Extraction of C-phycocyanin from Arthrospira (Spirulina) and its thermal stability with citric acid

C-phycocyanin (C-PC) is a blue pigment often found in cyanobacteria. It has commercial and biotechnological value as a nutraceutical for pharmaceutical and biomedical research, as well as a natural colorant for the cosmetic industry. Cyanobacteria from the Arthrospira (Spirulina) genus are one of the major sources of C-phycocyanin with up to 20% protein fraction. The biomass-solvent ratio, buffer concentration, temperature, and time regarding C-phycocyanin concentration, extract purity, and yield of C-phycocyanin were evaluated. The optimum extraction conditions for Arthrospira platensis were determined as a biomass-solvent ratio of 0.06 g mL−1 at 25 °C for 24 to 48 h. Temperature is an important factor in C-phycocyanin degradation. Citric acid was added as an edible preservative to increase the thermal stability of C-phycocyanin extracted from A. platensis, followed by incubation at 80 °C for 1 h. The initial concentration of C-phycocyanin with citric acid was reduced from 65 to 19% within 1 h; in contrast, the remaining C-phycocyanin concentration without citric acid reduced from 51 to 11%. The use of citric acid as an edible preservative increased the stability of C-phycocyanin in high thermal processing applications and extraction.