Physical and oxidative stability of oil-in-water (O/W) emulsions in the presence of protein (peptide): characteristics analysis and bioinformatics prediction

Abstract The physical and oxidative stability of soybean protein hydrolysate-stabilized oil-in-water (O/W) emulsions created via limited hydrolysis using Alcalase (15, 30, 45, 60, 90, 120, and 180 min) was investigated. The extracted emulsion protein exhibited significantly lower surface hydrophobicity, higher antioxidant properties, and a greater proportion of β-sheet and α-helix structures than soybean protein isolate. The physical stability of the emulsions was characterized by particle size, zeta-potential, rheological property, and multiple light scattering. The emulsion obtained by enzymatic hydrolysis for 90 min (90 min-E) had the highest physical stability, showing the smallest droplet size, uniform droplet distribution, lowest zeta-potential, lowest Turbiscan stability index, and larger G′ and G″ values. It also exhibited the highest oxidative stability, as evidenced by the thiobarbituric acid-reactive substances test. Due to the good physical and oxidative stability of 90 min-E, LC-MS/MS analysis and bioinformatic tools (Chou−Fasman secondary structure prediction and the BIOPEP database) were conducted on the protein extracted from 90 min-E. These data provided insight into the mechanism of emulsion-stabilizing action by the emulsion protein (peptide) and identified potential bioactive peptides. This new strategy of producing stable O/W emulsions will likely expand its application to nutrient components or effective wall materials.