M. Angela A. Meireles

Determination of the solubility of extracts from vegetable raw material in pressurized CO2: a pseudo-ternary mixture formed by cellulosic structure+solute+solvent

This paper discusses the application of the dynamic method to measure the solubility in pseudo-ternary systems formed by vegetable raw materials (cellulosic structure+solute) and CO2. For aromatic, medicinal, and spice plants, the soluble portion of the solid is formed of essential oils, oleoresins, pigments, and various substances from several other classes of organic compounds. The experimental data were measured in two independent laboratories, using three experimental set-ups, and three vegetable species: clove buds, eucalyptus, and ginger. The solubility for the system clove buds/CO2 varied from 0.220 to 0.277 kg-extract/kg-CO2 for the isotherm of 288.15 K. The ginger extract solubility varied from 2.01×10−3 to 7.20×10−3 kg-extract/kg-CO2 for pressures of 100–300 bar, and temperatures of 298.15–313.15 K. The eucalyptus solubility for the isobar of 66.7 bar varied from 3.95×10−3 to 4.07×10−3 kg-extract/kg-CO2.

Modeling the supercritical fluid extraction of black pepper (Piper nigrum L.) essential oil

Abstract The fixed bed extraction of black pepper essential oil using supercritical carbon dioxide was modeled by the extended Lacks plug flow model developed by Sovova (Sovovas model). The experimental data were obtained for extractions conducted at 30, 40 and 50 ° C , and 150, 200, and 300 bar, for two different types of ground black pepper (batches 1 and 2). The model parameters were evaluated from the experimental data. The fluid-phase mass transfer coefficient was obtained from the constant extraction rate (CER) period using a logarithmical solute mass ratio difference. The Sovovas model was able to describe the experimental data quite well. The best value for the extraction parameter, which relates the resistances of solid-phase mass transfer to fluid-phase mass transfer, was 0.12 and 0.25 for batches 1 and 2, respectively. The experimental data were well represented by the model for the mass ratio of solute present in ruptured cell to the initial mass ratio of solute equal to 65% and 38% for batches 1 and 2, respectively.

Supercritical Fluid Extraction From Stevia Rebaudiana Bertoni Using Co2 And Co2 + Water: Extraction Kinetics And Identification Of Extracted Components

Stevia rebaudiana Bertoni contains glycosides, which are insoluble in carbon dioxide and soluble in mixtures of carbon dioxide and a polar solvent. The purpose of this work was to study the supercritical fluid extraction of these glycosides from stevia leaves using a two-step process: (i) CO2 extraction at 200 bar and 30 °C, and (ii) CO2+water extraction. The chemical compositions of the extracts were analyzed by GC-FID, GC-MS, TLC and HPLC. The overall extraction curves for the system stevia+CO2 had the typical shape and were successfully described by the Sovova’s model. Approximately 72% of the CO2-soluble compounds were recovered and the major compound was austroinulin. The system stevia+CO2+water behaved as expected at 10 and 16 °C and 120 and 250 bar but its behavior was unusual at 30 °C and 250 bar. The process removed approximately 50% of the original stevioside and about 72% of the rebaudioside A.

Modeling the extraction of carotene and lipids from pressed palm oil (Elaes guineensis) fibers using supercritical CO2

Abstract In this work a mathematical model to represent the kinetics of extraction of carotene and lipids from pressed palm oil ( Elaes guineensis ) fibers (PPOF) using supercritical CO 2 is presented. The mass balance equation for the supercritical phase was solved analytically considering a pseudo steady-state. Specifically, the flux at the solid/fluid interface was initially considered constant and afterwards corrected using the dynamic behavior of the extract composition. Experimental data to test the model were obtained at pressures of 250 and 300 bar, temperatures of 45 and 55°C, and solvent flow rates of 1.2–2.0 g/min. The model represented well the experimental data at 45°C as well as the literature data obtained at 250 bar, 55°C and solvent flow rates of 18.9 g/min.

Fundamentals of Microwave Extraction

Microwave-assisted extraction (MAE) is a process that removes solutes from a solid matrix into a solvent. Phenomena such as electromagnetic transfer, heat transfer, mass transfer, and momentum transfer make the process complex. For developing process engineering, the characteristics of heat and mass transfer are extremely significant. Accurate and controlled heat is possible because of the capacity of microwave radiation to penetrate and combine with a substrate. Therefore, the microwave procedure can be designed to transport electromagnetic energy with specific power to the location of the compounds of interest in the substrate. The energy-saving factors and short processing times lead to a reduction in manufacturing costs, and improvement of product uniformity and yields, resulting in products with high quality compared with other extraction techniques. This chapter provides a general review of heat and mass transfer and gives a brief discussion on the factors influencing the extraction efficiency of MAE. The performance of MAE is also compared to other classical methods, thus explaining the advantages of MAE technology as applied to plant extraction research.

Extraction of Clove and Vetiver Oils with Supercritical Carbon Dioxide: Modeling and Simulation

The kinetics of supercritical fluid extraction (SFE) of clove and vetiver oils using carbon dioxide as solvent was studied, in order to establish an efficient method to predict extraction curves on large scale. The mass transfer model of Sovova was used to adjust the experimental SFE data, which were obtained at 100 bar and 35 °C for clove and 200 bar and 40 °C for vetiver, using extraction columns of different geometry and solvent flow rates. Some other process parame- ters, such as bed density and porosity, solvent to feed ratio and solvent velocity were kept constant from one experiment to another, in order to verify if the mass transfer coefficients adjusted by the model varied. The results show that the model of Sovova was able to predict an overall extraction curve for clove from data obtained with twenty times less raw material, since the mass transfer coefficients remained the same and the predicted curves were similar to the observed ones. For vetiver, the simulation was not as effective, probably due to the effects of transport properties on the process.

Improving phase equilibrium calculation with the Peng–Robinson EOS for fats and oils related compounds/supercritical CO2 systems

Abstract Several predictive methods for normal boiling point, critical temperature, critical pressure, and acentric factor, applied to fatty acids and fatty acid esters of high molecular weight were evaluated. The properties estimated by the selected methods were used to analyze the ability of the Peng–Robinson equation of state (EOS) to predict the vapor–liquid equilibria of binary and ternary systems of fats and oils related compounds with CO 2 . Van der Waals mixing rules with the combining rules proposed by Kwak and Mansoori and Park et al. were used. For fatty acids, the method of Constantinou and Gani was selected for the prediction of the critical temperature and that of Somayajulu for the prediction of the critical pressure when experimental boiling temperatures were available. In the absence of experimental data, the method of Constantinou and Gani was selected for the prediction of critical and boiling temperatures, as well as for the critical pressure. For fatty acid esters, the method of Joback and Reid was chosen for the prediction of the critical and boiling temperatures, and that of Constantinou and Gani was selected for the prediction of the critical pressure. The indirect method of Tu was preferred for the prediction of the acentric factors of high molecular weight fatty acids. The correlation of Vetere was chosen for the prediction of the acentric factors of low molecular weight fatty acid esters, and the indirect method of Tu was selected for the prediction of the acentric factors for the methyl ester family. The results for the phase equilibria suggest that the Peng–Robinson equation, with the quadratic mixing rules for the three combining rules tested, is capable of predicting vapor–liquid equilibrium with quality comparable to the results obtained with the mixing rules for more complex models like MHV1 and LCVM.

Phytochemical characterization of essential oil from Ocimum selloi

Ocimum selloi Benth, a native plant of Brazil, has medicinal uses as anti-diarrheic, antispasmodic and anti-inflammatory product. The yield of essential oils of the inflorescences, containing flowers and seeds, was 0.6%, and the yield of leaves, collected in two different seasons, was 0.25% (June 2000) and 0.20% (January 2001), respectively. The essential oils of the inflorescences and leaves presented as major constituents trans-anethol (41.34%, 45.42%, 58.59%) and methyl chavicol (27.10%, 24.14%, 29.96%).

Extraction of the soluble material from the shells of the bacuri fruit (Platonia insignis Mart) with pressurized CO2 and other solvents

The extraction of soluble material from bacuri shells has been studied. The effects of pressure, temperature, particle size, static period and flow time were investigated for extraction with liquid carbon dioxide (LCO2). The yield and the composition of the extracts obtained with LCO2 were compared with those for extracts obtained with other techniques, such as LCO2 plus ethanol (LCO2-EtOH), supercritical CO2 (SCO2), steam distillation (SD), cold ethanol (C-EtOH), and Soxhlet extraction with ethanol (EtOH-So). The LCO2 and LCO2-EtOH extractions were performed at pressures of 63–70 bar, and temperatures of 16–21°C. The constituents isolated from the bacuri shell extracts were predominantly free fatty acids: palmitic, oleic, linoleic, α-linolenic, and stearic acids. In addition to these fatty acids, the LCO2-EtOH extracts contained caprylic and myristic acids, alcohols (linalool and 3,7-dimethyl oct-1-en-3,7-diol), and the phenol ether eugenol. The SCO2 extraction was performed at 200 bar and 50°C. The SCO2 extract had a composition similar to the LCO2 extract, but the α-linolenic acid was not present, although hydrocarbons such as β-bisabolene, and alcohols such as 3,7-dimethyl-1-octen-3,7-diol, linalool, and α-terpineol were identified. In the extract obtained by SD, only hydrocarbons (methyl benzene and 2-methyl heptane), alcohols (linalool and α-terpineol), and oxides (cis-linalool oxide and trans-linalool oxide) were identified. In the C-EtOH and EtOH-So extracts only trimethyl citrate was identified.

Carotenoid Pigments Encapsulation: Fundamentals, Techniques and Recent Trends

Supercritical fluids have become an attractive alternative due to environmentally friendly solvents. The meth- ods that use supercritical fluids can be conveniently used for various applications such as extraction, reactions, particle formation and encapsulation. For encapsulation purposes, the processing conditions given by supercritical technology have important advantages over other methods that include harsh treatments with regard to pH, temperature, light, the use of organic solvents, etc. Unstable functional pigments such as carotenoids extracted from natural sources have been en- capsulated to overcome instability problem. Thus, the most used techniques applicable to this intention are described and discussed in this review as well the recent advances and recent trends in this topic that involves the use of supercritical fluids.