Sustainable processing of microalgae protein: Design of biphasic partitioning systems based on natural deep eutectic solvents for C-phycocyanin recovery from model aqueous solutions

• Published in: Separation and purification technology 2025-01, Vol.353, p.128510, Article 128510
• Main Authors: Pereira, Bruno A., Matos, Cristina T., Costa, Luís, Ferreira, Luísa M., Crespo, João G., Brazinha, Carla
• Format: Article
• Language: English
• Subjects: C-phycocyanin (C-PC); Extraction with biphasic systems; Microalgae biorefinery; natural deep eutectic solvent (NADES); Protein partitioning
• ISSN: 1383-5866
• DOI: 10.1016/j.seppur.2024.128510

[Display omitted] •Biphasic extraction with NADES is efficient for C-phycocyanin recovery.•Salting-out and NADES hydrophobicity are key factors in protein partitioning.•Interfacial tension, crucial for interface stability in protein extraction with biphasic systems. The development of sustainable protein sources is imperative for addressing the global challenge of food/feed security. Microalgae, which may be sustainably cultivated, are a promising source of proteins, gaining a progressive acceptance among consumers. The purpose of this work is to study the recovery of the protein C-phycocyanin from the microalga Arthrospira platensis (Spirulina), using a biphasic extraction system composed of sustainable solvents. The extraction system studied involves a feed phase, consisting of an aqueous salt solution and the target protein, and an extracting phase composed of a Natural Deep Eutectic Solvent (NADES) with affinity to the target protein. The performance of a specific NADES depends on the characteristics of the components of the NADES, in terms of its hydrophobicity/hydrophilicity balance, aiming the highest possible partitioning coefficient towards C-phycocyanin. It is also important to assure that the NADES phase selected presents a moderate viscosity and leads to a stable interface when in contact with the aqueous feed phase (i.e., presenting a measurable interfacial tension). In this work, after an extensive screening work of more than 71 combinations, the most overall performing combination is presented. This system shows a high partitioning coefficient of 29.4 ± 0.3 and an extraction yield of 99 % for C-phycocyanin (C-PC), demonstrating that the salting-out effect of the phosphate buffer and the hydrophobic character of NADES play a key role in this protein partitioning and recovery.