jf5008715_si_001.pdf (249.72 kB)
Study of Oxygen Transfer across Milk Proteins at an Air–Water Interface with Scanning Electrochemical Microscopy
journal contribution
posted on 2014-03-12, 00:00 authored by Outi Toikkanen, Maija Lähteenmäki, Timo Moisio, Pirkko Forssell, Riitta Partanen, Lasse MurtomäkiScanning electrochemical microscopy
(SECM) combined with a Langmuir
trough was used for studying oxygen transfer across protein films
at an air–water interface. The method allows the comparison
of the oxygen permeability of different emulsifiers without any concerns
of interference of atmospheric oxygen. Two milk proteins, β-lactoglobulin
and β-casein, were compared, and the permeabilities obtained
were for β-casein PD ≈ 2.2 × 10–7 cm2/s and for β-lactoglobulin PD ≈ 0.6 × 10–7 cm2/s, which correspond to the lowest limit of the diffusion coefficients
and are 2 orders of magnitude lower than the diffusion coefficient
of oxygen in water, yet several orders of magnitude higher than previously
reported for milk protein films. The method allows characterization
of the oxygen barrier properties of liquid interfacial films, which
is of crucial importance for understanding the role of the interface
in the inhibition of oxygen transport and developing modified interfaces
with higher oxygen blocking efficacy.