Analysis of beta-casein-monopalmitin mixed films at the air-water interface

The surface pressure (pi)-area (A) isotherms and Brewster angle microscopy (BAM) images of monopalmitin and beta-casein mixed films spread on buffered water at pHs 5 and 7 and at 20 degrees C were determined as a function of the mass fraction of monopalmitin in the mixture (X). The structural charac teristics and morphology of monopalmitin-beta-casein mixed films are depend ent on surface pressure, pH, and monolayer composition. The prevalence of m onopalmitin in the interface increases with the amount of monopalmitin in t he mixture and at higher pi. At the monopalmitin monolayer collapse the mix ed film is practically dominated by the presence of monopalmitin. However, some degree of interactions exist between monopalmitin and beta-casein in t he mixed film, and these interactions are more pronounced as the monolayer is compressed at the highest surface pressures.