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Effect of high shear rates on physico-chemical characteristics, rheological behavior and fouling propensity of orange juices during cross-flow microfiltration

Dahdouh L., Delalonde M., Ricci J., Rouquie C., Wisniewski C.. 2016. In : Book of abstracts of the food factor 1 Barcelona conference, 2-4 November 2016, Barcelona (Spain). Barcelona : Formatex Research Center, p. 258-258. The food factor 1 Barcelona conference: Established, emerging and exploratory food science and technology. 1, 2016-11-02/2016-11-04, Barcelone (Espagne).

Microfiltration is broadly used in fruit juices industries to ensure clarification and sterilization of many fruit juices or to concentrate their pulpy fraction. However, the industrial application of microfiltration in fruit juice industries remains hampered by the decrease of membrane permeability during the operation, due to the fouling mechanism. To increase technological feasibility and economical productivity, fruit juices microfiltration is generally performed using tubular membrane under high crossflow velocities, with the aim to limit particles deposition. Indeed, high shear rates close to the membrane surface can reduce membrane fouling by reducing particles deposition, but under these hydrodynamic conditions large compounds, present in the bulk suspension, can be fractionated into smaller particles. Since fruit juices contain cell fragments, colloidal aggregates, etc. this fractionation can release new compounds characterized by a high fouling propensity. The aim of this work was to study the impact of high crossflow velocity on orange juice characteristics, i.e. particles size distribution, insoluble particles cohesion energy and overall fouling propensity. A raw orange juice (produced locally) was subjected to a shear rate of 2.105 s-1 (without filtration) using a pilotscale filtration unit (TIA, Bollene, France). Laser diffraction was used to determine the impact of this shear rate on the particles size distributions of the orange juice. Dynamical rheological measurements, according to the strain amplitude sweep test, were realized on the insoluble compounds of the raw and the sheared juices. The obtained complex moduli and critical yield stresses were used to calculate the energy of cohesion of the network of this class of particles. Finally, the fouling propensities of the raw and the sheared juices were determined using a stirred and pressurized lab-scale filtration cell. The obtained results showed that the crossflow velocity changed significantly

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