2.2. Extraction and Determination of Total Phenolic Compounds The extraction of phenolic compounds was based on a previously reported method, with slight modifications [23]. Three grams of Spirulina and Chlorella were ho- mogenised with 75 mL of methanol or ethanol in an or- bital shaker at 35˚C for 120 min at 230 rpm. After cen- trifugation at 3220 g for 15 min, the supernatant was evaporated in a rotary evaporator at 50˚C. The extract was dissolved in 50 mL of distilled water, and the non- phenolics were precipitated with Ba(OH)2 and ZnSO4. The extract was then filtered through 0.45 µmfilter paper, and the volume was adjusted to 100 ml in volumetric flask with distilled water. The phenolic compounds (PC) in the extract were determined via spectrophotometry using the Folin-Ciocalteu reagent and a calibration curve of gallic acid at concentrations of 10 to 100 µg/ml [24]. The PC values in the samples were expressodas mg of gallic acid per gram of microalgae. The extracts were then frozen at −80˚C for 24 h in an ultrafreezer for sub- sequent lyophilization.