Jmr. Patino et al., Adsorption of whey protein isolate at the oil-water interface as a function of processing conditions: A rheokinetic study, J AGR FOOD, 47(6), 1999, pp. 2241-2248
In this paper we present surface dynamic properties (interfacial tension an
d surface dilational properties) of a whey protein isolate with a high cont
ent of beta-lactoglobulin (WPI) adsorbed on the oil-water interface as a fu
nction of adsorption time. The experiments were performed at constant tempe
rature (20 degrees C), pH (5), and ionic strength (0.05 M). The surface rhe
ological parameters and the interfacial tension were measured as a function
of WPI concentration (ranging from 1 x 10(-1) to I x 10(-5)% w/w) and diff
erent processing factors (effect of convection and heat treatment). We foun
d that the interfacial pressure, pi, and surface dilational modulus, E, inc
rease and the phase angle, phi, decreases with time, theta, which should be
associated with WPI adsorption. These phenomena have been related to diffu
sion of the protein toward the interface (at short adsorption time) and to
the protein unfolding and/or protein-protein interactions (at long-term ads
orption) as a function of protein concentration in solution and processing
conditions.