Abstract: This study was conducted to optimize enzyme-assisted extraction conditions for wheat bran polysaccharides using response surface methodology and subsequently investigated prebiotic properties and antioxidant activity of this product in vitro.A Box-Behnken design was carried out for the optimization of enzyme addition level,extraction temperature,extraction time and solid-liquid ratio.The reducing force and DPPH and ·OH radical scavenging ability of fermented wheat bran polysaccharide was compared with wheat bran polysaccharide.The effects of fermented wheat bran polysaccharide on Lactobacillus acidophilus,Lactobacillus plantarum and Bifidobacterium bifidum was also compared with wheat bran polysaccharide.Optimum enzyme-assisted extraction conditions for production of wheat bran polysaccharides were:enzyme addition level,1 000 U/g;extraction time,60 min;solid-liquid ratio,1∶16.The ultimate wheat bran polysaccharides yield using the optimized enzyme-assisted extraction conditions reached 73.35%.The results demonstrate that the obtained wheat bran polysaccharides could scavenge DPPH and ·OH radical and promote the proliferation of Lactobacillus acidophilus,Lactobacillus plantarum and Bifidobacterium bifidum.

Key words: fermented wheat bran polysaccharides, response surface, enzymatic extraction, antioxidant activity, prebiotic properties