Impact of pressurized liquid extraction and pH on protein yield, changes in molecular size distribution and antioxidant compounds recovery from Spirulina.

The research aims to extract nutrients and bioactive compounds from Spirulina using a non-toxic, environmentally friendly and efficient method-Pressurized Liquid Extraction (PLE). In this work, Response Surface Methodology (RSM)-Central Composite Design (CCD) was used to evaluate and optimize the extraction time (5-15 min), temperature (20-60°C) and pH (4-10) during PLE extraction (103.4 bars). The multi-factor optimization results of the RSM-CCD showed that under the pressure of 103.4 bars, the optimal conditions to recover the highest content of bioactive compounds were 10 min, 40°C and pH 4. Furthermore, the compounds and antioxidant capacity of PLE and non-pressurized extraction extracts were compared. The results showed that under the optimal extraction conditions (10 min, 40°C and pH 4), PLE significantly improved the antioxidant capacity (2870.5±153.6 µM TE), protein yield (46.8±3.1%), chlorophyll a (1.46±0.04 mg/g), carotenoids (0.12±0.01 mg/g), total polyphenols (11.49±0.04 mg/g) and carbohydrates content (78.42±1.40 mg/g) of the extracts compared with non-pressurized extraction...