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

Abstract The effects of Z -isomer content of β-carotene on the dispersion efficiency by ultrasound treatment using supercritical CO 2 (SC-CO 2 ) 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.