Effect of light and preservatives on the stability of the phycocyanin from the extremophilic red microalgae Cyanidioschyzon merolae

Synthetic dyes are replaced more and more in food products by natural pigments. A growing number of consumers are concerned with the potential health risk and behavior problems related to synthetic dyes. The phycocyanin of the cyanobacterium Arthospira platensis is the only natural blue pigment commercially available. The thermoacidophilic red microalgae Cuanidioschyzon merolae could provide an alternative phycocyanin source. As C. merolae grows at relatively high temperatures (45 to 56°C), the phycocyanin has a high thermostability even at relatively low pH. The stability of the C. merolae phycocyanin was determined for several products of relevant parameters. Average daylight (300-500 Lux) did not significantly affect the stability, while intense light (20,000 Lux) reduced the half-life to 35 hours. The preservatives such as glucose, sucrose, fructose, and sorbitol improved the stability of C. merolae phycocyanin considerably, with 20% glucose resulting in no loss of color at all. The results show that C. merolae phycocyanin can be used in various food products as a natural blue colorant.