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J Appl Phycol. 2017;29(3):1233-1239. doi: 10.1007/s10811-016-1007-0. Epub 2016 Nov 21.

Thermostable phycocyanin from the red microalga Cyanidioschyzon merolae, a new natural blue food colorant.

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Aquatic Biotechnology and Bioproduct Engineering Department, Engineering and Technology Institute Groningen (ENTEG), University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands.
Research Center for Biotechnology, Indonesian Institute of Sciences (LIPI), Jl. Raya Bogor KM 46, 16911 Cibinong, Bogor, Indonesia.


The demand for natural food colorants is growing as consumers question the use of artificial colorants more and more. The phycobiliprotein C-phycocyanin of Arthospira platensis is used as a natural blue colorant in certain food products. The thermoacidophilic red microalga Cyanidioschyzon merolae might provide an alternative source of phycocyanin. Cyanidioschyzon merolae belongs to the order Cyanidiophyceae of the phylum Rhodophyta. Its natural habitat are sulfuric hot springs and geysers found near volcanic areas in, e.g., Yellowstone National Park in the USA and in Java, Indonesia. It grows optimally at a pH between 0.5 and 3.0 and at temperatures up to 56 °C. The low pH at which C. merolae grows minimizes the risk of microbial contamination and could limit production loss. As C. merolae lacks a cell wall, phycocyanin with a high purity number of 9.9 could be extracted by an osmotic shock using a simple ultrapure water extraction followed by centrifugation. The denaturation midpoint at pH 5 was 83 °C, being considerably higher than the A. platensis phycocyanin (65 °C). The C. merolae phycocyanin was relatively stable at pH 4 and 5 up to 80 °C. The high thermostability at slightly acidic pH makes the C. merolae phycocyanin an interesting alternative to A. platensis phycocyanin as a natural blue food colorant.


Cyanidioschyzon merolae; Food colorant; Phycocyanin; Pigments; Red microalga

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