Encapsulation of a free-solvent extract of lycopene in alginate-Ca(II) beads containing sugars and biopolymers

Abstract

Background: The purpose of the present study was to enhance the stability toward isomerization and control the release of an encapsulated free-solvent extract of lycopene, obtained from a nonconventional natural source, by means of alginate beads containing sugar (trehalose) and biopolymers (chitosan, low methoxyl pectin, and arabic gum). Methods: Lycopene was extracted from freeze-dried pulp of pink grapefruit obtaining a free solvent extract. Lycopene encapsulation was conducted by a double procedure consisting of emulsification and ionotropic gelation in alginate-Ca(II) beads, modified by the addition of sugar and biopolymers. The influence of beads’ composition was studied on lycopene stability and release, as well as molecular mobility and diffusion in the beads. Results and Conclusions: The addition of a second excipient (besides alginate) in the formulation should be carefully conducted, since stability during alginate-Ca(II) bead generation could be even compromised, leading to high lycopene losses. Beads containing trehalose and chitosan were the ones that best preserved the lycopene content and minimized isomerization changes. This could be related to the reduced molecular mobility and lower diffusion coefficient of this system. Lycopene release was severely affected by the composition of the beads, allowing to modulate its release depending on a desired application. Then, a good strategy to obtain high lycopene formulations ready to use or for their incorporation in a subsequent technological process (such as freeze-drying or extrusion) was reported in the present study.