Supercritical CO2 extraction of sweet and hot paprika oleoresin and other fractions

摘要

Paprika extraction by supercritical CO2 (ESCO2) depends on sample pretreatment (milling, pelletization), the static or dynamic conditions of the pressure, temperature, extraction time, solvent flow and density, the steps of the extractions, or the use of cosolvents. The best conditions according to the literature are prepelletizing samples and extracting at 40 °C in two steps: 13,8-15 MPa for aroma volatiles and β-carotene, followed by 40 MPa for other carotenoids (capsorubin, capsanthine, zeaxanthine, and β-cryptoxanthine). In general, supercritical CO2 extract better the capsaicinoids and tocopherols than the red xanthophylls. To extract capsaicinoids, 32-40 MPa y 40-55 °C have been used, and for chlorophyll pigments in some cultivars and stages of maturity 36 MPa and 45 °C. For tocopherols, 20 MPa and 55 °C or the above conditions have been advised. Depending on the raw paprika composition and the optimum conditions used for the extraction, the yields are variable: 5,2-17,4% (total), 2-3% carotenoids, 0,7-8,6% capsaicinoids in pungent oleoresin, and 370-400 μg tocopherols · g~(-1) oleoresin (mainly the a-tocopherol isomer). The recovery of the compounds of interest by fractionation and optimization of the raw material and extraction process is 90-100%. Ethanol, water and acetic acid are used as cosolvents to extract capsaicinoids, and for β-carotene the 2,2-dimethoxypropane or ESCO2 plus adsorption in silica gel. The ESCO2 allows extracting an oleoresin free from paprika contaminants. The main hazards and critical control point are derived from the high pressure of the CO2, the homogeneity of the solute distribution depending on the previous pretreatments, and the variability of the results in pigment composition compared with that obtained by means of conventional extraction, as well as the difficult to reproduce laboratory results to an industrial scale. The innovations in paprika ESCO2 extract are the aromatized extracts, colorants or deodorized extracts, capsaicinoids extract for food or other uses, as well as oleoresins enriched in zeaxanthines that it is possible to obtain.