Abstract:Cellulase was adopted to modify the millet bran dietary fiber. With soluble dietary fiber（SDF）yield as the index，modified conditions were optimized by the single factor test and orthogonal test. Then，the dietary fiber's water holding capacity，oil holding capacity，expansion force as well as in vitro cholesterol sorption capacity，and nitrite ions clearance rate were studied respectively both before and after the treatment. The results showed that the highest yield of soluble dietary fiber was 24.77% with the addition of 4.5% cellulase，9 h reaction time，and 60 °C reaction temperature. The cellulase modified-millet bran total dietary fiber（CM-MBTDF）enjoyed better oil holding capacity of 2.750 g/g and 3.440 g/g at 25 °C and 37 °C respectively，which were 2.3 and 2.9 times the capacity of millet bran dietary fiber （MBTDF）. However，after modification，the water holding capacity and expansion force decreased significantly. In addition，in vitro cholesterol absorption capacity was significantly increased. The absorption amount were 23.68 μmol/L and 22.28 μmol/L at pH2.0 and pH7.0 respectively，which were 1.31 and 1.96 times that of MBTDF. Both MBTDF and CM-MBTDF showed high nitrite ions clearance rate at pH2.0. CM-MBTDF could accelerate the nitrite ions clearance rate，and CM-MBTDF could significantly increase the rate at pH7.0.