Isolation and purification of food-grade C-phycocyanin from Arthrospira platensis and its determination in confectionery by HPLC with diode array detection.

C-Phycocyanin is the major phycobiliprotein in Arthrospira platensis, also known as Spirulina, which is a cyanobacterium used as a dietary supplement because of its powerful effects on body and brain. C-phycocyanin is a blue-colored accessory photosynthetic pigment with multiple applications in food industry as natural dye or additive, and in pharmaceuticals. This study presents a simple protocol for the extraction and purification of food-grade C-phycocyanin from Arthrospira platensis. The cell lysis of cyanobacterium was performed by sonication combined with repeated freezing and thawing cycles. The purification of the crude extract of C-phycocyanin was carried out by ammonium sulfate precipitation followed by ion exchange chromatography resulting in 2.5 purity. The purity of phycocyanobilin chromophore has been tested by UV-visible spectrophotometry by monitoring the absorption after each stage of purification. A high-performance liquid chromatography method has been developed and validated for the determination of food-grade C-phycocyanin. Intra- and interday precision values less than 5.6% and recovery greater than 91.2% indicated high precision and accuracy of the method for analysis of C-phycocyanin. The method has been applied to commercial confectionery of blue color and to the purified protein obtained in the first stage of the study.