Impact of Prosopis alba exudate gum on sorption properties and physical stability of fish oil alginate beads prepared by ionic gelation

This study was conducted to evaluate the effect of Prosopis alba exudate gum (G) as encapsulating matrix component on water-solid interactions, physical state, oxidative damage and appearance properties of alginate-chitosan encapsulates containing fish oil. With this purpose, water sorption isotherms were obtained at 25 degrees C. G increased the hygroscopicity of encapsulates, showing a higher monolayer water content (7.87 +/- 0.47% db.) than control (1.07 +/- 0.04% db.). G introduction reduced the plasticizing effect of water, increasing the a(w) range (a(w) < 0.45) at which samples were in amorphous state and providing the highest protection against lipid oxidation. Appearance properties (chromatic and optical) were affected by hydration and were better maintained in samples containing G at a(w) > 0.52. These results allow considering Prosopis alba exudate gum, as a novel excipient to protect fish oil encapsulated in low moisture polyelectrolyte systems, with the added benefits of employing an undervalued natural resource.