The shortening of shelf-life of food emulsions is frequently due to poor creaming and lipid oxidation stability. The lipid oxidation of O/W emulsions can be inhibited by rice dreg protein hydrolysate (RDPH); however, emulsions were stabilized by Tween-20. Polysaccharides can control the rheology and network structure of the aqueous continuous phase by increasing viscosity and yield stress, hence retarding phase separation and gravity-induced creaming, especially for xanthan gum. The objective of this research was to evaluate whether emulsions formed with 2 wt% RDPH and stabilized by xanthan gum (0–0.5 wt%) could produce 20 % (v/v) soybean oil-in-water emulsions that had good physical and oxidative stability. The degree of flocculation of droplets as a function of xanthan gum concentration was assessed by the microstructure, rheology, and the creaming index of emulsions. Addition of xanthan gum prior to homogenization had no significant effect on the mean droplet diameter in all emulsions studied. Increase in xanthan gum concentration led to the increase in creaming stability of emulsions, due to an increase in viscosity of the continuous phase and/or the formation of a droplet network with a yield stress, as well as the enhanced steric and electrostatic repulsion between the droplets. Lipid oxidation of the emulsions was significantly inhibited at xanthan gum concentrations of 0.12 wt% or above with RDPH, which could due to the fact that xanthan gum increases the viscosity of the aqueous phase and hindered the diffusion of oxidants to the oil droplet surface area, synergistic effect between RDPH and xanthan gum to suppress oil peroxidation, and metal ion chelation capability of xanthan gum. Thus, stable protein hydrolyzates-type emulsions could be obtained with increasing concentration of xanthan gum.

•Acid deamidation is a mild treatment process to potentially improve the functional and rheological properties of glutelin.•Significant increasing in solubility and emulsifying properties of glutelin was found after deamidation.•Characteristics of glutelin deamidated with malic acid and citric acid were investigated.The characteristics of glutelin samples from Akebia trifoliata var. australis seeds (AG) that had been deamidated by malic acid (MDAG) and by citric acid (CDAG) were investigated. Sodium dodecyl sulfate–polyacrylamide gel electrophoresis showed high-molecular-weight subunits that were degraded into smaller fragments, and FTIR indicated a decrease in the number of β-sheet groups and an increase in the amount of β-turns in the deamidated samples. These results could be caused by the cleaving of partial disulfide bonds to form new sulfhydryl groups during deamidation. Citric acid was found to be more effective at deamidation and hydrolysis, resulting in a higher solubility and emulsifying activity for CDAG, and MDAG also exhibited some improvement in terms of surface hydrophobicity and emulsion ability. Rheology showed that the gelation point for deamidated samples was increased, and the gel network was strengthened. The amounts of essential amino acids that were well-preserved and the improved solubility, emulsification, and rheology properties of AG after acid-heating deamidation show that this technique can be useful for treating other plant-based food ingredients in the future.