Effect of Solvent Type on Pigment Concentrations in Extracts of Spirulina sp.

Abstract

Spirulina sp. is a photosynthetic cyanobacterium with potential as a source of natural pigments, including chlorophyll and phycobiliproteins (phycocyanin, phycoerythrin, and allophycocyanin). This study aimed to determine the pigment content of Spirulina sp. extracted using five different solvents: ethanol, distilled water, NaHCO₃, KCl, and NaCl. Extraction was performed using the freeze-and-thawing method at -4°C for 24 hours, followed by centrifugation to obtain the supernatant for spectrophotometric analysis. The results showed that the highest phycocyanin and total phycobiliprotein contents were obtained using NaCl (5.98 mg/mL and 8.08 mg/mL, respectively), while the lowest was obtained using ethanol (0.28 mg/mL phycocyanin). Conversely, ethanol produced the highest chlorophyll-a (553.09 mg/L) and allophycocyanin (5.70 mg/mL) contents, far exceeding the other water-based solvents. Phycoerythrin content was relatively uniform across all solvents (0.28–0.34 mg/mL), Visual color differences among the extracts corroborated the quantitative results, with ethanol extracts appearing green (chlorophyll-dominated) and water/salt-based extracts appearing blue (phycocyanin-dominated). These findings indicate that solvent type strongly influences the type and amount of pigment extracted from Spirulina sp., suggesting that solvent selection should be tailored to the target pigment salt solutions such as NaCl are recommended for optimal phycocyanin recovery, while ethanol is more suitable for chlorophyll-a recovery.