Comparative study of high‐intensity ultrasound and high‐pressure homogenization on physicochemical properties of peanut protein‐stabilized emulsions and emulsion gels

Abstract

AbstractThe physicochemical properties of peanut protein‐stabilized emulsions and emulsion gels prepared by high‐intensity ultrasound (HIU) and high‐pressure homogenization (HPH) were compared. The effects of different ultrasound emulsification conditions (ultrasonic time and power, protein concentration, and oil phase percentage) on the initial particle size and stability of peanut protein‐stabilized emulsions were investigated. It was observed that the optimal HIU emulsification conditions consisted of a concentration of 4% (w/v) proteins, a volume percentage of 30% (v/v) oil, and an ultrasonic treatment at 300 W for 20 min. Compared with the two emulsions prepared by HPH at 300 and 500 bar, respectively, the HIU‐prepared fresh emulsion showed a larger particle size, similar zeta potential but higher interfacial protein concentration and apparent viscosity. Additionally, the HIU‐prepared emulsion had lower flocculation and coalescence indices and was more resistant to gravitation separation during storage. The cold‐set gel strength of the HIU‐prepared emulsion was stronger than that of the HPH‐prepared emulsion (300 bar), but weaker than that of the emulsion (500 bar). The non‐adsorbed proteins from the HIU‐prepared emulsion had unique structural characteristics, such as higher molecular weight, more unordered secondary structures, and stronger surface hydrophobicity, which likely explained why the HIU‐prepared emulsion possessed better physical stability and gelling ability.Practical ApplicationsHigh‐pressure homogenization (HPH) is currently the most frequently used method in the food industry to produce emulsions. However, a high‐pressure homogenizer is expensive and not easy to operate. In contrast, high‐intensity ultrasound (HIU) emulsification is considered a cost‐effective technique. In this study, a peanut protein‐stabilized emulsion was successfully produced by HIU emulsification method. Its physical stability was significantly better than that of the emulsions made by HPH. This work provides new knowledge for the application of peanut protein as a natural emulsifier combined with ultrasonic technology in the food industry.