Selective extraction of carotenoids and proteins from Chlorella vulgaris

Abstract. Microalgae are a great source of proteins, lipids, carbohydrates and other metabolites like carotenoids. Significant research and development efforts have focused on advances in upstream technologies to increases in biomass productivity and oil accumulation through media optimization and molecular manipulation of metabolic pathways. Although some biomass and oil productivity improvements have been achieved, life cycle and techno- economic analyses reported in the past five years clearly indicate that unless multiple high-value products like protein and carotenoids are extracted, algal production platform is not sustainable. This study explores selective extraction carotenoids followed by proteins from microalgae Chlorella vulgaris. Bead-milling and high-pressure homogenization were more effective than sonication in extraction of protein from C. vulgaris. Biomass to solvent ratio of 1:5 and 2 stages were optimum for maximum extraction of chlorophyll and carotenoids. Protein fraction concentrated using a 300 kDa MWCO membrane from ethanol-treated cells has comparable amino acid profile to control sample and matches up to the recommendations by FAO/WHO. For complete release of protein after ethanol extraction, a basic pH (12) is more effective than a neutral pH (7).