Danielle Barth

Phase Equilibria Measurements and Modeling of EPA and DHA Ethyl Esters in Supercritical Carbon Dioxide

Abstract A high pressure, variable-volume visual cell was used to perform static measurements of phase equilibria involving carbon dioxide and two different fatty acid ethyl esters: eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) ethyl esters. Six temperatures ranging from 303.15 to 353.15 K were selected. In a second step, our data were compared with predictions obtained by two group contribution based models previously published. Both models are able to predict with quite high accuracy our data whatever the temperature.

Desorption of lemon peel oil by supercritical carbon dioxide: Deterpenation and psoralens elimination

Abstract Citrus peel oils, obtained by cold pressing, contain large quantities of hydrocarbon terpenes and smaller amounts of psoralens. Some of these latter compounds can exhibit phototoxic activity. Desorption of “Eureka” lemon peel oil by supercritical C0 2 from a polar adsorbent was performed to selectively eliminate hydrocarbon terpenes and psoralens by operating at different C0 2 densities. The various fractions obtained were analyzed by GC-MS. Four fractions were characterized: terpenic fraction, deterpenated fraction, waxes, and residue. The deterpenated fraction contained about 76% of oxygenated terpenes. All coumarins and psoralens contained in the starting material were concentrated in the waxes and in the residue. Particular attention was dedicated to ascertaining the elimination of bergapten and oxypeucedanin whose photosensitizing activity is well known.

Rapid identification of some coumarin derivatives in deterpenated citrus peel oil by gas chromatography

Generally on the gas chromatogram of a volatile essential oil, terpenes, oxygenated compounds and sesquiterpenes appear. With temperature programming, it was shown that some non-volatiles are present with the volatiles. They are simple coumarin (2H-1-benzopyran-2-one) derivatives such as citropten (5,7-dimethoxycoumarin) and furocoumarins (psoralen, 7H-furo[3,2-g][1]benzopyran-7-one) such as bergapten (5-methoxypsoralen), some of which are phototoxic. Terpeneless oils are used in perfumes and cosmetics, so it is important to be able to establish rapidly if they contain phototoxic compounds.

ADSORPTION AND DESORPTION OF M-XYLENE FROM SUPERCRITICAL CARBON DIOXIDE ON ACTIVATED CARBON

The equilibrium loadings of m-xylene from supercritical carbon dioxide on activated carbon are reported. The experimental data were obtained by measuring the outlet concentration of m-xylene eluted from a column packed with activated carbon until the effluent reached the input concentration. The Freundlich isotherm expression was found to correlate the experimental data satisfactorily. In a second step, the regeneration by supercritical carbon dioxide of activated carbon loaded with m-xylene was investigated. The experimental data demonstrated that the adsorptive capacities of the regenerated activated carbon for m-xylene after many cycles were close to those of the virgin carbon and remained stable. The effects of temperature, pressure, and flow rate on regeneration efficiency were also studied.

Supercritical CO2 extraction of oil, fatty acids and flavonolignans from milk thistle seeds: Evaluation of their antioxidant and cytotoxic activities in Caco-2 cells

The optimal conditions of supercritical carbon dioxide (SC-CO2) (160-220 bars, 40-80 °C) technology combined with co-solvent (ethanol), to recover oil, flavonolignans (silychristin, silydianin and silybinin) and fatty acids from milk thistle seeds, to be used as food additives and/or nutraceuticals, were studied. Moreover, the antioxidant and cytotoxic activities of the SC-CO2 oil seeds extracts were evaluated in Caco-2 carcinoma cells. Pressure and temperature had a significant effect on oil and flavonolignans recovery, although there was not observed a clear trend. SC-CO2 with co-solvent extraction at 220 bars, 40 °C was the optimum treatment to recover oil (30.8%) and flavonolignans from milk thistle seeds. Moreover, linoleic (47.64-66.70%), and oleic (19.68-24.83%) acids were the predominant fatty acids in the oil extracts recovered from milk thistle under SC-CO2. In addition, SC-CO2 extract showed a high antioxidant activity determined by DPPH and ABTS tests. Cytotoxic activities of silychristin, silydianin and silybinin and the obtained SC-CO2 extract (220 bars, 40 °C) were evaluated against Caco-2 cells. The SC-CO2 extract inhibited the proliferation of Caco-2 cells in a dose-responsive manner and induced the highest percentage of mortality of Caco-2 cells (from 43 to 71% for concentrations from 10 up to 100 μg/ml of SC-CO2 oil seeds).

Response surface methodology applied to Supercritical Fluid Extraction (SFE) of carotenoids from Persimmon (Diospyros kaki L.).

Supercritical carbon dioxide with ethanol as co-solvent was used to extract carotenoids from persimmon fruits (Diospyros kaki L.). Based on a response surface methodology (RSM), a predicting model describing the effects of CO2 temperature, pressure, flow rate, ethanol percentage and extraction time was set up for each of the four carotenoids of interest. The best extraction yields in our experimental domain were found at 300 bars, 60°C, 25% (w/w) ethanol, 3mL/min flow rate and 30min for xanthophylls (all-trans-lutein, all-trans-zeaxanthin and all-trans-β-cryptoxanthin). The yields were 15.46±0.56, 16.81±1.74 and 33.23±2.91μg/g of persimmon powder for all-trans-lutein, all-trans-zeaxanthin and all-trans-β-cryptoxanthin, respectively. As a non-oxygenated carotenoid, all-trans-β-carotene was better extracted using 100 bars, 40°C, 25% (w/w) ethanol, 1mL/min flow rate and 30min extraction time, with an extraction yield of 11.19±0.47μg/g of persimmon powder.

Mandarin and Lime Peel Oil Processing by Supercritical CO2 Desorption: Deterpenation and High Molecular Weight Compounds Elimination

Abstract Desorption of mandarin and lime peel oils from a polar adsorbent was performed by supercritical CO2 to selectively eliminate terpene hydrocarbons and high molecular weight compounds (like paraffins, coumarins, psoralens and polymethoxyflavones) thus improving the oil quality. Peel oil fractionation was obtained starting the desorption process at 40°C temperature and 75 bar pressure and by stepwise increasing pressure to 85 and 100 bar. Three fractions were characterized by GC/MS analysis: terpenic fraction, deterpenated fraction and residue. The content of oxygenated compounds in the deterpenated fraction was 43 times higher than in the crude oil in the case of mandarin and three times higher in the case of lime oil. Coumarins, psoralens, polymethoxyflavones and waxes contained in the starting material were also identified in the mandarin residue fraction.

VOCs isotherms on Day zeolite by static and dynamic methods: Experiments and modelling

Abstract A dynamic method and a static gravimetric method are respectively used to measure the adsorption equilibria of m‐xylene and n‐butyl acetate on Wessalith® DAY zeolite F20. The equilibrium experiments are performed at different temperatures for both volatile organic compounds (VOCs). The m‐xylene isotherms obtained in this study by the dynamic method are compared to our recently published data in which the static gravimetric method was used in order to test the influence of the experimental technique. Because the adsorption isotherms of m‐xylene were correlated in our previous paper, in this study only the n‐butyl acetate experimental data are correlated with various adsorption isotherm models: Langmuir, Toth and Dubinin equations.

Driving Forces Controlling Host–Guest Recognition in Supercritical Carbon Dioxide Solvent

The formation of supramolecular host-guest complexes is a very useful and widely employed tool in chemistry. However, supramolecular chemistry in non-conventional solvents such as supercritical carbon dioxide (scCO2 ), one of the most promising sustainable solvents, is still in its infancy. In this work, we explored a successful route to the development of green processes in supercritical CO2 by combining a theoretical approach with experiments. We were able to synthesize and characterize an inclusion complex between a polar aromatic molecule (benzoic acid) and peracetylated-β-cyclodextrin, which is soluble in the supercritical medium. This finding opens the way to wide, environmental friendly, applications of scCO2 in many areas of chemistry, including supramolecular synthesis, reactivity and catalysis, micro and nano-particle formation, molecular recognition, as well as enhanced extraction processes with increased selectivity.

Supercritical CO2 extraction of triterpenes from rosemary leaves: Kinetics and modelling

ABSTRACT The pentacyclic triterpene α,β-amyrin is a promising bioactive natural product. Supercritical fluid extraction and fractionation are used to obtain pentacyclic triterpenes compounds from dried rosemary leaves. Experiments were conducted at 50°C and 180 bar, and the fractionation of the extract was accomplished in two separators. The shift to a diffusion-controlled regime occurred when 65% of the total oil was extracted. The moments analysis of kinetic curves indicated that the contribution of the axial dispersion, the external transfer and the internal transfer were 9.16%, 80.24% and 10.58%, respectively. The overall extraction curve was represented using three mathematical models.