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

Abstract 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.