Objective: To optimize extraction and purification procedures of antioxidant activity polysaccharides from Brassica rapa. Method: With the crude polysaccharides yield

the content and antioxidant activity of total polysaccharides as indicators

orthogonal design was used to optimize extraction technology by taking extraction times

solid-liquid ratio and extraction time as factors;With the removal rate of pigment and the loss rate of polysaccharides as comprehensive evaluation index

effects of bleaching temperature

adsorption time and activated carbon dosage on decoloration technology were investigated by orthogonal test. Result: Optimum extraction technology was as following:solid-liquid ratio 1:30

extracted 3 times at 90 ℃ with 2 h each time;The best decoloration technology was:absorbed 40 min with 3% activated carbon at 60 ℃.Under these conditions

purity of polysaccharides from B. rapa was up to 4.66%

the IC50 value of DPPH free radical scavenging was 6.71 g·L-1. Conclusion: These optimized extraction and purification processes were stable and reliable

a high level of polysaccharides with fewer impurities was obtained

which indicated that optimized processes were suitable for industrial production of polysaccharides from B. rapa.Meanwhile

these results indicated that polysaccharides from B. rapa had strong antioxidant activity

and worthy of further study.