico-chemical properties of the particules and the liquid were investigated using: 1) 2D T2 maps 2) 3D fat fraction maps obtained by water-fat separation approach and 3) 3D morphological images obtained by ultra short echo time sequence. Combining different MRI image modalities (Fig. 1), it was possible to investigate separately several phases of the digesta, i. e. supernatant, large food pieces (cheese and bread crust) and molecules or small fragments in suspension which laid deposited at the bottom of the vessel during the MRI measurement.
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