Supercritical Antisolvent Micronization of Natural Carotene by the SEDS Process through Prefilming Atomization

Abstract

Natural carotene is micronized by the SEDS process through prefilming atomization (SEDS-PA) with the aim of evaluating the efficiency of prefilming atomization, examining the variation of carotene purity induced by the SEDS-PA process and studying the influence of operating variables on the particle size (PS) of the carotene precipitates. The carotene/dichloromethane solution to be atomized is driven through a liquid distributor with spiral slots in the prefilming atomizer as a thin film swirling at 45°. At the exit of the atomizer, the atomizing supercritical CO 2 (SC-CO 2 ) stream impinges on the film at 45°. Through the impingement and the use of swirling, the annular solution film is disintegrated into fine drops, and the mixing of the SC-CO 2 and solution is intensified. Compared to the process in which solution is driven through the inner capillary of the atomizer while SC-CO 2 is driven through its annular passage, the SEDS-PA process can obtain smaller droplets and finer microparticles with a narrower particle size distribution (PSD). After micronization by the SEDS-PA process, the purity of carotene microparticles is increased for unprocessed carotene with purity ranging from 30% to 87%, but it decreased for carotene with purity higher than 87%. The CO 2 flow rate, solution flow rate, solution concentration, and pressure have marked influences on the particle size (PS), and the PSD broadens with increasing PS. Mechanisms that control PS are explained in terms of liquid atomization, agglomeration of particles, volumetric expansion of solution in SC-CO 2 , and nucleation and growth processes of particles. The dependence of the PS on temperature is not clear from all of the experiments performed.

Precipitation of β-carotene microparticles from SEDS technique using supercritical CO2

“…Second, with this technique the solvent is mostly eliminated by long step drying of particles with fresh anti-solvent (Bleich and Muller, 1996;Ruchatz et al, 1997). Therefore, dichloromethane has been used in the precipitation of pure carotenoids (Miguel et al, 2006;He et al, 2006) and in the formation of composite particles and coprecipitation of carotenoids and biopolymers (Martín et al, 2007;Hong et al, 2007;He et al, 2007;Mattea et al, 2008).…”

“…The same technique was also used by Cocero and Ferrero (2002) to recrystallize b-carotene from ethyl acetate and dichloromethane solutions using carbon dioxide as anti-solvent. The Solution-Enhanced Dispersion by supercritical fluids (SEDS) technique was employed by He et al (2006) for the precipitation of natural b-carotene using a pre-filming atomization system. These authors have focused on the efficiency of pre-filming atomization, studying the effect of several parameters on the particle size, size distribution and purity of precipitated carotene.…”

Carotenoid processing with supercritical fluids

“…Most of these research works also studied the effect of different injectors, except for He et al (2006) where only a special prefilming atomization injector was used. A brief description of the results of these works can offer a guide for the selection of the proper parameters for carotenoids precipitation with supercritical fluids.…”

“…Concentration changes did not show any defined trend in the obtained particle size. He et al (2006) used an improved mixing concentric tube with prefilming atomization nozzle to enhance the droplet formation. They studied the effect of all the process variables over the particle size and PSD explaining their results with super saturation and agglomeration analysis.…”

Micronization of the officinal component baicalin by SEDS‐PA process

“…Ephedrine, bixin and natural carotene were successfully micronized by the SEDS through Prefilming Atomization (SEDS-PA) process [20][21][22]. With the recognition of toxicities and side effects of synthetic medicaments and in view of the fact that some diseases cannot be cured by the synthetic medicaments, Chinese herbal medicines are receiving increasing attention.…”