Pilot-scale concentration and partial purification of food-grade phycocyanin from Arthrospira platensis via cross flow filtration: From biomass to final product

From food- to analytical-grade products, the commercial exploitation of phycocyanin (PC) strongly depends on its degree of purity. In this study, we utilized a pilot-scale system (100 L working volume), based on serial tangential flow micro- and ultra-filtration (cut size 0.2 μm and 50 kDa, respectively) for the concentration and purification of PC extracted from a commercial strain of Arthrospira platensis. The process resulted in a PC recovery of around 54%, whilst the resulting solution had a concentration of 1.1 ± 0.2 mgPC mL−1, purity of 1 ± 0.2, and antioxidant activity of 84 ± 6 ppmascorbic-acid-equivalent. Various preservatives were evaluated in order to enhance the stability of aqueous PC solution at room temperature. The addition of 0.4% citric acid had no effect (half-life ~ 7 days), while the addition of 2.5% sodium chloride or 20% sucrose significantly increased half-life up to ~ 250 days. PC solutions underwent either spray- or freeze-drying, either with or without carrier (trehalose) addition. The obtained PC powders had up to twofold higher color values compared to a commercial sample. The spray-drying process negatively affected the purity and yield of the final product (10% and 50% less than freeze-drying, respectively). In summary, our results suggest that tangential flow filtration followed by freeze-drying has huge potential for the production of food-grade phycocyanin.