Abstract: Dietary fiber (DF) containing 8.2% soluble dietary fiber (SDF) extracted from Flammulina velutipes was modified by cellulase or high-temperature cooking. As determined using one-factor-at-a-time and orthogonal array designs, the optimal processing parameters for the cellulase method were as follows: liquid-to-material ratio 35:1, enzyme dosage 1.5%, and hydrolysis time 2 h, giving an SDF yield of 16.2%. The optimal processing parameters for the high-temperature cooking method were liquid-to-material ratio 30:1, temperature 125 ℃, and time 50 min, providing an SDF yield of 20.4%. The cation exchange capacity, cholesterol adsorption capacity, and glucose absorption capacity of the modified DFs were compared with those of the unmodified one, and further comparative analyses were performed using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy. It was found that the autoclaved DF was better than the cellulase-treated DF in general. Furthermore, mice with obesity induced by a high-fat diet were intervened with the autoclaved DF. Body mass, as well as triglycerides (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) in serum were measured. It was found that the autoclaved DF could improve the physiological indexes of obese mice, indicating its good bioactivity.

Key words: dietary fiber; modification; physicochemical properties; physiological activity