Precipitation of carotenoids with the supercritical antisolvent process

Resumen

Micronization processes based on the use of CO2 as anti solvent are a promising alternative to conventional crystallization processes. With this technology, it is possible to obtain micron- or sub-micron- particles of a wide range of materials, with a controlled particle size distribution. Moreover, the use of CO2 as anti solvent allows to carry out the process with mild operating conditions, and therefore with a lower risk of degradation of sensible materials, and with a reduced use of organic solvents. For these reasons, several micronization processes with CO2 as anti solvent have been proposed in the last years. Carotenoids are natural colorants and antioxidants that suffer degradation under the action of light, oxygen or moderate temperatures. They are frequently used in the food and pharmaceutical industries. For these applications the contamination of the carotenoids with toxic substances must be avoided. Supercritical Antisolvent processes are a very convenient alternative for the precipitation of carotenoids, as they allow to avoid the contamination or degradation of the product. This thesis presents a study of the precipitation of three carotenoids: -carotene, lycopene and lutein with the Supercritical Antisolvent process, as well as of the co-precipitation of these carotenoids with polymers. The precipitation of -carotene is the first application studied in this thesis. Based on previous results with a batch Gas Antisolvent precipitation process, the following operating conditions were selected: pressure 9-10 MPa, temperature 25 - 35ºC, working with solutions of -carotene in dichloromethane with concentrations varying from 400 ppm to 1500 ppm. With these conditions, particles of -carotene with sizes ranging from 1 m to 200 m were produced. The agglomeration of the particles was one of the main problems detected, and it was found that in order to reduce this agglomeration it was necessary to operate with high pressures and high solution flowrates