Amongst the current alternatives, algae were proven to be a promising source of biofuel, which is renewable and capable of meeting world demand for transportation fuels. However, a suitable lipid extraction method that efficiently releases the lipids from different algal strains remains a bottleneck. The multifarious pretreatment methods are prevalent in this field of lipid extraction, and therefore, this article has critically reviewed the various lipid extraction methods for ameliorating the lipid yield from algae, irrespective of the strains/species. Physical, mechanical, and chemical are the different types of pretreatment methods. In this review, methodologies such as homogenization, sonication, Soxhlet extraction, microwave treatment, and bead-beating, have been studied in detail and are the most commonly used methods for lipid extraction. Specific advanced/emerging processes such as supercritical CO2 extraction, ionic liquid, and CO2 switchable solvent-based algal lipid extraction are yet to be demonstrated at pilot-scale, though promising. The extraction of lipids has to be financially conducive, environmentally sustainable, and industrially applicable for further conversion into biodiesel. Hence, this paper discusses variable pretreatment for lipid extraction and imparts a comparative analysis to elect an efficient, economically sound lipid extraction method for pilot-scale biodiesel production.
Keywords: Algae; Ionic liquids; Lipid extraction; Sonication; Supercritical CO(2) extraction; Switchable polarity solvent.
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