Modification of insoluble dietary fiber from ginger residue through enzymatic treatments to improve its bioactive properties

To add value ginger residues containing insoluble dietary fiber (IDF), multiple enzymes were used to obtain modified insoluble dietary fiber (MIDF). The water retention capacity (WRC), water swelling capacity (WSC) and oil binding capacity (OBC) for lard of MIDF were 22.45%, 33.85% and 36.26% higher than those of IDF, respectively. Meanwhile, MIDF showed higher cation exchange capacity (CEC) than that of IDF. Cholesterol, sodium cholate and sodium nitrite binding capacity (CBC, SCBC, SNBC) of MIDF were 70.28%, 42.07% and 15.9% higher than those of IDF at pH 7, respectively. And CBC and SNBC were 21.18% and 12.17% higher than those of IDF at pH 2, respectively. Compared to IDF, MIDF exposed more hydrophilic groups and more specific surface areas. The oral administration showed that MIDF significantly reduced total cholesterol (TC), triglyceride (TG) and atherogenic index (AI) by 12.23%, 25.15% and 60.63%, respectively (P < 0.05), but significantly increased the high density lipoprotein-cholesterol (HDL-C) by 32.93% to the normal level (P < 0.05). Furthermore, histopathology of liver also indicated that MIDF could reduce the risk of fatty liver. These properties demonstrated that MIDF showed better physicochemical and functional properties than IDF. Thus MIDF would be a potentially available food ingredient in weight-loss functional food processing.