Green and efficient method to acquire high-value phycobiliprotein from microalgal biomass involving deep eutectic solvent-based ultrasound-assisted extraction

Phycoerythrin (PE) is a phycobiliprotein holding great potential as a high-value food colorant and medicine. Deep eutectic solvent (DES)-based ultrasound-assisted extraction (UAE) was applied to extract B-PE by disrupting the resistant polysaccharide cell wall of Porphyridium purpureum. The solubility of cell wall monomers in 31 DESs was predicted using COSMO-RS. Five glycerol-based DESs were tested for extraction, all of which showed significantly higher B-PE yields by up to 13.5 folds than water. The DES-dependent B-PE extraction efficiencies were proposedly associated with different cell disrupting capabilities and protein stabilizing effects of DESs. The DES-based UAE method could be considered green according to a metric assessment tool, AGREEprep. The crude extract containing DES was further subjected to aqueous two-phase system, two-step ammonium sulfate precipitation, and ultrafiltration processes. The final purified B-PE had a PE purity ratio of 3.60 and a PC purity ratio of 0.08, comparable to the purity of commercial products. •COSMO-RS predicted the solubility of microalgal cell wall components in DESs.•High solubility-predicted DESs could disrupt the resistant cell wall effectively.•PGly-based UAE of cells could produce the B-PE extract the most efficiently.•PGly-based UAE method was considered green based on AGREEprep evaluation.•High-purity B-PE was obtained from DES extract by ATPS, followed by ASP and UF.