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PORPHYRA HAITANENSIS CHANG ET ZHENG: OPTIMIZATION OF POLYSACCHARIDE EXTRACTION BY RSM AND ITS ANTI-OXIDANT ACTIVITY

Response surface methodology (RSM) was used to investigate the optimum conditions for extracting polysaccharides from Porphyra haitanensis Chang et Zheng. Results indicated that a ratio of water to raw material of 60 ml/g, pH 8.0 and a microwave-assisted processing time of 5 min at 90 o C. Under the conditions the yield was 16.38 ± 0.12% (n = 5), the value within close range of predicted yield value. Moreover, the polysaccharide, at a concentration of 8 mg/ml, showed significant antioxidant activity in vitro, where scavenging activity of hydroxyl radicals (OH), superoxide anions (•O2 - ) and DPPH free radicals were 33.81, 51.78 and 31.67%, respectively.