Abstract: The water-holding capacity, oil-holding capacity, cation exchange capacity and cholesterol adsorption capacity of dietary fiber from tillering onion with different particle sizes were studied and the structure was determined by scanning electron microscopy (SEM), infrared spectroscopy and X-ray diffraction analysis. The results showed that the soluble dietary fiber content of tillering onion was 5.79%. The water-holding capacity, oil-holding capacity, swelling capacity and the cation exchange capacity of the dietary fiber were 14.83 g/g, 19.57 mL/g, 1.95 g/g and 0.62 mmol/g, respectively. The cholesterol adsorption capacity was 126.73 mg/g at pH 2, and 159.50 mg/g at pH 7. Under SEM, the dietary fiber exhibited an irregular fluffy network structure. Fourier transform infrared spectroscopy analysis suggested that the dietary fiber had the characteristic absorption peaks of cellulose and hemicelluloses, such as C＝O, O—H, C—H. The results of X-ray diffraction indicated that the crystallinity of the dietary fiber was better and the crystalline and amorphous regions were preserved.

Key words: tillering onion, dietary fiber, structure, properties