Modifying the structure, emulsifying and rheological properties of water-soluble protein from chicken liver by low-frequency ultrasound treatment.

The influence of low-frequency ultrasound on the structure, emulsifying and rheological properties of water-soluble protein from chicken liver (CLWP) was investigated. CLWP solutions (10%, w/v) were treated by ultrasound for 4 min at a frequency of 20 kHz (UCLWP, amplitude 50% at an output 100 W, 11.5 W/cm2). The secondary and tertiary structure and thermal denaturation properties were changed in UCLWP. However, SDS-PAGE showed no changes in the subunit compositions between UCLWP and CLWP. Surface hydrophobicity and sulfhydryl groups of UCLWP increased demonstrating partial unfolding of water-soluble proteins and reduced its intermolecular interactions by ultrasound effect. UCLWP showed the smaller and more uniform particles with high-density holes. Furthermore, emulsifying activity index and emulsion stability index of UCLWP had a significant improvement over that of CLWP. UCLWP had lower shear stress and motion resistance during the rheological evaluation. These modifications of the structure, emulsifying and rheological properties for UCLWP could expand the application of chicken liver protein and increase the added value of chicken liver by-products.