Enhanced production of β-carotene suspensions using supercritical CO₂ via naturally occurring Z-isomerization-accelerating catalyst

β-carotene has high antioxidant activity and its adequate intake can reduce the risk of various diseases. Thus, β-carotene can be utilized as a dietary supplement and valuable natural food colorant. Z-isomerization of β-carotene can reduce the crystallinity of (all-E)-β-carotene and improve the solubility of it in solvents. Preparing nanosuspensions of Z-isomer-rich β-carotene can improve the dispersibility of β-carotene in water and bioavailability of it. In previous work, Z-isomerization and encapsulation process of β-carotene was implemented in two separated steps. In this work, organic catalyst derived from plants was utilized for Z-isomerization of β-carotene. The Z-isomerization and emulsification-evaporation process were conducted simultaneously under supercritical CO₂ assisted by ultrasound. β-carotene suspension produced in this work was characterized by UV-vis, HPLC and DLS. The nanosuspensions rich in Z-isomers of β-carotene has been successfully prepared using allyl isothiocyanate (AITC) as the catalyst for Z-isomerization. When the distributed processing was performed with 50mg, 100 mg AITC, the encapsulation efficiency and Z-isomerization ratio in the suspensions were approximately 6 times and 13 times higher than those of no catalyst. Adding AITC in the emulsification-evaporation process using SC-CO₂ as a Z-isomerization-accelerating catalyst improved not only the Z-isomerization ratio of βcarotene but also the encapsulated β-carotene content in suspensions.