Monoglycerides and -Lactoglobulin Adsorbed Films at the Air-Water Interface. Structure, Microscopic Imaging, and Shea
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- 作者：Marta Cejudo Ferná ; ndez ; Cecilio Carrera Sá ; nchez ; Ma. Rosario Rodrí ; guez Niñ ; o ; Juan M. Rodrí ; guez Patino
- 刊名：Langmuir
- 出版年：2007
- 出版时间：June 19, 2007
- 年：2007
- 卷：23
- 期：13
- 页码：7178 - 7188
- 全文大小：820K
- 年卷期：v.23,no.13(June 19, 2007)
- ISSN：1520-5827
文摘
In this work we have analyzed the structural, topographical, and shear characteristics of mixed monolayers formedby adsorbed 
BORDER=0 ALIGN="middle">-lactoglobulin (-lg) and spread monoglyceride (monopalmitin or monoolein) on a previously adsorbedprotein film. Measurements of the surface pressure (
)-area (A) isotherm, Brewster angle microscopy (BAM), andsurface shear characteristics were obtained at 20 
C and at pH 7 in a modified Wilhelmy-type film balance. The -Aisotherm and BAM images deduced for adsorbed -lactoglobulin-monoglyceride mixed films at lower than theequilibrium surface pressure of -lactoglobulin (
) indicate that -lactoglobulin and monoglyceride coexist at theinterface. However, the interactions between protein and monoglyceride are somewhat weak. At higher surface pressures(at 
) a protein displacement by the monoglyceride from the interface takes place. The surface shear viscosity(
s) of mixed films is very sensitive to protein-monoglyceride interactions and displacement as a function of monolayercomposition (protein/monoglyceride fraction) and surface pressure. Shear can induce change in the morphology ofmonoglyceride and -lactoglobulin domains, on the one hand, and segregation between domains of the film-formingcomponents on the other hand. In addition, the displacement of -lactoglobulin by the monoglycerides is facilitatedunder shear conditions.
BORDER=0 ALIGN="middle">-lactoglobulin (-lg) and spread monoglyceride (monopalmitin or monoolein) on a previously adsorbedprotein film. Measurements of the surface pressure ()-area (A) isotherm, Brewster angle microscopy (BAM), andsurface shear characteristics were obtained at 20 C and at pH 7 in a modified Wilhelmy-type film balance. The -Aisotherm and BAM images deduced for adsorbed -lactoglobulin-monoglyceride mixed films at lower than theequilibrium surface pressure of -lactoglobulin () indicate that -lactoglobulin and monoglyceride coexist at theinterface. However, the interactions between protein and monoglyceride are somewhat weak. At higher surface pressures(at ) a protein displacement by the monoglyceride from the interface takes place. The surface shear viscosity(s) of mixed films is very sensitive to protein-monoglyceride interactions and displacement as a function of monolayercomposition (protein/monoglyceride fraction) and surface pressure. Shear can induce change in the morphology ofmonoglyceride and -lactoglobulin domains, on the one hand, and segregation between domains of the film-formingcomponents on the other hand. In addition, the displacement of -lactoglobulin by the monoglycerides is facilitatedunder shear conditions.