Imaging (using µtomo-XR) of the mechanisms involved in creating an alveolar structure

Free growth of bubbles, interaction of bubbles then coalescence, limited by the liquid phase (liquor) of the dough forming films <15µm thick [46]. The characteristics of honeycomb structures, including connectivity, and their evolution were determined by analysing images of extruded products [34] and bread-making products to link the micro and macroscopic scales [44]. The definitive acquisition of the honeycomb structure corresponds to the setting of the matrix during baking, or the dough-mix transition, without significant modification of the honeycomb characteristics, and in a temperature range (55, 70°C) where the swelling of the starch and the thermoreticulation of the gluten occur simultaneously [46].

While the contribution of intrinsic mechanical properties is decisive in the case of real products such as cornflakes [38], those of apparent density and entity shape are also important for breakfast cereals and particulate products in general [31]. The production processes are also the subject of simple thermomechanical models based on balance equations. The most advanced example concerns twin-screw cooking-extrusion using Ludovic© software [1], recently applied to real formulations [x1], which will be supplemented by simulation of bubble growth using FEM-3D [15]. Given the importance of know-how in the food industry and the complexity of the phenomena, which are difficult to tackle using deterministic modelling, bread-making operations have been the subject of an approach integrating technological and scientific knowledge, using qualitative algebra [8], which could be extended to other operations and other sectors.

[1] http://www.inra.fr/cepia_eng/you_are_looking_for/platforms_and_tools/softwares/ludovic