Paper Number
VP57 

Session
Pre-recorded Flash Presentations (virtual)

Title
Application of high pressure shear rheology to assess CO₂ gas bubble nucleating proficiency of native starch particles and dispersed proteins

Presentation Date and Time
All Week (Asynchronous) Any Time

Track / Room
Pre-recorded Presentation / Virtual

Authors (Click on name to view author profile)

1. Zink, Joël I. (ETH Zürich, Laboratory of Food Process Engineering)
2. Windhab, Erich J. (ETH Zürich, Laboratory of Food Process Engineering)

Author and Affiliation Lines (in printed abstract book)
Joël I. Zink and Erich J. Windhab
Laboratory of Food Process Engineering, ETH Zürich, Zürich, Zurich 8092, Switzerland

Speaker / Presenter 
Zink, Joël I.

Keywords
experimental methods; applied rheology; biological materials; foams

Text of Abstract
Gas bubble nucleation and its control is one of the most important parameter in industrial foaming applications defining the physical and chemical properties of the end product. It is possible to enhance this processing step by adding gas bubble nucleation supporting agents. In this work, the potency of corn and potato starch as bubble nucleating agents as well as whey protein concentrates and isolates for low-temperature high pressure (HP) foaming applications have been evaluated. In a first work step, the physical properties of the starches were assessed using scanning electron microscopy (SEM), Washburn rise method, nitrogen adsorption, H_g porosimetry as well as light scattering and compared to those of talcum, a well know and widely used nucleating agent in non-food systems. Secondly, the effect of the addition of these starch particles on CO₂ gas bubble nucleation in highly viscous watery hydroxy-methyl-propyl-cellulose dispersions was determined applying HP rheology. Results of the surface properties evaluation suggested that the investigated native starch particles are suitable natural nucleating agent for HP foaming applications but are less efficient than talcum particles. The applied HP rheology technique developed to measure the critical supersaturation revealed, that the starches can compete with the talcum. Moreover, it was shown that the CO₂ gas bubble nucleation was dependent on the source of whey proteins, the concentration of these proteins in the investigated dispersions as well as on the applied shear rate. These findings also allowed to validate the suitability of HP rheology to investigate gas bubble nucleation under defined shear conditions thus, enabling new insights into the mechanism of this process for low-temperature foaming applications in food and pharmaceutical product systems.