Abstract: In order to improve the coarse taste of dietary fiber and enhance its characteristics, in the present study, Phyllostachys praecox dietary fiber (PPDF) from bamboo shoots was treated by heavy pressure grinding, jet milling and ordinary grinding, yielding three powders: Z-PPDF, M-PPDF and C-PPDF, respectively. Our aim was to explore the effects of different ultrafine grinding treatments on the structure, physicochemical properties of dietary fiber and on its ability to bind cholesterol, sodium cholate and nitrite. The results showed that compared with C-PPDF, the particle size of Z-PPDF and M-PPDF was significantly (P < 0 .05), reduced by 84.82% and 94.81%, respectively, and the specific surface area was increased by 5.92 and 8.38 folds, respectively. Fourier transform infrared spectra showed that the position of hydroxyl groups in Z-PPDF and M-PPDF moved in a small range with increased peak width and absorption intensity. The surface of Z-PPDF and M-PPDF was rough, and the thermal stability was enhanced. Nevertheless, there was no significant change in the composition or structure of PPDF. Compared with C-PPDF, the contents of soluble dietary fiber in Z-PPDF and M-PPDF increased by 25.23% and 38.59% (P < 0.05), respectively, resulting in an improvement in hydration properties. Z-PPDF and M-PPDF, especially the latter, had a significantly enhanced ability to bind cholesterol, sodium cholate and nitrite. This study indicated that jet milling could enhance functional properties of PPDF to the maximum extent.

Key words: ultrafine grinding, Phyllostachys praecox, dietary fiber, structure characterization, cholesterol binding force