Effect of kneader geometry on the alveolation and texturing of bread dough

Dans le procédé de panification, la phase de pétrissage est une des plus importantes et va conditionner en grande partie la structure finale du produit céréalier. Ce travail s’est intéressé à l’impact de la géométrie du pétrin et des conditions opératoires sur les caractéristiques de la pâte à pain. Pour ce faire, quatre pétrins de deux géométries (simple et double outil) et de deux échelles (laboratoire et industrielle) ont été étudiés. Ces pétrins ont été définis grâce à des facteurs (puissance, cisaillement, mélange etc.) les caractérisant. L’étude a permis de quantifier le taux de cisaillement par différentes approches (échelle globale à locale) et de mettre en relation l’influence de la géométrie sur cette grandeur. Les caractéristiques de la pâte ont été étudiés principalement selon deux paramètres, l’aération et la structuration. Ces deux paramètres évoluent avec les phases du pétrissage et les conditions opératoires. L’impact du pétrissage sur les liaisons chimiques a été étudié par Microscopie Confocale à Balayage Laser (MCBL) et par les spectroscopies vibrationnelles Proche Infrarouge et Raman. Les caractéristiques hysicochimiques des pâtes ont ensuite été étudiées à un même niveau de pétrissage en variant les entrefers au fond de cuve, à la paroi de la cuve et inter-outil et sur tous les pétrins, mettant en évidence un effet de l’échelle et de la géométrie. L’ensemble des résultats a permis de déterminer les paramètres clefs qui conditionnent la structure du réseau de gluten formé au pétrissage. Enfin, un indice de performance de pétrissage a été développé afin de pouvoir classer les pétrins selon leur efficacité de mélange et leur rendement énergétique.In the bread-making process, the mixing phase is one of the most important and will largely determine the final structure of the cereal product. This work focused on the impact of the geometry of the mixer and the operating conditions on the characteristics of bread dough. To do so, four mixers of two geometries (single and double tool) and two scales (laboratory and industrial) were studied. These mixers were defined by factors (power, shear, mixing, etc.) characterizing them. The study quantified the shear rate using different approaches (global to local scale) and related the influence of geometry on this magnitude.The characteristics of the dough were studied mainly according to two parameters, aeration and structuring. These two parameters change with the phases of kneading and the operating conditions. The impact of kneading on chemical bonds was studied by Confocal Laser Scanning Microscopy (CLSM) and by Near Infrared and Raman vibration spectroscopy. The physico-chemical characteristics of the doughs were then studied at the same kneading level by varying the air gaps at the bottom of the tank, at the tank wall and between tools on all kneaders, highlighting an effect of scale and geometry. All the results made it possible to determine the key parameters that condition the structure of the gluten network formed during kneading. Finally, a kneading performance index has been developed in order to classify kneaders according to their mixing efficiency and energy efficiency

Bread dough preparation in a mixer; impact of mixing process on dough properties

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Benchmarking of techniques used to assess the freeze damage in potatoes

International audienceIn this study, benchmarking of methods used for assessing freeze damage in potatoes was carried out. Initially, the samples were frozen by subjecting them to three different temperatures (i.e. at -18 °C, -30 °C, and at -74 °C). Then, different analytical techniques comprising of focused methods (i.e. cryo-Scanning elctron microscopy-cryo-SEM, confocal laser scanning microscopy-CLSM) and global methods (i.e. texture analysis, low field nuclear magnetic resonance (NMR), exudate loss and colour change) were used to assess the impact of the freezing treatment from the different point of view addressed by each method. As a result, each of these methods were able to distinguish significantly fresh samples from the frozen-thawed samples. Focused methods like cryo-SEM and CLSM methods could differentiate the impact of all three different protocols. Meanwhile, texture analysis (including conventional method and novel method based on a touchless laser puff firmness tester), NMR and exudate loss could only determine the quality difference between -18 °C and -74 °C freezing conditions. Colour analysis was found as an inappropriate parameter for comparing the three freezing protocols. Among all analytical techniques, cryo-SEM provides the most authentic information about the product as the analysis is performed in frozen state, while for other techniques the product is thawed prior to analysis

Bread dough preparation in a mixer; impact of rotation speed and of energy on selected dough properties

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A multiscale approach to understand dough microstructure formation during process; from protein network to dough rheology

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Modelling rheological dough behaviour from an innovative air-puff system

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Evaluation of bread dough aeration during kneading by an air-jet impulse system

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Modelling of dough aeration during bread dough mixing; impact of process parameters on dough aeration and bread structure

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Cluster and Ground-based Observations of The Cusp For Variable Imf and Quiet Conditions

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Cluster and Ground-based Observations of The Cusp For Variable Imf and Quiet Conditions

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