Incompatibility and Phase Separation in a Bovine Serum Albumin/β-Casein/Water Ternary Film at the Air–Water Interface

✍ Scribed by Tapashi Sengupta; Srinivasan Damodaran

• Publisher: Elsevier Science
• Year: 2000
• Tongue: English
• Weight: 248 KB
• Volume: 229
• Category: Article
• ISSN: 0021-9797
• DOI: 10.1006/jcis.2000.6992

✦ Synopsis

Thermodynamic incompatibility and two-dimensional phase separation in a bovine serum albumin (BSA)/beta-casein/water ternary film at the air-water interface has been studied using an epifluorescence microscopy technique. The incompatibility between BSA and beta-casein at the air-water interface was deduced from deviation of the experimental equilibrium composition of the proteins in the mixed saturated monolayer film from that predicted by the Langmuir-type competitive adsorption model at various bulk concentration ratios. Fluorescence microscopy of the mixed monolayer film showed distinct phase-separated BSA-rich and beta-casein-rich regions coexisting with inhomogeneous mixed regions. BSA always tended to be the dispersed phase and beta-casein the continuous phase. It is suggested that because the free energy at the "interfaces" between the phase-separated regions is generally higher than at other regions of the film, they may act as zones of instability in protein-stabilized foams and possibly emulsions. Copyright 2000 Academic Press.