Model salad dressing emulsions of an oil volume fraction of 0.50 were prepared using
two types of lupin seed protein isolate (LSPI) differing in the method applied for
their isolation and their protein composition. The dressing stability against creaming
and droplet coalescence were studied and correlated with data on oil droplet size,
rheological characteristics and the amount of protein adsorption at the droplet surfaces.
Model salad dressing emulsions containing the isolate, mainly composed of lupin globulins,
exhibited higher stability and more pronounced rheological characteristics compared
to those prepared with the isolate enriched in albumins or with the mixture of the
two isolates. The lupin albumins appeared to displace the globulins from the droplet
surfaces, following competitive adsorption from mixtures of the two types of the lupin
isolates. The results are discussed in terms of droplet interaction and rearrangement
as they are influenced by the presence of the adsorbed protein molecules and aggregates
which appear to determine long-term stability of the emulsion systems. (c) 2006 Society
of Chemical Industry.