Abstract: In this experiment, wheat bran was ground and suspended in distilled water before being treated by high hydrostatic pressure (HHP) in an effort to explore the effects of pressure, holding time, particle size, and wheat bran concentration on functional properties of wheat bran, and the ultrastructure and functional groups of wheat bran before and after modification were analyzed by scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. Under the conditions of pressure 400 MPa, holding time 20 min, particle size 40 meshes, and wheat bran concentration 20%, modified wheat bran had the highest soluble dietary fiber (SDF) content and cation exchange capacity and the lowest lipase activity. Under the conditions of pressure 400 MPa, holding time 15 min, particle size 50 meshes, and wheat bran concentration 20%, the water-holding capacity and oil-holding capacity were higher. Under the conditions of pressure 300 MPa, holding time 25 min, particle size 40 meshes, and wheat bran concentration 15%, the nitrite scavenging ability was stronger. Under the conditions of pressure 500 MPa, holding time 25 min, particle size 50 meshes, and wheat bran concentration 25%, the cholesterol adsorption capacity was stronger. SEM results showed that HHP destroyed the structure of dietary fiber in wheat bran and made its structure loose. FTIR measurement confirmed that HHP could destroy intermolecular covalent bonds and consequently degrade cellulose and convert insoluble dietary fiber (IDF) to SDF. The modified wheat bran has good functional properties and is promising in the future.

Key words: high hydrostatic pressure, wheat bran, oil-holding capacity, cholesterol adsorption capacity, lipase activity, 1,1-diphenyl-2-picrylhydrazyl radical scavenging capacity