ISBN 9783843919340

978-3-8439-1934-0, Reihe Lebensmitteltechnologie

Anne Karoline Kessler
Physico-chemical characterization of novel casein-surfactant micelles

249 Seiten, Dissertation Universität Hohenheim Stuttgart-Hohenheim (2014), Softcover, A5

Zusammenfassung / Abstract

Micelles are thermodynamically stable assemblies used to encapsulate functional compounds, which, for example, enables to enrich water-based systems with hydrophobic compounds. As micelles have to be suitable for the hydrophobic compound and the field of application, there is a great need in micelles with various functionalities. This thesis is focused on the development of a micellar carrier system composed of caseins, a protein naturally occurring in milk, and a second surfactant. A block copolymer seemed to be suitable as a second surfactant, as caseins also have a block copolymer like structure. To check this hypothesis, αs-casein and the block copolymer PEO13 − PPO30− PEO13 (tradename PE6400) were studied by way of example. In-house fractionated αs-casein and commercially available PEO13− PPO30− PEO13 dispersed in buffered solutions at pH 6.6 were used throughout the whole study. The miscibility with water was determined by turbidity measurements. The formed aggregates were characterized by ζ-potential and fluorescence measurements and their size was studied by dynamic light scattering (DLS). Isothermal titration microcalorimetry (ITC) and evaluation of the measured CMCs allowed an insight in the thermodynamics of micelle formation. αs-Casein, PEO13 − PPO30 − PEO13 and mixtures thereof were miscible with water at certain temperature and concentration ranges. In this one-phase region, mixed micelle formation was observed. The structure of the mixed micelle was assumed to be similar to the necklace and bead model. As the determination of the size was not possible by dynamic light scattering due to interparticle interactions, the size was estimated by molecular geometry considerations. The mixing properties are determined to be antagonistic. The hydrophobic model solute pyrene could be encapsulated showing the functionality of the carrier. The newly developed system seems to be a promising approach for the encapsulation of hydrophobic drugs which should be released in the gastro-intestinal tract, as caseins are digestible. If one thinks on a potential usage in food systems one would need to replace the PEO13− PPO30− PEO13 by a food grade polymer.