Microspheres of alginate and chitosan were prepared according
to the method of Han, Guenier, Salmieri, and Lacroix (2008). The
microcapsule core solution was prepared by dissolving sodium
alginate (0.02 g/mL) in solution of 10% b-carotene (0.005 g/mL) and
deionized water. Microcapsules were formed by extruding the core
solution in 30 mL syringes through a 22 gauge needle into a calcium
chloride solution (0.1 g/mL) from a height of 5 cmat rate of 30 mL/h
using a Harvard Apparatus Dual Syringe pump (Holliston, MA),
followed by a hardening time of 30 min. For coating with chitosan,
the beads were vacuum filtered using Whatman 42 Ashless filter
paper, rinsed with deionized water, and added to a solution of
chitosan (0.005 g/mL) and glacial acetic acid (diluted with deionized
water to a final concentration of 0.01 mL glacial acetic acid/mL
solution) and gently stirred for 1 h, after which they were transferred
to Whatman 42 Ashless filter paper to dry overnight. Due to
the insolubility of b-carotene in alginate solutions and to achieve a
homogenous solution, water-dispersible b-carotene was used.