Abstract: Preparation of soluble dietary fiber (SDF) from the peel of Rhizoma Dioscoreae by cellulase hydrolysis was studied.In order to optimize conditions,conventional single factor method was designed and the outcomes were as follows:solid/liquid ratio of 1:30,the dosage of cellulose of 4 U/mL,extraction time of 2 h,extraction temperature of 50 ^oC and alcohol precipitation time of 4 h,respectively.For further enhance the amount of soluble fiber,response surface analysis method was carried out.The conditions were further optimized as:solid/liquid ratio of 1:35,the dosage of cellulase of 5 U/mL,extraction temperature of 48 ^oC.Under these conditions,the yield of SDF was 22.87%,which was 3 times of the initial yield of 7.96%.In addition,the properties of the resulting SDF were also investigated.The water holding capacity and swelling capacity were 10.74 g/g and 6.45 mL/g,respectively.

Key words: peel of Rhizoma Dioscoreae, soluble dietary fiber, enzymatic hydrolysis, response surface methodology