Abstract:

The phosphate modification of insoluble dietary fiber (IDF) from soybean dregs was optimized by single factor and orthogonal array design methods for maximizing its water-binding capacity (WBC). Meanwhile, the structure of modified soybean IDF was observed using X-ray diffraction and scanning electron microscopy. It was found that the optimum conditions for soybean IDF modification were as follows: disodium hydrogen phosphate concentration 0.1 g/100 mL, material/liquid ratio 1:60 (g/mL) and modification temperature 50 ℃ for a modification duration of 1 h and that the WBC of modified soybean IDF under these optimum conditions was up to 11.95 g/g. After phosphate modification, the structure of soybean IDF was improved partially and the surface became slightly wrinkled and loose and displayed distinct sheeting structure. What’s more, an evenly distributed honeycomb-like surface structure of modified soybean IDF granules was observed. The X-ray diffraction pattern of modified soybean IDF showed a remarkable intensity peak at 34.76 ℃, with a crystallinity of 30.57%.

Key words: soybean dregs, dietary fiber, solubility, modification, process optimization, structural features