Development of a continuous production system for Z -isomer-rich carotenoid/2-hydroxypropyl-β-cyclodextrin inclusion complexes using a flow reactor and a spray dryer

Recent studies have shown that Z -isomers of carotenoids have greater bioavailability and biological activity than their naturally predominant all- E -isomers; however, carotenoid Z -isomers are chemically unstable and insoluble in water, hindering their practical application. This study aimed to develop a process for producing water-soluble Z -isomer-rich carotenoid inclusion complexes using 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) as a carrier. Continuous production of water-soluble formulations containing Z -isomer-rich carotenoids (> 55%) was successfully achieved utilizing a heated flow reactor and a spray dryer. We found that the introduction of the Z -isomerization process prior to the spray-drying process significantly improved the encapsulation efficiency of carotenoids, possibly due to changes in their physical properties with Z -isomerization. The storage test on the resulting powders showed that the formulation of carotenoid Z -isomers effectively stabilized their Z -structures. The findings of this study are anticipated to make a valuable contribution to the practical application of Z -isomer-rich carotenoid materials with high usability and health benefits.