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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.
 

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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.

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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.