Recovery of phycocyanin from microalgae Spirulina using membrane technology and evaluation of its antioxidant activity

Phycocyanin (PC) is a blue-colored natural pigment extracted from microalgae Spirulina and exhibits several bioactivities, including antioxidant, anti-inflammatory, hepatoprotective, and neuroprotective effects. This pigment has been applied as a natural colorant in food, nutraceutical, cosmetic, and biotechnology industries. The extraction and purification of phycocyanin from Spirulina typically involves combining different techniques. Membrane technology has gained broad interest in the processing of biomolecules and liquids. This technique is practical, easy to scale up, and used at ambient temperature, minimizing thermal damage to the product. This study investigates the recovery of phycocyanin through aqueous extraction and microfiltration (MF) process and evaluates its antioxidant activity. The crude extract was passed through a Dead End Stirred Microfiltration Cell (DESMF) with a pore size of 0.15 µm. The MF system was operated at various transmembrane pressure of 20, 30, and 40 psia with a constant rotation speed of 400 rpm. Samples were collected during MF process as permeate and retentate. The results showed that the microfiltration process on Spirulina extracts increased phycocyanin (PC) concentration and free radical inhibition. Most phycocyanins were retained in the MF retentate. The microfiltration processing at a transmembrane pressure of 40 psia has resulted in an optimum phycocyanin concentration of 0.48 mg/mL in the retentate. In addition, total solids, dissolved protein, and total phenolic content in MF retentate at optimum conditions were 2.02%, 4.24 mg/mL, and 6,40 mg/mL, respectively. The crude extract of phycocyanin exhibited free radical inhibition (74.55%) with a significant increase under the microfiltration process (96.84%), thereby improving the antioxidant activity of phycocyanin in the retentate fraction.