In the history of protein crystallization, one of the earliest purposes of crystallization was separation and purification of proteins from mixtures. Nowadays, the rising demand for pure proteins in biomedicine, biochemical research, and the food industry highlights the need for cost-effective purification methods. Although chromatography dominates large-scale processes, crystallization offers a low-cost alternative for obtaining highly purified products, though its industrial implementation remains challenging.^[1] In this context, crystallization is re-emerging as a promising strategy due to its inherent selectivity and potential for cost-effective scalability.

Phycobiliproteins (PBPs) are water-soluble light-harvesting pigment-proteins from cyanobacteria and red algae.^[2] In addition to their role in photosynthetic energy capture, they exhibit diverse biological activities, including antioxidant, antibacterial, and anticancer effects, which make them promising candidates for biotechnological applications in fields such as biomedicine, bioenergy, and scientific research.^[3] Among PBPs, C-phycocyanin (C-PC) is a high-value pigment widely used in health, food, and analytical applications. Current downstream processes, however, rely mostly on multistep chromatographic workflows that increase production costs and complexity.^[4]

Through this work, we are exploring protein crystallization as an alternative route for C-PC purification from raw materials, aiming to establish its feasibility as a scalable method that integrates high product quality with improved process sustainability. Preliminary results support the potential of crystallization to enhance recovery of C-PC, thereby contributing to more efficient bioprocessing.