Efficient extraction of Spirulina phycocyanin using natural deep eutectic solvents and its characteristics

Abstract

Phycocyanin is the main natural pigment in Spirulina. Here we used an eco-friendly method based on natural deep eutectic solvent (NADES) and ultrasound-assisted extraction to extract phycocyanin. Nine different hydrophilic NADES species were explored for the recovery of phycocyanin from Spirulina dry biomass. NADES [glycerol/glucose (molar ratio = 3:1), Gly/Glu₂] was selected for optimization of extraction conditions (sonication time, sonication power, liquid-to-solid ratio, water content) by response surface methodology. Under optimal extraction conditions, extraction yield of 67.86 mg/g was obtained with obvious improvement compared with the initial extraction yield of 48.36 mg/g. Further comparison of antioxidant activities was performed between NADES extract and water extract. NADES extract also showed strong antioxidant activities. The stability of phycocyanin was significantly improved by NADES compared with water extract. In conclusion, our study used sonic dismembrator with very short time of 5 min, dried Spirulina biomass prepared by spray drying as raw material with better adaptability for industrial production, and more appropriate NADES species Gly/Glu₂ for extraction. After optimization, phycocyanin yield increased by 40.32 %. In addition, NADES extract (phycocyanin) had relatively strong antioxidant activities and strong stability at 30 d, which was very conductive to storage of phycocyanin. Therefore, our study had some advantages compared with previous studies. This study provided a promising method for phycocyanin extraction with high efficiency using an economical and eco-friendly extraction solvent, which was very important for the application in cosmetic industry.