| Biopolymers | ||
| Biopolymers are commonly added to foods, and other products in order to provide structure stability and specific textural properties. Mixtures of two biopolymers in aqueous solution can generate a two-phase biopolymer emulsion. If one of the two biopolymers is gelling, and enriches in the dispersed phase, biopolymer suspensions (gelled emulsions) can be formed. The particle shape represents one of many parameters that influence the rheological behavior of suspensions. Of particular interest here are regular spherical, or cylindrical particle shapes, which were produced by subjecting two-phase biopolymer mixture to a thermodynamic non-equilibrium process coupled with steady and oscillatory shear experiments. | ||
| Projects | ||
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| This work focuses on controlled Taylor-made particle shape, and, hence, microstructure-rheological relationships for food emulsion/dispersion systems as biopolymer mixtures. The time-dependent evolution of the gelation process including the formation of non-equilibrium shapes of the suspension/emulsion particles shall be investigated with a new stress- / strain-controlled rheometer and an adapted rheo-optical set-up. The work is concerned with investigating the microstructures in phase-separated biopolymer mixtures with the specific aim of influencing the rheological behavior. Within the research project, the rheology and rheo-optics of emulsions and other multiphase systems will be studied in different flow fields. The objective is to investigate: - The microscopic local behavior (rheo-optic) of the dispersed and continuous phases of an immiscible multiphase fluid under different flow conditions. - The resulting effect of this properties on the macroscopic rheology and macro-structure of the emulsion/dispersion system. We propose a new rheometer because with the existing once we cannot properly investigate complex change of the material investigated. This is due to (1) geometrical restrictions, (2) slow electronically control system, and (3) restriction of available rheological test proceedures of both existing rheometers. Consequently, the task of the up-coming investigation of non-equilibrium shaped emulsion/suspension systems and of rheometrical flow structured mixing cannot be accomplished without a upgrade in instrumentation. Especially, rheo-optical investigations as a powerful tool to add structural information to flow behavior and therefore a tool to sufficiently understand the complex nature of such structures cannot be implemented in the existing rheometers. Dr. Peter Fischer (peter.fischer@ilw.agrl.ethz.ch) |
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