Enhancement of Phycocyanin Extraction from Dry <i>Spirulina platensis</i> Powder by Freezing-Thawing Pre-treatment

Phycocyanin (PC) is a bioactive compound that can function as an antioxidant, anti-inflammatory, immunomodulatory, and anti-cancer agent. It can act as a potential material in preventing COVID-19 and curing those suffering from it. Spirulina platensis (SP) is one of the microalgae rich in proteins and PC. This study aimed to determine the optimum PC extraction from SP, using distilled water as solvent through freezing-thawing pre- treatment. The variables set in the investigation were water content in SP before freezing (24.7-84.9 % wet basis), soaking time (0.25, 1, 2, and 6 hours), raw materials' storage period (1-13 months), freezing time (1-141 days), and the (solvent/biomass) ratio (20-440 mL/g). Spirulina platensis powder was soaked, frozen, thawed, and extracted in batch operation. The residue was extracted with the same solvent. The PC concentration in the filtrate was determined by measuring its absorbance using a spectrophotometer at wavelengths 615 and 652 nm. The experiment gave the optimum yield