Is downstream ultrafiltration enough for production of food-grade phycocyanin from Arthrospira platensis?

Phycocyanin (PC), a natural blue pigment found in the cyanobacterium Arthrospira platensis, has anticancer, anti-inflammatory, and antioxidant properties. The purity of PC is the key factor for its application in the food, pharmaceutical and medical industries; however, the purification processes needed to achieve high purity can impact its bioactivity. This study evaluates whether microfiltration (MF) or ultrafiltration (UF) can be used to produce PC with food-grade purity. MF and UF following freeze-thaw extraction of PC from A. platensis biomass resulted in a low product purity, with other cellular constituents forming a cake on the membrane surface during the filtration process and preventing the concentration of PC. Phosphate buffer extraction resulted in more PC (65.5 mg g−1) with purity of 0.53. When the UF was followed by one step of diafiltration, purity was further enhanced to 0.76. However, the purification resulted in a 30% loss of antioxidant activity. This study demonstrates that phosphate buffer extraction followed by UF and one step of DF is suitable to produce food-grade PC from A. platensis, with the advantage of only requiring a single piece of equipment to perform the purification.