Abstract: Soluble dietary fiber (SDF), insoluble dietary fiber (IDF) and total dietary fiber (TDF) were prepared from Rosa roxburghii Tratt. pomace by enzymatic hydrolysis using α-amlyase. Dynamic high pressure microfluidization (DHPM) was used to modify SDF, yielding DHPM-SDF. The physicochemical properties of IDF, SDF and DHPM-SDF, as well as their inhibitory effects on glucose diffusion and α-amylase activity were studied. It was shown that both IDF and SDF slowed down the glucose flow process by absorbing glucose and inhibiting its diffusion, and reduced starch digestibility by altering the secondary structure of pancreatic amylase. The ability of IDF to adsorb glucose and inhibit glucose diffusion was 1.28 and 1.99 times higher than that of SDF, respectively. However, the inhibitory effect of SDF against pancreatic amylase was 1.73 times higher than that of IDF, and SDF exerted its inhibitory effect mainly through changing the α-helix and random coil conformations of pancreatic amylase. The ability of TDF to adsorb glucose and inhibit amylase activity were similar to those of IDF. The average particle size of DHPM-SDF was 2.08-fold higher than that of SDF, so that the ability to adsorb glucose and inhibit glucose diffusion were increased by 28.13% and 62.09%, respectively. In addition, DHPM-SDF significantly reduced the α-helix and random coil conformations of pancreatic amylase (P < 0.05), its amylase inhibitory activity is 1.44 times higher than that of SDF. In conclusion, dietary fibers from Rosa roxburghii Tratt. pomace, especially soluble dietary fiber, can be used as a good resource for the development of hypoglycemic products, and DHPM is an effective modification method to improve the hypoglycemic activity of SDF from Rosa roxburghii Tratt. pomace.

Key words: Rosa roxburghii Tratt. pomace; dietary fiber; dynamic high pressure microfluidization; starch digestibility; glucose diffusion