Polysaccharide extraction from Spirulina sp. and its antioxidant capacity

•Optimum conditions for polysaccharide extracts was a ratio of 1:45, 90°C for 120min.•Polysaccharide extracts from Spirulina at 90°C contained high phenolic content.•Rhamnose is the major sugar component of polysaccharide extracts from Spirulina. To optimize polysaccharide extraction from Spirulina sp., the effect of solid-to-liquid ratio, extraction temperature and time were investigated using Box–Behnken experimental design and response surface methodology. The results showed that extraction temperature and solid-to-liquid ratio had a significant impact on the yield of polysaccharides. A polysaccharides yield of around 8.3% dry weight was obtained under the following optimized conditions: solid-to-liquid ratio of 1:45, temperature of 90°C, and time of 120min. The polysaccharide extracts contained rhamnose, which accounted for 53% of the total sugars, with a phenolic content of 45mg GAE/g sample.