S.A.B. Vieira de Melo

Extraction of caffeine, chlorogenic acids and lipids from green coffee beans using supercritical carbon dioxide and co-solvents

The paper reports on experimental data on the extraction of caffeine, coffee oil and chlorogenic acids from green coffee beans using pure supercritical CO2 and supercritical CO2 modified with ethanol (5% w/w) and isopropyl alcohol (5% w/w) at 50 and 60oC and 15.2 24.8 e 35.2 MPa. In this study extraction kinetics were obtained for all assays i.e. samples were collected at several time intervals for each solvent and mixed solvent. When pure CO2 and CO2-ethanol mixed solvent were used, an increase in pressure resulted in an increase in the amount of oil extracted. When CO2 was modified with isopropyl alcohol, the amount of coffee oil extracted also increased with pressure. Caffeine extraction initially increased and subsequently decreased with pressure. Chlorogenic acids were only extracted when isopropyl alcohol was used as a co-solvent. An increase in extraction temperature resulted in a decrease of caffeine and oil extraction (retrograde condensation) when only CO2 was used as solvent. With the use of co-solvent this retrograde behavior was no longer observed and the increase in temperature resulted in the increase in the extracted amounts of caffeine, coffee oil and chlorogenic acids.

Phase transition and volume expansion in CO2-expanded liquid systems

Phase Transition and Volume Expansion in CO2-Expanded Liquid Systems Felipe G. Denardin, Silvio A. B. Vieira de Melo, Raffaella Mammucari, Neil R. Foster Departamento de Engenharia Quimica, Universidade Federal de Santa Maria, Avenida Roraima 1000, 97105-900, Santa Maria-RS, Brazil Programa de Engenharia Industrial, Escola Politecnica, Universidade Federal da Bahia, Rua Prof. Aristides Novis, 2, Federacao, 40210-630, Salvador-BA, Brazil School of Chemical Enginerring, The University of New South Wales, Sydney, New South Wales 2052, Australia sabvm@ufba.br Tel. +55-71-32839800 Fax +55-71-32839801

Supercritical CO2 extraction of essential oils from Thymus vulgaris

Supercritical CO2 extraction of essential oil from Thymus vulgaris leaves was studied using experimental data recently obtained in the Florys S.p.A. laboratory. Mass transfer coefficients in the supercritical and solid phases from extraction curves at 40°C and 20 MPa were evaluated using a mathematical model based on the local adsorption equilibrium of essential oil on lipid in leaves. The adsorption equilibrium constant was fitted to these experimental data, and internal and external mass transfer resistances were calculated, allowing identification of the mechanism controlling the extraction process.