Continuous Production of Z-Isomer-Rich β-Carotene Nanosuspensions Utilizing Subcritical Fluid and a Swirl-Type Mixer

Abstract

This study aimed to produce Z-isomer-rich β-carotene nanosuspensions via a continuous production system. β-Carotene with a high Z-isomer ratio was prepared from the all-E-isomer using a continuous-flow reactor under subcritical ethyl acetate conditions. Using this isomerization system, the total Z-isomer ratio increased to approximately 60% after only 30 s. β-Carotene suspensions were continuously produced using a swirl-type mixer. During this dispersion process, the effects of the dispersion conditions (flow rate, temperature, and pressure) and isomer ratio of the β-carotene material were investigated. Finally, the encapsulation efficiency of β-carotene exceeded 80% and Z-isomer-rich β-carotene nanosuspensions (total Z-isomer ratio of approximately 60%, mean particle size of approximately 5 nm) were obtained. The Z-isomer-rich β-carotene nanosuspensions should have greater β-carotene bioavailability and biological activity than the all-E-isomer-rich ones, and they are expected to be utilized as colorants and nutritional agents in the food industry and as sunscreens in the cosmetic industry.

Preparation of Highly Stable Z‐Isomer‐Rich Lycopene Nanodispersions via a Continuous‐Flow System with Selected Emulsifiers

“…[ 21,23 ] The extraction of lycopene isomers from the dispersions was carried out using a mixture of methanol and hexane as described elsewhere. [ 20,29 ]…”

“…The main and subflow channels of the swirl mixer had diameters of 0.8 and 0.5 mm, respectively. To optimize the dispersion of lycopene in the aqueous emulsifier solution, the effects of the ratio of feed flow rates, temperature (40-70 °C), and pressure (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) for Tween 20 as an emulsifier, were examined. The ethyl acetate solution was fed to the main flow channel at 0.5 mL min −1 , and the aqueous solution was fed to the subflow channel at 2.5-10 mL min −1 , that is, the ethyl acetate solution/aqueous solution flow rate ratio varied from 1:5 to 1:20 (v/v).…”

“…The ethyl acetate solution was fed to the main flow channel at 0.5 mL min −1 , and the aqueous solution was fed to the subflow channel at 2.5-10 mL min −1 , that is, the ethyl acetate solution/aqueous solution flow rate ratio varied from 1:5 to 1:20 (v/v). [18][19][20] The obtained lycopene dispersions were collected after they passed the backpressure regulator and immediately ethyl acetate was removed from the solution using a rotary evaporator under reduced pressure at 40 °C to afford Z-isomer-rich lycopene nanodispersions. This emulsification-evaporation technique was traditionally conducted to obtain carotenoid nanodispersions.…”

“…[21,23] The extraction of lycopene isomers from the dispersions was carried out using a mixture of methanol and hexane as described elsewhere. [20,29] Figure 2. Normal-phase HPLC chromatograms of lycopene isomers A) before and B) after thermal isomerization.…”

“…Among the variety of in-line (e.g., Y-shaped, coaxial-nozzle, central-collision, and swirl) mixers developed for liquid-liquid dispersion, we employed a swirl mixer, which is known to afford small particles with a narrow size distribution. [18][19][20] Moreover, we evaluated the effects of dispersion conditions (flow rate, pressure, and temperature), Z-isomer ratio of introduced lycopene, and emulsifier type (polyoxyethylene [20] sorbitan monolaurate [Tween 20], sucrose fatty acid ester [SFAE], and polyglycerol fatty acid ester [PFAE]) on the encapsulated lycopene content (encapsulation efficiency), the total Z-isomer ratio of encapsulated lycopene, and the related particle size distribution. As lycopene Z-isomers relatively easily decompose and/or isomerize into the all-E-isomer during storage), [21,22] their stability needs to be improved to facilitate the practical use of Z-isomer-rich lycopene products.…”