Ekstrakcija Mate (Ilex paraguariensis) ugljendioskidom pod pritiskom

Abstract

<p>Within this thesis extraction of Mate tea leaves was performed by ethanol-water mixture, supercritical carbon dioxide and ethanol-water mixture with liquid carbon dioxide as cosolvent. Highest extraction yield was found in Mate extract obtained by the extraction using ethanol-water mixture (40 percents, m/m) with liquid carbon dioxide as co-solvent (100 bar) which can be explained by increased polarity and dissolving power of liquid carbon dioxide in the presence of polar solvents. Effect of the drug particle size on the extraction yield was evaluated for three different particle sizes (d1=0.50 mm, d2=0.33 mm and d3=0.24 mm) for supercritical extraction using pressure of 300 bar, on a temperature of 40şC during 3.5 hours. Highest value was obtained for plant material with the lowest particle size (2.23 percents, m/m) which is understandable because it has the biggest number of destroyed cells from which mass transfer is performed by convection and total surface of plant material is increased so better contact with the solvent is achieved. Coefficients of fast (b) and slow (k) extraction were determined as the measure of kinetic behavior of extraction. Values b and k were increasing from 0.110 to 0.201, and 0.069 to 0.117 for k, which confirmed the dominant role of mass transfer by convection. In this thesis rapid and reliable High-perfformance liquid chromatography (HPLC) methods for determination of methylxanthines (caffeine, theophylline and theobromine) and chlorogenic acid (5-O-caffeoylquinic acid) in Mate tea extracts were developed and validated. Methods showed good selectivity, accuracy, repeatability and robustness. Best results for chlorogenic acid content, total phenolic and flavonoid content and antioxidant activity were achieved in Mate extracts obtained by ethanolwater mixture (40 percents,m/m) with liquid carbon dioxide as co-solvent (100 bar) extraction due to usage of the most polar solvent (5-CQA: 1.66 percents, m/m; total phenolic content: 12.32 percents, m/m; total flavonoid content: 11.50 percents, IC50=0.0034 mg/ml). At the end of this dissertation the modeling of Mate tea leaves extraction was carried out using the model equation of Naik and associates and the modified model equation of Reverchon and Sesti Osseo. Experimental results of methylxanthines extraction from Mate tea leaves were not well fitted for model equation of Naik and associates because it was developed for liquid carbon dioxide and fitted well for modified model equation of Reverchon and Sesti Osseo.</p>