Bioactive components encapsulated in gel particles offer a means to deliver these components in a time release fashion to improve health through daily diet. The objective of this work was to evaluate the physical/mechanical properties of a release system consisting of whey protein/alginate gel beads in a model beverage. Riboflavin, vitamin B-2, was incorporated in the gel beads as a model bioactive compound. Gel beads were formed both with and without riboflavin and then added to a xanthan/sucrose suspending medium. Both the beads and the polymer solutions from which they were formed were characterized by standard rheological methods. An absorbance method was used to monitor riboflavin release over time. NMR and MRI (magnetic resonance imaging) methods characterized bead integrity and the state of protons in the gel beads. The combination of whey protein and alginate formed beads with good integrity and zero order rate kinetics for the release of riboflavin. The release rate of the bioactive component was more rapid that the typical shelf life of a bottled beverage however, the work represents a step toward the design of this type of functional food through characterization of the encapsulation medium. (C) 2013 Elsevier Ltd. All rights reserved.