Calcium-alginate coated, whey protein-based microspheres: preparation, some properties and opportunities

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Abstract
An ‘all aqueous’ encapsulation process followed by a heat treatment was used to prepare calcium-alginate-coated, whey protein-based, water insoluble microspheres containing micronized calcium carbonate as a model core. Results obtained with this process were compared to those obtained with a similar process in which chemical cross-linking was utilized. At an initial core load of 25 or 50% (w/w), core retention ranged from 84.2–95.12% and was not significantly affected by the initial core load or by the cross-linking method. Regardless of the cross-linking method, protein retention during the process was high and ranged from 78.2–87.5%. Outer topography of the microspheres was not influenced by the cross-linking method, however, at a given composition, the inner structure of heat treated microspheres differed from that obtained with chemically-cross-linked microspheres. Swelling properties of denovo microspheres were affected by pH. Results indicated that the micronized calcium carbonate could be used as a porogenic core. Removal of the core, by an acid treatment, allowed preparing microporous delivery devices. In addition to offer opportunities for encapsulation and delivery of crystalline core, the investigated process can provide means to prepare ‘ghost’ microporous delivery systems that can, in potential, be loaded, following their preparation, with sensitive core materials at conditions that favour the stability and functionality of this core.