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Enrichment of Supercritical Extracts in beta-Sitosterol by Fractionation Process
Rochová, Kristina ; Sovová, Helena ; Sajfrtová, Marie ; Bártlová, Milena
The aim of this contribution was to use the extraction with supercritical CO2 coupled with fractionation of extract for preparation of extracts rich in beta-sitosterol. Phytosterols have been proved to lower serum cholesterol levels in humans and to have other benefit for human health. Supercritical extraction is a green method to separate such compounds from plants. Sea buckthorn seeds and sunflower seeds were extracted and a mathematical model was applied to determine separation factor of beta-sitosterol as minor component of extract. According to the obtained results, conditions of fractionation were set up. The most important enrichment of a part of extract from seeds with beta-sitosterol was achieved with fractionation in two separators (first separator kept at 15MPa and 50°C) and subsequent fractionation in time at the output of the second separator.
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Enzymatic Reactions in Supercritical CO2
Rochová, Kristina ; Sovová, Helena ; Zarevúcka, Marie
Enzymatic hydrolysis of black current seed oil was carried out in supercritical CO2 (sc-CO2), in continuous flow reactor packed with immobilized enzyme Lipozyme. Black currant seed (Ribes nigrum L.) is rich in alfa- and gama-linolenic acids, bound in triacylglycerols, which have different dietetic effect. Selective hydrolysis allows preparation of fractions with different ratio of the two acids. Effect of reaction conditions (T=30–40°C, P=10-28 MPa) on reaction kinetics, composition of reaction mixture, selectivity and stability of enzyme. Results showed good stability of Lipozyme in sc-CO2. Alfa-Linolenic acid was unbound preferably due to enzyme stereospecificity. Combination of supercritical extraction with enzymatic reaction of extracted oil and subsequent fractionation of reaction mixture in two separators was tested in order to separate desired compounds. Further, stability of several enzymes prepared in our laboratory was tested in sc-CO2.
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Extrakty z rostlin jako směsi a jejich předběžné dělení superkritickým CO2
Sovová, Helena ; Sajfrtová, Marie ; Rochová, Kristina
This work concerns supercritical extraction from plants, a semi-continuous process where solutes are extracted from a fixed bed of plant particles to a stream of supercritical CO2. Though the efficiency of control of extract composition in this one-equilibrium-stage process is lower than in the counter-current column, the composition of extract is affected substantially by extraction conditions. Further equilibrium stages are represented by the following separation of extract from solute in two or more separators adjusted to different pressures and temperatures, where the least soluble components precipitate first.
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Charakter proudění v náplňovém superkritickém extraktoru
Rochová, Kristina ; Sovová, Helena
This contribution provides a brief review on the effect of flow direction on SFE and reports our first experiments on axial dispersion measured in the course of extraction; this topic has not been sufficiently discussed in the literature yet. The flow pattern was examined by means of response to tracer injection and the results were expressed in the form of dimensionless variance S2 T,0. Tetracosane deposited on glass beads was extracted and presence of natural convection was observed when the flow was switched from downflow to upflow mode.
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Supercritical Extraction and Fractionation of Sea Buckthorn Oil: Beta-Sitosterol Selectivity to Oil
Rochová, Kristina ; Sovová, Helena
Sea buckthorn (Hippophae rhamnoides L.) contains large amounts of compounds important in the human diet and used in medicine, among others phytosterols, whose anticancer, anti-inflammatory and antibacterial effects have been proved. Phytosterols, particularly beta-sitosterol, occur in sea buckthorn oil. The oil was extracted from ground seeds with supercritical carbon dioxide at the temperatures 40 and 60 oC and pressures 15-28 MPa. Using HPLC analysis for beta-sitosterol, its selectivity to the oil was evaluated. The results enable us to increase the concentration of beta-sitosterol in the extract.
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