Study On The Submicron Wheat Bran Insoluble Dietary Fiber

In this paper we got the submicron dietary fiber powder by the processes of coarse comminute, freeze ultrafine grinding and high-energy nano ball milling and the average particle size of powder was 343.5nm and this was a great improvement as compared to current reports. Compared with dietary fiber before and after grinding, nanonized insoluble dietary fiber was changed in composition, physicochemical properties and functional properties. The main results were as follows.As particle size decrease, the contents of protein, fat, starch and ash were increased. Meanwhile a redistribution of fiber components from insoluble to soluble fractions was observed.The physicochemical properties were changed after gringding. Compared with crude powder, water holding capacity; water retention capacity, swelling capacity and oil holding capacity were decreased; water soluble index was increased; vicosity was decreased with particle size decreased while increased with solution concentration increased; the color was increased; the liquidity of nonization DF powder was deterioration; bulk density was increased.The functional properties were also altered after grinding. Compared with crude powder, the adsorption capacity of cholesterol was decreased; the adsorption capacity of Cd²⁺ and Pb²⁺ were decreased; the scavenging towards NO2- was decreased; the cation exchange capacity of DF was decreased. Furthermore, the antioxidant activity of dietary fibe before and after grinding was studied. Compared with dietary fiber before grinding, nanonized insoluble dietary fiber was improved the abilities in chelating activity, reducing power and TPC whereas decreased in DPPH radical scavenging activity.The picture of X-ray diffraction revealed that nanonization could not change the crystal structure of DF. And the infrared spectroscopy of DF also indicated that nanonization could not alter the molecular structure.Dietary fiber juice was made by adding submicron DF powder in the juice solution and the stability of the mixed solution was studied. It is found that the submicron DF juice were better than both DF before grinding and superfine gringding DF in taste, colour and appearance.