Paper Number
IR3 

Session
Interfacial Rheology

Title
Globular protein stabilized emulsions: Effect of the oil

Presentation Date and Time
October 23, 2019 (Wednesday) 2:20

Track / Room
Track 7 / Room 306C

Authors (Click on name to view author profile)

1. Bergfreund, Jotam (ETH Zurich, IFNH)
2. Fischer, Peter (ETH Zurich, IFNH)

Author and Affiliation Lines (in printed abstract book)
Jotam Bergfreund and Peter Fischer
IFNH, ETH Zurich, Zurich 8092, Switzerland

Speaker / Presenter 
Bergfreund, Jotam

Text of Abstract
Globular proteins, such as beta-lactoglobulin, bovine serum albumin, or lysozyme adsorb to oil/water - interfaces. At the interface, the proteins form a viscoelastic layer by intermolecular interactions. The protein's biocompatibility and nutritional value made them essential in pharmaceutic, cosmetic, food, and industrial emulsions. Further, proteins stabilize oil bodies forming lipid storage containers and interfacial protein films serve as a substrate for cell culture proliferation. Therefore, controlling and understanding the formation of interfacial networks of globular proteins at o/w-interfaces is crucial. Effects of ionic strength, pH, temperature and several pre-treatments are well-known. However, the oil phase has been regarded as exchangeable and its role in the protein adsorption mechanisms, interfacial network formation and emulsion stability behavior has been widely ignored [1]. In our recent work, we investigated the influence of systematically selected oils on interfacial protein layers, and emulsion stability was evaluated. Insights into the interfacial network formation and network strength were gained by measuring adsorption kinetic, dilatational and interfacial shear moduli. Additionally, emulsions were formed and characterized over time. We found that depending on molecular size and polarity of the oils, globular proteins adsorb distinctively. Stronger interactions of polar oils with the hydrophilic exterior of the native protein lead to a decelerated protein unfolding. This results in lower surface pressures and slower formation of viscoelastic networks. In addition, polar oils interact stronger with the protein network by hydrophilic bonding and thereby act as softening agents. The effects of oils on the adsorbed protein layers provide knowledge that promotes higher reproducibility in rheological studies and precise tailoring of interfacial films for an enhanced formation and stability of emulsions in numerous fields.
[1] Bergfreund, J et al. Langmuir 2018, 34 (16) 4929–4936