la8b00458_si_001.zip (4.08 MB)
Effect of Oil Hydrophobicity on the Adsorption and Rheology of β‑Lactoglobulin at Oil–Water Interfaces
dataset
posted on 2018-04-04, 00:00 authored by Jotam Bergfreund, Pascal Bertsch, Simon Kuster, Peter FischerThe
adsorption of protein layers at oil–water interfaces
is critical to the formation and stability of various emulsions in,
for example, technical applications as well as in biological lipid
storage. Effects of ionic strength, pH, temperature, and pretreatments
of the proteins are well-known. However, the oil phase has been regarded
as exchangeable and its role in protein adsorption has been widely
ignored. Herein, the influence of systematically selected oil interfaces
of high purity on the formation and properties of β-lactoglobulin
(β-lg) adsorption layers was evaluated. Droplet profile tensiometry
and interfacial rheometry were employed to determine the adsorption
kinetics and dilatational and interfacial shear moduli. We show that
depending on the molecular size, flexibility, hydrophobicity, polarity,
and polarizability of the oils, globular proteins adsorb distinctively.
Stronger interactions of polar oils with the hydrophilic exterior
of the native β-lg lead to 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 observed effects of hydrophobic subphases on the adsorbed protein
layers provide knowledge, which promotes higher reproducibility in
rheological studies and precise tailoring of interfacial films for
enhanced formation and stability of emulsions.