Optimization of Extraction Parameters and Effect of Different Solvent Systems on The Omega-3 Fatty Acids Content of Algal Oil (Nannochloropsis sp.)

Abstract

Ultrasonically-assisted algal oil (Nannocholoropsis sp.) extraction (UAE) was optimized using Response Surface Methodology (RSM) and hexane. Extraction variables were determined as extraction time, temperature, and solvent:biomass ratio. Optimization was made by aiming both maximum oil yield and omega-3 fatty acid (ω-3 FA) content at the same time. The optimum conditions were determined to be 44.30 ℃, 62.46 min, 19.9:1 g/ml. The extraction time and temperature significantly affected the yield and ω-3 FA content, whereas solvent: biomass ratio did not affect the range of values tested for each of the variables(p<0.05). Then, under these optimum conditions, UAE was applied using selected solvents of different polarities (hexane, chloroform, methanol, ethanol and 2-propanol). The effects of different solvents on the oil yield, ω-3 FA content, oxidation, and nutritional properties of algal oil were investigated. Methanol was found to be more efficient than other solvents considering oil yield and ω-3 FA, especially eicosapentaenoic acid (EPA) content (14.46%). Although methanol and chloroform are widely used in extraction, their toxicity limits their use in the food industry. Considering the oil yield and ω-3 FA content of non-toxic solvents, it was determined that 2-propanol was more preferable due to its high ω-3 FA content.