Developments in oil extraction from microalgae.

TLDR: An overview, based on the last 10 years, of advances made in technologies for extracting and purifying microalgae oil is presented, and solvent extraction technologies with extraction alternatives such as mechanical milling and pressing, enzymatic and supercritical fluid extraction are compared.

Abstract: Microalgae are a diverse group of organisms with significant potential for industrial applications: as feedstock in aquaculture as well as in the production of valuable bioproducts such as lipids, carotenoids and enzymes. Lately, developments in molecular biology have improved production yields of algae bioproducts, thus increasing their industrial relevance. Additionally, variations in bioprocessing factors (i.e. temperature, pH, light, carbon source, salinity, nutrients, etc.) have been used to enhance both biomass and specific bioproducts' productivities. Particularly, microalgae have increasingly gained research interest as a source of specialty lipids such as arachidonic, eicosapentaenoic and docosahexaenoic acids, which are often reported in literature to provide several health benefits. Moreover, there has been a recent resurgence in interest in microalgae as an oil producer for biofuel applications. Significant advances have also been made in upstream processing to generate cellular biomass and oil. However, extracting and purifying oil from algae continues to prove a significant challenge in producing both microalgae bioproducts and biofuel, as microbial oil extraction is relatively energy-intensive and costly. Thus, developing inexpensive and robust oil extraction and purification processes is a major challenge facing both the microalgae to bioproduct, and biofuel industries. This paper presents an overview, based on the last 10 years, of advances made in technologies for extracting and purifying microalgae oil. We compared solvent extraction technologies with extraction alternatives such as mechanical milling and pressing, enzymatic and supercritical fluid extraction. We also reviewed recent advances based on molecular engineering of microbes to aid oil extraction. Downstream processing for the potential commercial production of microalgae oil not only must consider economic costs, but should also consider minimizing environmental impacts in order to attain sustainable production processes.