[Modified method for obtaining phycocyanine concentrate of Arthrospira platensis biomass]

The biomass of Arthrospira platensis cyanobacteria is a source of bioactive compounds such as chlorophylls, carotenoids, and, particularly, phycobiliproteins: C-phycocyanin and allophycocyanin. The wide range of biological activity shown by extracts with a high content of phycocyanins determines the prospects for their use as dietary supplements and ingredients of special foods. For food purposes, the degree of purity of phycocyanin concentrates, determined by the ratio of optical densities of their aqueous solutions at two wavelengths, namely D₆₂₀/D₂₈₀, must be greater than 0.7. Most methods for obtaining phycocyanin concentrates include laborious steps of fractional ammonium sulphate precipitation of protein from A. platensis biomass extracts followed by removal of salts solution. The use of membrane technology, specifically microfiltration, makes it possible to significantly intensify and simplify the process of obtaining phycocyanin concentrates. The aim of this research was to modify the method for obtaining a high-purity A. platensis phycocyanin concentrate by replacing the stage of ammonium sulfate precipitation of the protein by ultrafiltration of the extract followed by microfiltration. Material and methods. A sample of dry A. platensis biomass was used as a feedstock. Extraction of A. platensis biomass was carried out at a temperature of +40 °C for 3 h, the resulting suspension was centrifuged, and the supernatant was separated from the sediment. The obtained extract was subjected to ultrafiltration (membrane with a pore diameter of 30 kDa) followed by removal of the permeate containing low molecular weight impurities. The retentate was subjected to microfiltration (membrane with a pore size of 0.2 μm), concentrated by reverse osmosis and freeze-dried. Results. The content of C-phycocyanin and allophycocyanin in the dry concentrate was 42.0±1.3 and 7.0±0.3%, respectively, the degree of purity was 1.98. Conclusion. The scheme for obtaining A. platensis phycocyanin concentrate has been modified. A concentrate was obtained with a high degree of purity, allowing its use in food.