Characterization of alginate beads with encapsulated cocoa extract to prepare functional food: Comparison of two gelation mechanisms

In this study we compared two gelation mechanisms for the preparation of alginate beads with encapsulated cocoa extract. We used the extrusion method to induce the external gelation [EG] or internal gelation [IG]. Beads with different cocoa and calcium concentrations were prepared by either gelation mechanism. Size, morphology and texture analysis showed clear differences in the structure of the beads. Those prepared by IG showed a more homogeneous and compact internal structure. Textural studies showed that EG beads were harder due to the more rigid shell formed when the calcium migrated from the exterior of the droplets. The cohesiveness also confirmed a significant difference between the strength of the internal structure of the two beads, in agreement with the morphology observed. At higher calcium concentrations, hardness increased and the diameter of the beads decreased in both cases. The release of polyphenols fitted the Peppas-Sahlin model, and release was delayed at higher calcium concentration, especially for the IG beads. (C) 2015 Elsevier Ltd. All rights reserved.