Abstract: Using olive pomace as the raw material, the alkali method was adopted to extract soluble dietary fiber (SDF) and insoluble dietary fiber (IDF), and its physicochemical properties were also studied. The extraction conditions of IDF and SDF were optimized through orthogonal test based on single factor test. The results showed that the optimum extraction conditions were concentration of NaOH 8%, the extraction temperature of 80℃, the extraction time 80 min, and liquid-solid ratio of 15:1(mL:g). Under this conditions, the yields of SDF and IDF were 28.74% and 52.39%, respectively. The results of physicochemical properties showed that the water holding capacity,swelling capacity and oil holding capacity of IDF were 3.38 g/g, 2.20 mL/g, 1.91 g/g, respectively. The water holding capacity, swelling capacity and oil holding capacity of SDF were 5.05g/g, 4.78 mL/g and 4.25 g/g, respectively. The glucose dialysis retardation index of SDF, IDF and defatted pomace were 13.22%,8.55% and 4.38%, respectively, by the dialysis for 90 min. The results of scanning electron microscope showed that IDF had looser morphology and more cavities and cracks, and SDF had smaller particle size and more cavities after alkali extraction.

Key words: olive pomace, dietary fiber, alkali method, extraction, physicochemical properties