Zeaxanthin nanoencapsulation with Opuntia monacantha mucilage as structuring material: Characterization and stability evaluation under different temperatures

The use of cactus cladode mucilage (Opuntia monacantha) was exploited as a new natural structuring material to zeaxanthin nanoencapsulation. The zeaxanthin nanoparticles (Zea-NP) were characterized regarding particle size distribution, span value, zeta potential, pH, viscosity, color, morphology, thermal properties, encapsulation efficiency and FTIR spectroscopy after preparation. A nanoemulsion (Zea-NE) was developed and evaluated to compare the physicochemical properties and stability with the nanoencapsulated zeaxanthin. The stability of nanoencapsulated and unencapsulated zeaxanthin was evaluated during 28 days of storage at 4, 25 and 40 degrees C regarding particle size, span value, pH, color, and zeaxanthin retention (%). Zea-NP presented a mean diameter of 184 +/- 3.54 nm and homogeneous distribution, zeta potential of -14.8 +/- 0.42 mV and encapsulation efficiency of 96.57%. Zea-NP showed spherical shape, and the thermal analyses indicated that nanoparticles were more stable than nanoemulsion. After 28 days of storage at 25 degrees C and 40 degrees C, the zeaxanthin retention in Zea-NP was higher than in Zea-NE. The obtained results support that cactus cladode mucilage protected zeaxanthin from degradation and have potential to be used as structuring material in nanoencapsulation.