Biological and economic advantages of C-Phycocyanin production from red algae (Rhodophyta), yield optimization and sustainability strategies: a systematic review

Microalgae are gaining interest as sustainable biofactories for the industrial-scale production of Phycocyanin (PC), a phycobiliprotein (PBP) with significant antioxidant, anti-inflammatory, and nutraceutical properties. Among them, red extremophilic species such as Galdieria spp. have emerged as particularly promising sources due to their ability to thrive in harsh conditions, enabling the production of high-purity C-Phycocyanin (C-PC) with reduced contamination risks. The growing demand for natural pigments, supported by a global market forecasted to expand at a compound average growth rate (CAGR) of 7% through 2030, calls for scalable, cost-efficient, and environmentally sustainable strategies.This review critically examines upstream and downstream approaches for C-PC production from Rhodophyta, including cultivation regimes (autotrophic, heterotrophic, and mixotrophic), extraction and purification techniques, with a focus on operational performance, purity index, and process sustainability. Finally, we highlight persistent methodological gaps, such as protocol heterogeneity and the lack of standardization, and propose integrated strategies to support future biotechnological applications and large-scale deployment. The development of unified quality benchmarks, robust production protocols, and biorefinery models is essential to unlock the full commercial potential of red algal-derived C-PC.