Application of supercritical CO2 in lipid extraction – A review

Measurement and correlation study of silymarin solubility in supercritical carbon dioxide with and without a cosolvent using semi-empirical models and back-propagation artificial neural networks

The solubility data of compounds in supercritical fluids and the correlation between the experimental solubility data and predicted solubility data are crucial to the development of supercritical technologies. In the present work, the solubility data of silymarin (SM) in both pure supercritical carbon dioxide (SCCO₂) and SCCO₂ with added cosolvent was measured at temperatures ranging from 308 to 338 K and pressures from 8 to 22 MPa. The experimental data were fit with three semi-empirical density-based models (Chrastil, Bartle and Mendez-Santiago and Teja models) and a back-propagation artificial neural networks (BPANN) model. Interaction parameters for the models were obtained and the percentage of average absolute relative deviation (AARD%) in each calculation was determined. The correlation results were in good agreement with the experimental data. A comparison among the four models revealed that the experimental solubility data were more fit with the BPANN model with AARDs ranging from 1.14% to 2.15% for silymarin in pure SCCO₂ and with added cosolvent. The results provide fundamental data for designing the extraction of SM or the preparation of its particle using SCCO₂ techniques.

The effect of chamomile extract obtained in supercritical carbon dioxide conditions on physicochemical and usable properties of pharmaceutical ointments

The study investigated the effect of chamomile extract obtained in supercritical carbon dioxide conditions on the basic properties of pharmaceutical ointments. A total of five formulations were designed and prepared, differing in the weight ratio of sunflower oil to chamomile extract (5:0, 3.5:1.5, 2.5:2.5, 1.5:3.5 and 0:5). An increase in the concentration of chamomile extract was found to be accompanied by a decrease in hardness, adhesive power and flow limit. Based on viscosity measurements it was shown that ointments containing the hydrophobic plant extract under study were prone to larger drops in viscosity under the effect of the set shear rate. It was determined that from the viewpoint of ointment spreadability and application to the skin, the optimum concentration of chamomile extract for the studied formulations should be within the range of 1.5-2.5%. Furthermore, the addition of chamomile extract to ointments was found to give samples a yellow-green color. Green was observed to be the dominant color, and its saturation and shade varied for different formulations.

Single step extraction and derivatization of intramuscular lipids for fatty acid Ultra Fast GC analysis: application on pig thigh

Two different methods for single step transesterification from pig meat without fat extraction have been tested. Freeze-drying of the meat with and without anhydrous salt, followed by a base-catalyzed transmethylation (KOH/MeOH) was carried out. Both methods were compared with the standard Folch procedure of fat extraction followed by transmethylation. The methods were tested on a complete sample set of biceps femoris of pig thigh, used for the production of dry-cured ham. The set was divided in three subgroups according to total fat content. Both derivatization protocols on freeze-dried pork muscle were proven to be a valid alternative to the Folch procedure for FAME analysis. Freeze-drying method offered several advantages in comparison with the Folch procedure, including a lower solvent requirement, and process temperature, as well as considerable saving of time. In freeze-drying, the addition of an anhydrous salt (Na₂SO₄) gave more friable samples which resulted in higher yields for some fatty acids, particularly evident in the case of tissues with high lipid content.

Ultrahigh pressure extraction of bioactive compounds from plants-A review

Extraction of bioactive compounds from plants is one of the most important research areas for pharmaceutical and food industries. Conventional extraction techniques are usually associated with longer extraction times, lower yields, more organic solvent consumption, and poor extraction efficiency. A novel extraction technique, ultrahigh pressure extraction, has been developed for the extraction of bioactive compounds from plants, in order to shorten the extraction time, decrease the solvent consumption, increase the extraction yields, and enhance the quality of extracts. The mild processing temperature of ultrahigh pressure extraction may lead to an enhanced extraction of thermolabile bioactive ingredients. A critical review is conducted to introduce the different aspects of ultrahigh pressure extraction of plants bioactive compounds, including principles and mechanisms, the important parameters influencing its performance, comparison of ultrahigh pressure extraction with other extraction techniques, advantages, and disadvantages. The future opportunities of ultrahigh pressure extraction are also discussed.

Production of methyl ester from two microalgae by two-step transesterification and direct transesterification

The efficiency of oil extraction from Chlorella sp. and Scenedesmus sp. using different cell disruption and solvent system was investigated. The ultrasound cell disruption method showed the maximum oil extraction in both algae. Oil extraction with hexane resulted in maximum oil yield for both algae. The kinetic parameters were studied and the extraction followed the first-order kinetics. The activation energy and thermodynamic activation parameters were calculated for both microalgae and the results suggested that the extraction was endothermic, irreversible and spontaneous. The methyl ester yields by two-step transesterification and direct transesterification were 95 and 96% for Scenedesmus sp. and 89 and 92% for Chlorella sp. respectively. Both methods had similar net energy consumption suitable for industrial application. The methyl ester properties were analysed in comparison with those of American Society for Testing and Materials (ASTM) D6751 standards.

Selective improvement of peptides imaging on tissue by supercritical fluid wash of lipids for matrix-assisted laser desorption/ionization mass spectrometry

There is a high analytical demand for improving the detection sensitivity for various peptides in matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI-IMS) because exhaustive distribution analyses of various peptides could help to reveal the function of peptides in vivo. To improve the sensitivity of peptide detection, we used supercritical fluid of CO₂ (scCO₂) as washing solvent for a pretreatment to remove lipids. We evaluated whether our wash method using scCO₂ with an entrainer improved the detection of peptides and suppressed lipid detection in MALDI-IMS. Our analysis revealed that the signal intensities of peptides such as m/z 3339.8, 3530.9, 4233.3, 4936.7, and 4963.7 were increased in scCO₂-washed samples. The greatest improvement in the signal-to-noise ratio (S/N) was found at m/z 4963.7, which was identified as thymosin β4, with the S/N reaching almost 190-fold higher than the control. Additionally, all of the improved signals were associated with the morphologic structure. Our method allows us to analyze the distribution of molecules, especially in the region of m/z 3000-5200. For these improvements, the polarity difference between scCO₂ and the matrix solution used was considered as a key. A wider variety of molecules can be analyzed in the future due to this improvement of the detection sensitivity by optimizing the polarity of scCO₂ with various entrainers. Graphical Abstract Mass spectra of m/z 4900-5000 obtained from a scCO₂-washed tissue (upper, blue) and a control tissue (lower, red). Ion distribution of the signals at m/z 4936.7 and m/z 4963.7 specifically ditected from scCO₂-washed samples.

Production Strategies and Applications of Microbial Single Cell Oils

Polyunsaturated fatty acids (PUFAs) of the ω-3 and ω-6 class (e.g., α-linolenic acid, linoleic acid) are essential for maintaining biofunctions in mammalians like humans. Due to the fact that humans cannot synthesize these essential fatty acids, they must be taken up from different food sources. Classical sources for these fatty acids are porcine liver and fish oil. However, microbial lipids or single cell oils, produced by oleaginous microorganisms such as algae, fungi and bacteria, are a promising source as well. These single cell oils can be used for many valuable chemicals with applications not only for nutrition but also for fuels and are therefore an ideal basis for a bio-based economy. A crucial point for the establishment of microbial lipids utilization is the cost-effective production and purification of fuels or products of higher value. The fermentative production can be realized by submerged (SmF) or solid state fermentation (SSF). The yield and the composition of the obtained microbial lipids depend on the type of fermentation and the particular conditions (e.g., medium, pH-value, temperature, aeration, nitrogen source). From an economical point of view, waste or by-product streams can be used as cheap and renewable carbon and nitrogen sources. In general, downstream processing costs are one of the major obstacles to be solved for full economic efficiency of microbial lipids. For the extraction of lipids from microbial biomass cell disruption is most important, because efficiency of cell disruption directly influences subsequent downstream operations and overall extraction efficiencies. A multitude of cell disruption and lipid extraction methods are available, conventional as well as newly emerging methods, which will be described and discussed in terms of large scale applicability, their potential in a modern biorefinery and their influence on product quality. Furthermore, an overview is given about applications of microbial lipids or derived fatty acids with emphasis on food applications.

Improvement in the Safety of Use of Hand Dishwashing Liquids Through the Addition of Hydrophobic Plant Extracts

We investigated the effect of hydrophobic extract concentration on the safety of using hand dishwashing liquids (HDL). A series of formulations was prepared, differing in the concentration of the hydrophobic chamomile extract obtained in supercritical CO₂ conditions (from 0 to 0.7 %). We found that an increase in the concentration of the extract led to a decrease in the zein number, and reduced changes in the pH level of bovine serum albumin solution (i.e., two parameters determining the irritant activity of the formulations). It was also found that the additives reduced transepidermal water loss and improved the skin hydration level. Based on the findings of the study, a mechanism has been proposed, according to which hydrophobic plant extracts form aggregates in the volume phase of the washing bath. The surface of the aggregates is the adsorption area for surfactant monomers responsible for the irritant effect. Increasing the addition of the extract was shown to reduce the negative impact of the formulations on the skin of the hands, thus contributing to a greater safety of use of HDL.

Potent in vivo anticancer activity and stability of liposomes encapsulated with semi-purified Job's tear (Coix lacryma-jobi Linn.) extracts on human colon adenocarcinoma (HT-29) xenografted mice

The in vivo anticancer activity and stability of liposomes encapsulated with semi-purified Job's tear (Coix lacryma-jobi Linn.) extracts (S5L), prepared by supercritical carbon dioxide fluid technique, on human colon adenocarcinoma (HT29) xenografted mice were investigated. For the stability and the physicochemical characteristics, S5L showed a high stability of pH, good dispersibility, small particle size and stable zeta potential. Liposomes can protect linoleic acid in the extract comparing with the free S5. S5L kept at 4 °C for 3 months showed the highest linoleic acid content of 63.50%, whereas at 45 °C, the lowest linoleic acid content of 42.66% was observed. The anticancer activity and toxicity on xenografted mice were observed for 14 days. At the end of the experiment, the relative tumor volume (RTV) in the S5L-treated xenografted mice showed a significant RTV reduction. The high dose of S5 and S5L were potent with the highest inhibition of tumor growth of 48.67 and 54.75%, which was 86.94% and 97.81% of 5-fluorouracil, respectively. The apoptotic activity was shown in xenografted mice treated with S5 at medium and high dose, S5L, 5-fluorouracil and commercial product. All treated xenografted mice showed no toxic signs and symptoms, abnormality of internal organs histopathology and blood chemistry. This study has demonstrated the high physicochemical stability of liposomes encapsulated with semi-purified Job's tear extract and their potent anticancer activity on human colon adenocarcinoma xenografted model with the potential for further development to anticolon cancer drug.

Genotoxicity of rice bran oil extracted by supercritical CO2 extraction

Rice bran oil extracted by supercritical CO2 extraction (RB-SCE) reportedly exhibits pharmacological activities such as antioxidant and in vivo hair growth-inducing effects. Such activities raise the possibility of the development of novel hair growth-inducing agents using RB-SCE. The aim of this study was to investigate the potential genotoxic effects of RB-SCE in three short-term mutagenicity assays (bacterial reverse mutation assay, in vitro mammalian chromosomal aberration test, and in vivo micronucleus assay). RB-SCE showed no genotoxicity in the bacterial reverse mutation assay up to 5000 mg/plate and in the in vivo micronucleus test up to 600 mg/kg body weight. However, at 120 µg/mL with S9 mix and 200 µg/mL without S9 mix RB-SCE showed significantly different genotoxicity than the negative control in the in vitro chromosome aberration test. The induction of chromosomal aberrations under the present conditions may have no biological significance. We have herein demonstrated that RB-SCE can be regarded as a non-genotoxic material based on the available in vivo and in vitro results.

A Methionine Deficient Diet Enhances Adipose Tissue Lipid Metabolism and Alters Anti-Oxidant Pathways in Young Growing Pigs

Methionine is a rate-limiting amino-acid for protein synthesis but non-proteinogenic roles on lipid metabolism and oxidative stress have been demonstrated. Contrary to rodents where a dietary methionine deficiency led to a lower adiposity, an increased lipid accretion rate has been reported in growing pigs fed a methionine deficient diet. This study aimed to clarify the effects of a dietary methionine deficiency on different aspects of tissue lipid metabolism and anti-oxidant pathways in young pigs. Post-weaned pigs (9.8 kg initial body weight) were restrictively-fed diets providing either an adequate (CTRL) or a deficient methionine supply (MD) during 10 days (n=6 per group). At the end of the feeding trial, pigs fed the MD diet had higher lipid content in subcutaneous adipose tissue. Expression levels of genes involved in glucose uptake, lipogenesis but also lipolysis, and activities of NADPH enzyme suppliers were generally higher in subcutaneous and perirenal adipose tissues of MD pigs, suggesting an increased lipid turnover in those pigs. Activities of the anti-oxidant enzymes superoxide dismutase, catalase and glutathione reductase were increased in adipose tissues and muscle of MD pigs. Expression level and activity of the glutathione peroxidase were also higher in liver of MD pigs, but hepatic contents in the reduced and oxidized forms of glutathione and glutathione reductase activity were lower compared with control pigs. In plasma, superoxide dismutase activity was higher but total anti-oxidant power was lower in MD pigs. These results show that a dietary methionine deficiency resulted in increased levels of lipogenesis and lipolytic indicators in porcine adipose tissues. Decreased glutathione content in the liver and coordinated increase of enzymatic antioxidant activities in adipose tissues altered the cellular redox status of young pigs fed a methionine-deficient diet. These findings illustrate that a rapidly growing animal differently adapts tissue metabolisms when facing an insufficient methionine supply.

Polar Lipid Profile of Nannochloropsis oculata Determined Using a Variety of Lipid Extraction Procedures

Lipid compositions obtained from microalgae species are affected by both the cultivation conditions and the extraction method used. In this study, the extraction of lipids from Nannochloropsis oculata using traditional and modern extraction technologies with several solvents has been compared. Because important polyunsaturated fatty acids are bound to polar lipids, these polar lipids were the main focus of this study. The dominant compounds in the glycolipid fractions were monogalactosyldiglycerides and digalactosyldiglycerides bearing fatty acid chains containing at least one site of unsaturation. Phosphatidylcholine and trimethylhomoserines were detected in the phospholipid fractions. The fatty acid profile comprised large fractions of C16:0, C16:1, C20:5, and C18:3. Extraction of specific compounds was determined by extraction efficiency as well as differences in the selectivity of the method used. The composition derived from a glycolipid fraction was observed to be affected by the method used to a greater extent than the phospholipid fraction.

Pilot-scale subcritical solvent extraction of curcuminoids from Curcuma long L

Curcuminoids consisted curcumin, demethoxycurcumin and bisdemethoxycurcumin, were extracted from turmeric using subcritical solvent by varying conditions of temperature (110-150 °C), time (1-10 min), pressure (5-100 atm), solid-to-solvent ratio, and mixing ratio of solvent. Preliminary lab-scale experiments were conducted to determine the optimum extraction temperature and mixing ratio of water and ethanol for the pilot-scale extraction. The maximum yield of curcuminoids in the pilot-scale system was 13.58% (curcumin 4.94%, demethoxycurcumin 4.73%, and bisdemethoxycurcumin 3.91% in dried extracts) at 135 °C/5 min with water/ethanol mixture (50:50, v/v) as a solvent. On the other hand, the extraction yields of curcuminoids were obtained as 10.49%, 13.71% and 13.96% using the 50%, 95% and 100% ethanol, respectively, at the atmospheric condition (60 °C/120 min). Overall results showed that the subcritical solvent extraction is much faster and efficient extraction method considering extracted curcuminoids contents and has a potential to develop a commercial process for the extraction of curcuminoids.