Encapsulation of C-phycocyanin in chitosan microparticles improves thermal and storage stability for use as a natural Food colorant

C-Phycocyanin (C-PC), a blue phycobiliprotein from microalgae, is a natural antioxidant and promising food colorant, but its use is limited by poor stability to heat, light, and pH. This study reports the encapsulation of C-PC in spray-dried chitosan (CHT) microparticles to improve its resilience. The microparticles displayed an average diameter of ~3.8 μm, positive ζ-potential (> + 24 mV), and encapsulation efficiency above 36 %. Spectroscopic and thermal analyses indicated the formation of a CHT–C-PC polyelectrolyte hydrogel network, while SAXS/USAXS revealed a heterogeneous porous architecture favoring C-PC retention. Encapsulation significantly enhanced C-PC stability under acidic (pH 2), alkaline (pH 10), and thermal stress, as well as during extended light/dark storage, reducing degradation markers such as color loss, turbidity, and spectral shifts. Stability was also preserved in gelatin matrices, where free C-PC rapidly degraded. Overall, chitosan microencapsulation effectively maintains C-PC integrity, enabling its application as a natural colorant in thermally processed and storage-demanding foods.