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Showing 7 results for Supercritical Fluid

Behrouz Karim, Masoud Rezaei, Nader Bahramifar,
Volume 6, Issue 1 (6-2017)
Abstract

The yield and quality of oil extracted from common kilka (Clupeonella cultriventris caspia) through a novel extraction technique with supercritical fluid CO2 and also ethanol co-solvent extraction at 30 MPa pressure and 58°C temperature of for 90 min were compared. Addition of ethanol co-solvent significantly increased the total oil yield (p˂0.05). Moreover, the qualitative characteristics of the extracted oil with ethanol modified the solvent acidity, peroxide and TBA index considerably less than the oil extracted by supercritical fluid CO2. Fatty acid composition of the oil extracted with the two extraction methods showed there was no significant difference in SFA and PUFA fatty acids (p˃ 0.05). In general, the two methods used in this work didn’t considerably affect the fatty acid composition of the extracted oil.

Volume 11, Issue 3 (9-2023)
Abstract

Aim: The objective of the current study was to evaluate the effectiveness of various extraction techniques, namely supercritical carbon dioxide (SC-CO2), ultrasound, and enzymatic methods, in comparison to the conventional wet reduction method, in terms of oil yield, quality attributes, and fatty acid composition in common kilka oil.
Materials & Methods: Mentioned methods were used to extract fish oil. Then, their quality oxidation, including PV, TBA, FFA, and CD, and fatty acid composition were evaluated.
Findings: The study's findings revealed that the SC-CO2 extraction method exhibited the most favorable outcome in terms of extraction yield, achieving a remarkable rate of 89.6%. The lowest oxidation indexes including PV (1.78 ± 0.19 mmol.kg-1), TBA (0.54 ± 0.03 mg MA.kg-1), FFA (35.49 ± 0.52 mg FFA.g TAG-1), and CD (7.61 ± 0.34 %) was found in oil extracted with SC-CO2 method. The fatty acid profile of oil extracted by SC-CO2 exhibited higher polyunsaturated fatty acid (PUFA) (29.81 ± 0.27) and lower saturated fatty acid (SFA) (27.64 ± 0.20) and monounsaturated fatty acid (MUFA) (34.78 ± 0.67) than those obtained by the other extraction methods (p > 0.05). The n-3/n-6, PUFA/SFA, and EPA + DHA/C16 ratios were higher for oil extracted by SC-CO2 than the other three methods. Conclusion: The common kilka oil, extracted through supercritical carbon dioxide (SC-CO2), can be regarded as an abundant source of crucial polyunsaturated fatty acids belonging to the n-3 series.
 
Seyed Fakhreddin Hosseini, Zahra Eskandari,
Volume 12, Issue 1 (12-2022)
Abstract

Omega-3 polyunsaturated fatty acids (ω-3PUFAs) have gained increasing interest in recent years due to their beneficial effects in maintaining heart health and regulating blood pressure, improving brain function, strengthening memory, and reducing depression. Fish and algae are known as the main sources of ω-3PUFAs. In the meantime, extracting fish oil from less-exploited species or fish waste not only creates higher added value, but also reduces environmental pollution caused by the process of disposal of fishery waste. In this study, the most common methods of oil extraction from marine sources, such as solvent-based methods (Soxhlet, Bligh and Dyer, and Folch Methods), supercritical fluid extraction (SFE) and enzymatic hydrolysis, along with their advantages and disadvantages, were investigated. Among them, Soxhlet extraction provides a high yield of lipids; Of course, choosing the right solvent is the most important factor in the effective extraction of lipids. However, continuous heating at the boiling temperature could lead to lipid oxidation and degradation of heat liable compounds. Therefore, development of alternative extraction and purification methods based on the use of green technologies and the sustainability principles, avoiding the use of organic solvents and high temperatures, is needed in order to produce omega-3 polyunsaturated fatty acids of higher purity and quality. Supercritical fluid extraction with environment-friendly solvents and enzymatic hydrolysis are the most promising green technologies for extracting fish oil, whereas pressurized extractions are suitable for extracting microalgae oil.


Volume 14, Issue 5 (9-2012)
Abstract

Tobacco (Nicotiana tabacum L.) is an important industrial crop and its seeds contain significant amounts of oil. The extraction of oil components using solvent at high pressure, or supercritical fluid (SCF), has received much attention. In the present study, statistical analyses showed that the average extraction yield of seed oil of five tobacco varieties using SFE was 9.33%, which was higher than Sonication (7.75%) and DGF (Deutsche Gesellschaft f_r Fettwissenschaft) standard method B-I5(87) (8.48%), but lower than Soxhlet (13.72%). Also, fatty acids profile of each extracted oil was determined by gas chromatography. Various saturated and unsaturated fatty acids such as lauric (C12:0), myristic (C14:0), palmitic (C16:0), palmitoleic (C16:1), stearic (C18:0), oleic (C18:1), linoleic (C18:2), linolenic (C18:3) and eicosanoic (C20:0) acids were observed in the extracted oils.

Volume 14, Issue 15 (3-2015)
Abstract

The significance of research on the specifications of the supercritical fluids becomes more evident with respect to the increase of their application in different food, chemical, polymer, oil, and gas industries. One of the major specification, is the coefficient of thermal expansion (β) where the ideal gas model was used in most of the processes in which this component is applied; the weakness of this model is that it is unable to make an accurate prediction of this parameter within the range of critical point. For this reason, in this study to determine the coefficient of thermal expansion, Redlich–Kwong equation of state is used and a new relation as a function of temperature, pressure, and compressibility is obtained. Comparing behavior of the curves obtained from this relation with experimental data, exhibits a favorable consistency. Moreover, natural convection heat transfer of the supercritical fluid in a vertical channel at constant temperature walls conditions were considered numerically. The governing equations were solved using the finite-volume method (FVM) and based on the SIMPLE Algorithm. After validation with the earlier studies. Then, the flow and heat transfer characteristics based on the obtained coefficient of thermal expansion were compared with the ideal gas assumptions. Finally, the trend of change in heat transfer coefficient away from the critical point was studied.

Volume 16, Issue 11 (1-2017)
Abstract

Supercritical fluids have substituted non-super critical fluids in some areas of industry because of their unique characteristics and have been the subject of numerous experimental, numerical and analytic studies since their discovery. In this study laminar natural convection between a hot vertical tube with constant temperature and supercritical carbon dioxide with uniform temperature at inlet is simulated by utilizing a numerical model. The simulation is a two-dimensional, pseudo-transient numerical model based on finite volume method. The main objective of this study is to investigate and analyze the effect of severe property variations of supercritical carbon dioxide on the flow and temperature field of natural convection that ultimately affect heat transfer rates with respect to non-critical natural convection. Numerical simulations have been carried out for temperature and pressure ranges of 305K to 312K and 7.5MPa to 9MPa respectively. Span and Wanger’s multi-parameter equation of state have been used directly to determine carbon dioxide properties around pseudo critical temperature for the first time. Results indicate an increased rate of total heat transfer up to 160% near pseudo-critical temperature and 118% in other temperatures for supercritical natural convection with respect to ideal gas assumption.

Volume 16, Issue 94 (12-2019)
Abstract

Drying foods, such as freezing methods and hot air, are not ideal and reduces the nutritional value and is also expensive and is used only for high value food. In this research, drying with supercritical fluid of carbon dioxide was investigated to remove moisture from the figs. In the drying process with supercritical fluid, the structure of food products is maintained during drying. The design of the experiment was carried out in a factorial arrangement using Design Expert software and analysis variance table to determine the effect of three pressure parameters, temperature, and time to measure the removal rate of moisture. The calculated factorial model was meaningful and able to select the best drying parameters. In optimum conditions, the highest yield (78.109%) with the desirability of 0.992 at 20 MPa, 60 °C and 120 minutes duration. The results showed that the drying of figs during the whole drying period is carried out at the downstream stage, which indicates that the drying of these materials, the internal moisture control, controls the rate of drying and mass transfer. In this study, by solving the second Fick's law and in the range of pressure and temperature tested, with the assumption of the spherical of the fig using the Crank equation, the amount of moisture diffusion coefficient between 4.51× 10-10 and 0.18 × 10 -10 m2/s were obtained. The fig's drying rate was also calculated. Increasing temperature and pressure caused to increase the drying rate.


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