Thesis subject

Structuring by Phase Separation of Biopolymers

Introduction

Food products may be viewed as edible structures that are created as a result of the interactions between the ingredients and processing conditions. Where the structure can be defined as the spatial organization of the building blocks present in foods (Boom and Goot, 2013). Proteins and polysaccharides, often just referred to as biopolymers, are  essential building blocks in food systems. Both proteins and polysaccharides have different functional properties in food products and play an important role in  gelation, foaming, and emulsification. Here we want to focus on the phase behaviour of mixtures of biopolymers. Normally there is a strong tendency for proteins and polysaccharides to phase separate in two separate phases (Grinberg and Tolstoguzov, 1997). One phase rich in protein and the other phase rich in polysaccharide. This phase separation is often useful because it can be used to structure foods on a mesoscopic scale (see images below). This is especially interesting when one of the biopolymers can be gelled and the structure is stabilized. The aim is to better predict the phase behaviour of biopolymers and study the resulting structure and its functionality. When feasible also biopolymers from alternative sources will be studied (i.e. plants, fungi,…). As experimental techniques like osmometry, confocal scanning light microscopy (CSLM) and rheology will be typically used.

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CSLM images of WPI-Gelatin mixtures (Ersch, 2015)

 

Research Topics

  • Study the phase separation in the mixtures of proteins and polysaccharides
  • Study the resulting structure and functionality of the mixtures

 Techniques

  • Characterization (Nano-sizer, Mastersizer, Potentiometric titration)
  • Microstructure (CSLM, NMR, SEM)
  • Rheology (Rheometer, Texture Analyzer)
  • Molecular interaction (Osmometer, Light Scattering)

References

  • BOOM, R. & GOOT, A. J. V. D. 2013. Food Structuring, Wageningen, Wageningen University.
  • ERSCH, C. 2015. Microstructure and Rheology of Globular Protein Gels in the Presence og Gelatin. Protein Mixtures: Interactions and Gelations. Wageningen Wageningen University
  • GRINBERG, V. Y. & TOLSTOGUZOV, V. B. 1997. Thermodynamic incompatibility of proteins and polysaccharides in solutions. Food Hydrocolloids, 11, 145-158.