Extraction of antioxidants from Chlorella sp. using subcritical water treatment

Chlorella sp. microalgae is one of the main source of natural bioactive compounds used in the food and pharmaceutical industries. Subcritical water extraction is the technique that offers an efficient, non-toxic, and environmental-friendly method to obtain natural ingredients. In this work, the extracts of Chlorella sp. microalgae was evaluated in terms of: chemical composition, extraction (polysaccharides) yield and antioxidant activity, using subcritical water extraction. Extractions were performed at temperatures ranging from 100 degrees C to 300 degrees C. The results show that by using subcritical water, the highest yield of polysaccharides is 23.6% that obtained at 150 degrees C. Analysis on the polysaccharides yield show that the contents were highly influenced by the extraction temperature. The individual antioxidant activity were evaluated by in vitro assay using a free radical method. In general, the antioxidant activity of the extracts obtained at different water temperatures was high, with values of 31.08-54.29%. The results indicated that extraction by subcritical water was effective and Chlorella sp. can be a useful source of natural antioxidants.