Industrial Extraction of Microalgal Pigments

Pigments are valuable commodity products that have found many applications in pharmaceutical, food and cosmetic industries. Under different light and nutrient regimes, microalgal cells can be cultivated to accumulate a broad range of valuable pigments throughout their life cycle. The effective recovery of these pigments is critical to the development of a commercially viable and sustainable microalgal bio-industry. In this chapter, the recovery of pigments from microalgal biomass is examined. The chapter starts by evaluating the range of technological options that are currently available for rupturing microalgal cell walls to release intracellular pigments (high-pressure homogenisation, bead milling, ultrasonication, pulse electric field, osmotic shock, microwave, enzymatic treatments and chemical treatments). It then reviews a number of extraction technologies that can be used to extract the released pigments from ruptured biomass (organic solvent extraction, pressurised solvent extraction, ionic liquid extraction and supercritical carbon dioxide extraction) and examines the different biomass processing pathways that have been recently studied for the recoveries of industrially valuable pigments from algal sources (astaxanthin, β-carotene, phycoerythrin, phycocyanin). The last part of the chapter evaluates the industrial scalability of pigment extraction in the context of a biorefinery system that enables energy-efficient and cost-effective co-production of lipids, proteins and pigments from microalgal biomass.