Effect of high-pressure homogenization on structural changes and emulsifying properties of chicken liver proteins isolated by isoelectric solubilization/precipitation

Abstract

This study investigated the effect of high-pressure homogenization (HPH) (0, 20, 40 and 60 MPa) on the emulsifying properties and structural changes of chicken liver (CL) proteins isolated by isoelectric solubilization/precipitation (ISP) (with the acid/alkaline solubilization at pH 2.0, pH 3.0, pH 11.0 and pH 12.0 respectively and the precipitation at pH 5.5). Results showed that HPH could significantly decrease the particle size. With the increase of homogenization pressure, the solubility of the same ISP-isolated CL-proteins increased significantly and that of alkali-isolated proteins was the highest (P < 0.05). The preferable emulsifying activity index (EAI) and emulsifying stability index (ESI) were obtained at pH 11.0 after 40 MPa treatment (reaching 34.90 m2/g and 37.77% respectively), which appeared the highest creaming layer. Compared with other treatments, the corresponding same ISP-isolated CL-proteins at 40 MPa HPH had highest surface hydrophobicity index (H0) and free sulfhydryl content. After HPH, Raman spectroscopy revealed that the same ISP-isolated CL-proteins presented a decrease in α-helix accompanied by the increase of the β-sheet to be beneficial to the formation of stable emulsion. This study showed that suitable HPH combined with ISP treatments promoted the emulsifying stability of proteins.