Production of Β-carotene nanosuspensions using supercritical CO₂ and improvement of its efficiency by Z-isomerization pre-treatment

The effects of Z-isomer content of β-carotene on the dispersion efficiency by ultrasound treatment using supercritical CO₂ (SC-CO₂) as an organic phase and the characteristics and storage stability of the obtained suspensions were investigated. β-Carotene containing a large amount of Z-isomer (79.1% of total β-carotene) was prepared by a thermal Z-isomerization and filtering technique from (all-E)-β-carotene. When Z-isomer-rich β-carotene was used as the raw material, the encapsulated β-carotene content was remarkably increased compared to when using (all-E)-β-carotene, e.g., the encapsulated β-carotene content was 21.2 times higher after the 60-min ultrasound treatment at 45 kHz. Furthermore, the Z-isomerization pre-treatment resulted in a reduction of particle size in the suspensions. The mean particle size when (all-E)-β-carotene was used was approximately 700 nm and that when the Z-isomers were used was approximately 100 nm. On the other hand, the suspension obtained from Z-isomer-rich β-carotene had lower storage stability than the all-E-isomer.