Kinetics of ascorbic acid transport from alginate beads during in vitro digestion

Abstract

This work aimed at the behaviour of multilayer alginate beads loaded with antioxidants depending on the type of preparation and at characterization of their transport rates under simulated gastrointestinal conditions. Changes in mechanical properties reflected changes in the gel microstructure with the beads becoming stronger in gastric phase (values of Young’s modulus of approx. 4 × 104 Pa) and weaker in intestinal conditions (Young’s modulus of approx. 0.5 × 104 Pa). Investigation of the swelling behaviour showed that all beads shrank in gastric conditions and swelled in intestinal conditions, with multilayer capsules displaying more significant shrinkage and swelling (by 40%). Results on the release of the antioxidant from the capsules suggested that the preparations were able to withstand harsh gastric conditions retaining more than a half of ascorbic acid at the end of gastric phase, and facilitate its transport to the simulated small intestine. A direct relationship between mechanical characteristics of the alginate beads and transport of the bioactive compound was established within the experimental time. It was shown that 90% of the bioactive transport was governed by the nature of the capsules, where their mechanical properties are considered to be a basis of optimal utilization of the controlled delivery