Jm. Girardet et al., Viscoelastic properties of oil-water interfaces covered by bovine beta-casein tryptic peptides, J DAIRY SCI, 83(11), 2000, pp. 2410-2421
A combination of proteolysis and dilational rheology has been used to study
the behavior of films of beta -casein (DCN) and of peptides spread at the
oil-water interface. Identification of the peptides produced by trypsin hyd
rolysis of beta -CN in emulsion at 37 degreesC provided information on the
structure of beta -CN adsorbed at the oil-water interface. Good interface p
roperties were observed for beta -CN or its peptides, probably because of t
he amphipathic nature of DCN or a synergistic effect between hydrophilic an
d hydrophobic peptides. Remarkable surface activity was found for the amphi
pathic peptide beta -CN (f114-169). Rheological studies had shown that inte
rface films made with peptide fractions or with beta -CN were elastic rathe
r than viscous. Film made with the purified peptide beta -CN (f114-169) was
merely elastic at the triolein-water interface. A decrease of the viscoela
stic modulus was observed for aging beta -CN film but not for aging peptide
films; The beta -CN decrease was related to the flexibility of its structu
re. When the interface is increased by the dilation of an aqueous droplet p
lunged into oil, beta -CN may expose new polypeptide trains to cover the in
creased interface, unlike peptides with simpler structures.