Ultrasound-assisted extraction of phenolics from Spirulina platensis by different solvents: An optimization study based on simplex lattice mixture design

Spirulina has attracted attention in recent years because it is an important source of bioactive compounds such as phenolics. In this study, different solvents (acetone, ethanol, and distilled water) were evaluated in terms of their phenolic extraction performance from Spirulina platensis which is a popular functional nutraceutical. This was accomplished by performing optimization research and using the simplex lattice mixture design approach to identify the optimal solvent type or solvent mixture that may provide the highest phenolic yield. Fifteen extracts were prepared, and their total phenolic content was determined. After the data had been modeled, it was concluded that the solvent with the highest phenolic recovery performance was distilled water. Alone the water could extract more phenolics than acetone and ethanol or their mixtures at different ratios. Total phenolic contents of acetone, ethanol, and distilled water extracts were 9.26, 11.82, and 36.51 mg GAE/g samples showing that the water was the best. Having established water as the optimal solvent for S. platensis extraction, we investigated the influence of various pH conditions (3, 5, 7, and 9) on both conventional hot water extraction and ultrasound-assisted extraction methods. Results showed that higher pH values significantly increased total phenolic content, and ultrasound extraction yielded better results than traditional hot water extraction.