Temperature and pH play an important role in the stability of phycocyanin, a natural blue colorant. Systematic investigations showed the maximum stability of phycocyanin was in the pH range 5.5-6.0. Incubation at temperatures between 47 and 64 degrees C caused the concentration (C-R) and half-life of phycocyanin in solution to decrease rapidly. The C-R value remained at approximately 50% after incubating for 30 min at 59 degrees C. After heating at 60 degrees C for 15 min, the C-R value of phycocyanin at pH 7.0 was maintained at around 62-70% when 20-40% glucose or sucrose was added, and the half-life increased from 19 min to 30-44 mm. 2.5% sodium chloride was found to be an effective preservative for phycocyanin at pH 7.0 as a C-R value of 76% was maintained and the half-life of 67 min was increased. (C) 2012 Elsevier Ltd. All rights reserved.