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[Display omitted] • A variety of approaches for the extraction of lipids from microalgae were reviewed. • The bioactivity of microalgae lipids is summarized. • Innovative techniques have advantages in improving yield and reducing pollution. Microalgae, as a photosynthetic autotrophic organism, contain a variety of bioactive compounds, including lipids, proteins, polysaccharides, which have been applied in food, medicine, and fuel industries, among others. Microalgae are considered a good source of marine lipids due to their high content in unsaturated fatty acid (UFA) and can be used as a supplement/replacement for fish-based oil. The high concentration of docosahexaenoic (DHA) and eicosapentaenoic acids (EPA) in microalgae lipids, results in important physiological functions, such as antibacterial, anti-inflammatory, and immune regulation, being also a prerequisite for its development and application. In this paper, a variety of approaches for the extraction of lipids from microalgae were reviewed, including classical and innovative approaches, being the advantages and disadvantages of these methods emphasized. Further, the effects of microalgae lipids as high value bioactive compounds in human health and their use for several applications are dealt with, aiming using green(er) and effective methods to extract lipids from microalgae, as well as develop and extend their application potential. [ABSTRACT FROM AUTHOR]

Abstract: There is significant commercial interest in oil extraction from krill because it is rich in omega-3 polyunsaturated fatty acids (n-3 PUFA) such as eicosapentaenoic (EPA, 20:5n3) and docosahexaenoic (DHA, 22:6n3) acids. The objectives were to determine oil extraction efficiency using different solvent systems and the composition of extracted oil and spent krill following extraction. Extraction efficiency was the highest (P <0.05) for one-step extraction using freeze-dried krill with 1:12 or 1:30 krill:solvent ratio (w:v) compared to Folch, Soxhlet, and conventional two-step extraction. Extracted oils contained predominantly phospholipids (20–33%), polar non-phospholipids (64–77%), and minor triglycerides (1–3%). Triglycerides contained much less (P <0.05) total n-3 (4.0%), DHA (1.1%), and EPA (2.3%), but more (P <0.05) saturated FA (38.7%) than phospholipids (total n-3-47.4%, DHA-18.0%, EPA-28.2%, saturated FA-23.5%). Antioxidant capacity of krill oil extracted by one-step extraction (9.4–14.2μmol Trolox Equivalents/ml oil) was generally similar to antioxidant capacity of krill oil extracted by ethanol (22.9), but greater (P <0.05) than antioxidant capacity of krill oil extracted by acetone (1.2) and Folch method (1.5). The spent krill following oil extraction contained protein (72.9–75.8%, dry basis). Based on the extraction efficiency and composition of the extracted oil, the one-step extraction using 1:12 krill:solvent ratio is recommended. [ABSTRACT FROM AUTHOR]

• The alga Phaeodactylum tricornutum is a promising source of omega-3-rich fatty acids. • Lipid biosynthesis can be stimulated by nutrient depletion and increased CO 2 supply. • Eicosapentaenoic acid synthesis can be induced by CO 2 and urea supply and high light. • P. tricornutum in a biorefinery can produce omega-3-rich oil and high-value protein. Diatoms are a major group of high omega 3-fatty acid producing algae that play a key role in global climate change and ecosystem function. Phaeodactylum tricornutum is one of only two diatoms whose genomes have been completely sequenced, leading to metabolic engineering of high eicosapentaenoic acid producing strains. Based on its rapid growth, high lipid content, and especially omega-3 long chain unsaturated fatty acids, P. tricornutum exhibits a large commercial potential. However, until now, it is predominately produced as feed for the aquaculture industry, rather than food supplement. This review compares the change of P. tricornutum lipid composition under different treatments, and identifies suitable lipid induction, cultivation and harvesting methods for industry adoption. If produced in a biorefinery setting, P. tricornutum has strong potential for value generation from human health products (omega-3-rich oil and high-value protein) with cost estimates of AU$6.14 per kg dry weight and AU$20.47 for omega-3-rich oil. [ABSTRACT FROM AUTHOR]