Abstract: In this study, a combined method of physical and chemical modification was used to improve the functional characteristics of porcine liver protein (PLP). PLP was modified by mild heating assisted alkaline pH shift treatment. The hydration properties, surface properties, particle size distribution, denaturation degree and molecular structure of modified PLP were measured. The results showed that heat treatment combined with a large shift in pH toward the alkaline side significantly increased the solubility and emulsifying activity of PLP, reduced the particle size while resulting in uniform size distribution, increased the absolute value of zeta potential, and decreased the free sulfhydryl content, changed the primary, secondary and tertiary structures, and increased the surface hydrophobicity. The combined treatment was superior to either treatment alone. In terms of improvements in the hydration and surface properties of PLP, heating at 50 ℃ combined with pH shift toward pH 11 was the best modification condition for PLP.

Key words: mild heat treatment; pH shift; porcine liver protein; protein structure; functional characteristics