Stability and release of an encapsulated solvent-free lycopene extract in alginate-based beads

- A high lycopene grapefruit extract was obtained by a free solvent process.
- Trehalose and galactomannans were used for alginate-Ca(II) bead preparation.
- Gum particular characteristics have an impact on lycopene content and stability.
- Lower diffusion coefficient was related to higher lycopene content in beads.
- Sugars and biopolymers addition to the beads strongly affects lycopene release.

A free-solvent lycopene extract was obtained from a natural and non-conventional source such as pink grapefruit. Five matrices were evaluated to select the matrix for lycopene extraction, choosing freeze-dried pulp based on the high content and conservation of all-trans lycopene. The extraction was dependent on both partial preservation of the fruit cellular/tissular structure and water content. The extract was then encapsulated in alginate beads with the addition of sugars and galactomannans. The influence of beads composition was studied on stability towards isomerization, transport properties and release of lycopene. Alginate beads and those supplemented with trehalose and vinal gum were the ones that best preserved lycopene content and minimized isomerization changes. Transport properties measured by LF-NMR showed that lower diffusion coefficients could be related to higher lycopene content in alginate-trehalose beads. Lycopene release was strongly influenced by composition. Then, it is possible to design formulations with different release rates for particular applications.