AERC2018 and the XV Meeting of the Italian Society of Rheology

April 17-20, 2018 - Sorrento, Italy


Food, Pharmaceutics & Cosmetics

Modelling the viscosity of soft plant particles suspensions

20 April 2018 (Friday) 15:40

Track 4 / Nettuno 1

(Click on name to view author profile)

  1. Leverrier, Cassandre (UMR Ingénierie Procédés Aliments, AgroParisTech, INRA)
  2. Cuvelier, Gérard (UMR Ingénierie Procédés Aliments, AgroParisTech, INRA)
  3. Moulin, Gabrielle (UMR Ingénierie Procédés Aliments, AgroParisTech, INRA)
  4. Almeida, Giana (UMR Ingénierie Procédés Aliments, AgroParisTech, INRA)
  5. Menut, Paul (UMR Ingénierie Procédés Aliments, AgroParisTech, INRA)

(in printed abstract book)
Cassandre Leverrier, Gérard Cuvelier, Gabrielle Moulin, Giana Almeida, and Paul Menut
UMR Ingénierie Procédés Aliments, AgroParisTech, INRA, Massy, France

Leverrier, Cassandre

Apple purees are concentrated suspensions of non-colloidal (180 µm), non-spherical and highly deformable particles. These particles are delimited by a plant cell wall and filled by the continuous phase. Under stress or when the concentration of particles increases, they compress and their volume decrease, making it difficult to determine their real volume fraction and understand their rheological properties. In general, the rheological behaviour of plant particle suspensions is described by three concentration domains, usually modelled separately: a diluted domain in which the particles have little interaction (newtonian), an intermediate domain marked by the appearance of a network between the particles (yield stress fluid behaviour, characterized by an elastic modulus at low deformation which increases strongly with the concentration of particles) and a concentrated domain in which the particles are forced to deform to allow the flow. In this work, we propose a mean to access the apparent volume fraction of plant particles and a model describing the dependence of viscosity on concentration over a wide range of concentrations. The proposed model, adapted from the Mendoza model (Mendoza 2013), fits precisely to the experimental results obtained on apple purées of variable particle size distribution and on model suspensions reconstituted in several continuous phases. Model parameters reflect particle stiffness and asphericity. Finally, by combining confocal microscopy and 3D reconstruction, we were able to show that the volume of cells decreases only in highly concentrated suspensions. By direct observation within the sample, we thus prove the ability of the plant particles to compress and thus reduce their volume when the concentration increases. This work offers interesting prospects for the processed fruit and vegetable industry and has led to a step forward in the modelling of these systems. Keywords: soft particles, suspension, modelling, microscopy