Monoglycerides and -Lactoglobulin Adsorbed Films at the Air-Water Interface. Structure, Microscopic Imaging, and Shea

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• 作者：Marta Cejudo Fern&aacute ; ndez ; Cecilio Carrera S&aacute ; 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 mages/gifchars/beta2.gif" BORDER=0 ALIGN="middle">-lactoglobulin (mages/gifchars/beta2.gif" BORDER=0 ALIGN="middle">-lg) and spread monoglyceride (monopalmitin or monoolein) on a previously adsorbedprotein film. Measurements of the surface pressure (mages/gifchars/pi.gif" BORDER=0 >)-area (A) isotherm, Brewster angle microscopy (BAM), andsurface shear characteristics were obtained at 20 mages/entities/deg.gif">C and at pH 7 in a modified Wilhelmy-type film balance. The mages/gifchars/pi.gif" BORDER=0 >-Aisotherm and BAM images deduced for adsorbed mages/gifchars/beta2.gif" BORDER=0 ALIGN="middle">-lactoglobulin-monoglyceride mixed films at mages/gifchars/pi.gif" BORDER=0 > lower than theequilibrium surface pressure of mages/gifchars/beta2.gif" BORDER=0 ALIGN="middle">-lactoglobulin () indicate that mages/gifchars/beta2.gif" BORDER=0 ALIGN="middle">-lactoglobulin and monoglyceride coexist at theinterface. However, the interactions between protein and monoglyceride are somewhat weak. At higher surface pressures(at mages/gifchars/pi.gif" BORDER=0 > mages/entities/ge.gif"> ) a protein displacement by the monoglyceride from the interface takes place. The surface shear viscosity(mages/gifchars/eta.gif" BORDER=0 >_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 mages/gifchars/beta2.gif" BORDER=0 ALIGN="middle">-lactoglobulin domains, on the one hand, and segregation between domains of the film-formingcomponents on the other hand. In addition, the displacement of mages/gifchars/beta2.gif" BORDER=0 ALIGN="middle">-lactoglobulin by the monoglycerides is facilitatedunder shear conditions.