Phycocyanin (PC) is a protein that belongs to the family of phycobiliproteins which are the photosynthetic accessory pigments in cyanobacteria and certain red algae. It is obtained by extraction from Arthrospira platensis.

On the market, the protein is mainly marketed in liquid form packaged in ampoules or vials.

Phyco-Biotech laboratories provide phycocyanin in powder form obtained after lyophilisation. This form has many advantages over the liquid form. These advantages can be identified with comparative spectrophotometric absorption curves of each form (between 240 and 750nm), liquid or solid, dissolved in water.

phycocyanine pure



The quality and purity of phycocyanin in solution are obtained by measuring the ratio of absorption at approximately 616nm to absorption at approximately 280nm.

  • 616nm : maximum absorption wavelength of phycocyanin.
  • 280 nm : maximum absorption wavelength of interfering compounds.

The higher the ratio, the purer the phycocyanin. (See the comparative purity indices in the table at the end of the article).


Phycocyanin concentration is obtained with the following calculation formula (Bennet and Bogorad – 1973):

A620nm – (A650nm x0,474) / 5,34  * volume of solution = quantity of PC in milligrams


Below are the absorption spectra with the changes over time, for two competing phycocyanins packaged in ampoules compared to Phyco-Biotech lyophilised phycocyanin in solution in water.

These spectra were obtained using the supernatants obtained after the ampoules were centrifuged. Exactly the same batches were analysed over time. The “Ampoule A”, “Ampoule B” and Phyco-biotech phycocyanin powder batches were stored at room temperature and protected from light, as recommended on the packaging.

In lyophilised form, the absence of water prevents the occurrence of oxidative phenomena which degrade blue protein. Therefore, phycocyanin can be preserved for several years. However, in the liquid form, it is degraded in a few months by oxidation reactions. This oxidation is quite clearly visible in ampoules where a large deposit forms, accompanied by significant fading of the characteristic blue colour of the protein.

Through our extraction and purification processes we are able to provide the purest phycocyanin on the market.

The comparative table below is based on the calculation of Phycocyanin concentration and purity. The table is based on data from absorption spectra (UV-Visible Spectrophotometry).

phycocyanine purity comparison


The values presented in the table show that:

    1. Liquid PC in ampoules degrades very quickly.
    2. In both batches of ampoules, the quantity of interfering compounds is saturating and increases over time.
    3. For Phyco-Biotech, absorption at 280nm is very low and simply concerns phycocyanin proteins.
    4. The purity ratios confirm these observations. The ratio is very low for solutions in ampoules (<0.1%). However, it is much higher for Phyco-biotech powdered protein: 3.67 in 2017 and 3.22 in 2019. As a reference value, pure phycocyanin has a purity ratio of 4.3.
    5. In the “Ampoule A” sample, the measurement shows only a very small fraction of the amount of phycocyanin mentioned on the product packaging in 2018 (5.21%). The 2019 measurement shows that there is almost no more phycocyanin (1.04%).
    6. In the “Ampoule B” sample, the assay shows that there is already less phycocyanin than the amount mentioned on the product packaging in 2017 (74.3%). The 2019 measurement shows that the amount of phycocyanin measured is only 14.6% of the amount claimed on the packaging.
    7. The percentage of phycocyanin in the powder produced by Phyco-Biotech was 92% in 2017 and decreased very slightly to stabilize at 85.1% in 2019.
    8. The comparative photos of the tubes containing the centrifuged solutions of the three samples speak for themselves. The characteristic blue colour has disappeared from the 2 samples, “Ampoule A” and “Ampoule B” compared to the powdered solution by Phyco-Biotech.
comparaison couleur phycocyanine ampoule