Abstract: In this study,a novel method for purifying acidic polysaccharides from Lycium barbarum by foam separation was established.Based on the single factor experiment, Box-Behnken design in Design-Expert software was adopted to investigate the influence of three factors:dilution times (n),superficial gas floating rate (G) and floating time (t),on enrichment ratio and recovery of acidic polysaccharides.The regression equation showed that under the optimized conditions,when dilution times (n) was 10,superficial gas floating rate (G) was 207 mL/min,floating time (t) was 62 min,enrichment ratio and recovery of acidic polysaccharides reached highest to 3.61 and 81.76%.The relative error between verification values (3.81% and 82.47%) and theoretic values were 5.5% and 0.87%,respectively.

Key words: Lycium barbarum polysaccharides, alduronic acid, foam separation, response surface methodology