Fig. 6.

Characterization of different delivery systems: emulsion, microcapsules, GT/Fe II/III coated microcapsules, respectively. A), B), C) fluorescence images of different Vitamin D delivery systems after exposure to the simulated GIT. A), B) and C) present free vitamin D (emulsion), encapsulated Vitamin D (microcapsules), and coated shell encapsulated vitamin D (GT/Fe II/III microcapsules) system, respectively (scale bar is 20 µm); d) electrical characteristics (ζ potential) of three delivery systems under different pH conditions and after exposure to the simulated GIT stages; e) nutrients recovery of three delivery systems determined using HPLC in in-vitro digestion model.