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978-3-8439-0931-0, Reihe Lebensmitteltechnologie
Encapsulation-related characterisation and applications of thermal whey protein hydrogels
113 Seiten, Dissertation Technische Universität München (2013), Softcover, A5
The technology of encapsulation is applied for stabilisation and controlled release of active compounds and plays an important role in the food sector and in life sciences. Among the wide range of encapsulation systems, hydrogels are interesting encapsulation matrices. Hydrogels are three-dimensional networks consisting of cross-linked polymers which have the ability to imbibe large amounts of water and encapsulate therein dissolved or dispersed compounds. Among biopolymers, whey proteins are well known for their good gelling properties and have been applied as biodegradable, food grade encapsulation matrices.
However, despite their successful application for encapsulation, the knowledge about encapsulation-related properties of whey protein hydrogels is incomplete. A systematic study, bringing into connection hydrogel structure, charge, swelling and mesh size as the main encapsulation-related determinants has not yet been established. Thus the first objective of the present thesis was to fill this gap by characterising the thermal whey protein hydrogels in terms of their pH-dependent swelling kinetics, swelling degree, hydrogel charge and mesh size. It was found that the pH during gelation has a strong impact not only on the resulting network structure but also on the pH-dependent hydrogel charge. These novel insights are relevant for a better understanding of existing whey protein hydrogel-based encapsulation systems. At the same time, the findings served as the empirical basis for the exploration of novel encapsulation applications as the second objective of the present study. In this connection, the hydrogels were succesfully applied for the microencapsulation of a new group of core material (antioxidative plant phenolics) and an innovative processing technique (supercritical drying). It could be shown that for the encapsulation of phenolics whey protein hydrogel matrices can be regarded as a reasonable alternative to the so far solely applied polysaccharides. Moreover, novel protein-aerogels with high inner surface area and drug loading capacity were prepared in collaboration with TU Hamburg-Harburg by an innovative drying procedure using supercritical carbon dioxide. In conclusion, novel knowledge about the structure and encapsulation-related applications of whey protein hydrogels could be gained within the thesis. This is of great relevance for a better understanding of whey protein hydrogel properties and for protein-based hydrogels in general.