Recent advances in non-conventional techniques for extraction of phycobiliproteins and carotenoids from microalgae

The diverse colors and significant health benefits of some natural pigments, such as phycobiliproteins and carotenoids, have made them valuable compounds in various industries, including food, cosmetics, poultry, and pharmaceutical. Phycocyanin, astaxanthin, β-carotene, and lutein are the main examples of high-value pigments found in natural resources, specifically microalgae. The convenience of using microalgae as a promising resource for these four pigments have been investigated in recent decades. The solvent extraction method is one of the most widely used techniques for separating natural components such as pigments from microalgal sources. However, high solvent and energy consumption, toxicity of some solvents, and low extraction efficiency are some of the disadvantages of the solvent extraction process. Several extraction procedures called green techniques have been introduced and developed as alternatives to conventional solvent extraction to overcome the challenges of traditional extraction. The green techniques include ultrasound-assisted extraction, microwave-assisted extraction, pulsed-field electric-assisted extraction, pressurized liquid extraction, aqueous two-phase system, and supercritical fluid extraction. This review introduces the green extraction techniques and summarizes some of the advantages and drawbacks of these procedures compared to traditional extraction methods. Also, recent advances in the novel extraction processes for isolating phycocyanin, astaxanthin, β-carotene, and lutein are discussed.