Thermodynamic and dynamic characteristics of monoglyceride monolayers penetrated by beta-casein.

In this work, we have analyzed the dynamics of the penetration of beta-casein into monoglyceride monolayers (monopalmitin and monoolein) and the structural, dilatational, and topographical characteristics of mixed films formed by monoglyceride penetrated by beta-casein. Different complementary experimental techniques [dynamic tensiometry, surface film balance, Brewster angle microscopy (BAM), and surface dilatational rheology] have been used, maintaining the temperature constant at 20 degrees C and the pH at 7. The surface pressure of the monoglyceride monolayer at the beginning of the penetration process (at pi(i)MP and pi(i)MO for monopalmitin and monoolein, respectively) was the variable studied. beta-Casein can penetrate into a spread monoglyceride monolayer at every surface pressure. The penetration of beta-casein into the monoglyceride monolayer with a more condensed structure, at the collapse point of the monoglyceride, is a complex process that is facilitated by monoglyceride molecular loss by collapse and/or desorption. However, the structural, topographical, and dilatational characteristics of the monoglyceride penetrated by beta-casein mixed monolayers are essentially dominated by the presence of the monoglyceride (either monopalmitin or monoolein) in the mixed film.