Abstract: Super micro-milling soybean dietary fiber was studied with wet processing or vacuum freeze-drying on physical properties (involving average evaporation rate of water, swelling power, water-holding power and water binding power) of the dietary fiber. At the same time, the same physical properties after the super micro-milling with dry processing were also studied. The results showed that the average evaporation rate of water, swelling power, water-holding power and water binding power respectively increase to 0.475 g/min, 9.02 ml/g, 13.50 g/g, 25.00 g/g from 0.188 g/min, 5.89 ml/g, 5.42 g/g, 12.55 g/g. The average granularity is within 200nm after being dealt with the superfine grinding by wet processing. While the average evaporation rate of water, swelling power, water-holding power and water binding power after superfine grinding by the dry processing increase to 0.562 g/min, 8.13 ml/g, 12.06 g/g, 24.45 g/g respectively, the average granularity is within 200～300 nm. The conclusion is that the effects on improving swelling power, water-holding power and water binding power dealt with superfine grinding by wet processing are greater than superfine grinding by dry processing. But the superfine grinding by dry processing could better help enhance the average water evaporation rate.

Key words: soybean dietary fiber, superfine grinding by wet processing, superfine grinding by dry processing, physical properties