Abstract: Water soluble dietary fiber (S-CDF), water insoluble dietary fiber (I-CDF)(acid insoluble dietary fiber (ACI-CDF) and alkaline insoluble fiber (ALI-CDF)) were extracted from high-temperature-high-pressure-extruded corn spermoderm. Solubility and physical properties of each of these CDFs and mixtures at different ratios of S-CDF to I-CDF were analyzed before and after high-temperature-high-pressure extrusion. The results showed that extrusion at 165 ℃, a material-to-liquid ratio of 1:1.5 and a feed speed of 15 kg/h proved optimal. Under these extrusion conditions, the extraction yield of S-CDF was increased by 68.74%, the expansibility, water-holding capacity and solubility of S-CDF, I-CDF, ACI-CDF and ALI-CDF were distinctly increased. When expansibility, cation exchange capacity, water-holding capacity, oil-holding capacity and water-binding capacity were comprehensively considered, the optimal S-CDF to I-CDF ratio was 1:4.

Key words: corn spermoderm, dietary fiber, solubility, physical properties