Texture de la purée de pomme : influence de la structure sur les propriétés rhéologiques et la perception sensorielle - effet du traitement mécanique.

Abstract : Fruit purees are considered as concentrated dispersions of deformable and insoluble particles in a continuous phase or serum rich in water, sugar and soluble pectin. The dispersed phase consists of cells or cell clusters of parenchyma tissue and the insoluble cell wall material dispersed in the serum represents a very low weight (~ 1% w/w). The structure and the rheological properties of purees will depend on many internal factors such as the variety and ripeness of the fruit and external factors occurring during the processing (mechanical and thermal treatment). Texture is a key quality attribute of purees and thus constitutes an important potential source for new product development. The main objective of this study was to better understand the relationship between the rheological, structural and sensory properties of apple puree, in order to pilot and control the texture of the products. The study was performed with a single batch of apple puree prepared industrially from fresh mature Golden Delicious. In order to create purees with varied structure and texture, three structural parameters were identified and modified: the cell walls concentration (related to the amount of pulp), the particle size and the viscosity of the continuous phase. A separation-reconstitution strategy joined to a grinding step and the modification of the serum viscosity allowed us to obtain a wide range of products with different structures and textures. The construction of two experimental designs made it possible the controlled preparation of the products so as to study the relatioins between structure, rheology and texture of the apple puree. Physical and sensory characterization highlighted the importance of structural parameters on the rheological behaviour and perception of the texture of the puree. Thus, the concentration of particles is the main parameter influencing these properties, followed by the particle size and the serum viscosity. The increase in particle content translates directly at the “overcrowding” that also depends on the particle size. Mechanical treatment leads to the separation of clusters of parenchyma cells in to individual cells; this change in structure involves marked changes of properties. Rheological and structural characterization made it possible the generation of rheological models and the better understanding of the behaviour, the state and the role of particles (soft and deformable) on the structure of the medium and the volume occupied by them. This approach has been completed and validated by the observation of dispersions by various microscopic techniques. The different regimes of concentration were identified. Texture perception of apple puree can be described basically by their “consistency” and their “graininess”. The viscosity of the continuous phase has an impact on the perception of “graininess” and in the cohesion of the particle network. Our results show that the texture of plant food dispersions can be “mastered” by controlling a few selected key parameters: the concentration of cell walls (pulp) and particle size, completed by the viscosity of the continuous phase. High possibilities for innovation are opened by playing on these parameters that can be modified during the processing.
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Lucia Carolina Espinosa Munoz Brisset. Texture de la purée de pomme : influence de la structure sur les propriétés rhéologiques et la perception sensorielle - effet du traitement mécanique.. Alimentation et Nutrition. AgroParisTech, 2012. Français. ⟨NNT : 2012AGPT0008⟩. ⟨pastel-00749695⟩

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