Comparative Effects of Pea, Soy, and Wheat Protein Preparations on the Properties of Structured Emulsions

Structured emulsions are a promising strategy for developing health-oriented fat alternatives in animal-, plant-, and hybrid-based food systems. Oil-in-water (O/W) emulsions are key matrices whose properties depend on the selection of stabilizing agents, including synergistically acting biopolymers. Polysaccharides with thickening or gelling properties, such as guar gum and agar, have considerable potential, especially when combined with plant proteins. Therefore, this study investigated the effects of soy, pea, and wheat protein preparations on guar gum- and agar-structured emulsions.
Structured O/W emulsions (30/70 m/m) were produced by hot homogenization (~80 °C) followed by refrigerated storage (~4 °C). Samples were analyzed after preparation and primary stabilization, and after heat treatment (~100 °C) and secondary stabilization. Color (CIEL*a*b* system, reflectance method), pH (potentiometry), texture (penetration test), mean oil droplet size and polydispersity index (optical microscopy), and oil-holding capacity (centrifugation) were determined. Data were statistically analyzed using ANOVA and Student’s t-test.
The use of plant protein preparations, regardless of type, resulted in a significant increase in the L* color parameter and oil-holding capacity, and decreases in pH, mean oil droplet size, and polydispersity index, along with increases in firmness and adhesiveness of the structured emulsions, compared with the control sample. These changes indicate improved system homogeneity and more effective immobilization of the dispersed phase. Emulsions containing soy or wheat protein preparations exhibited the highest firmness in the primary state and the greatest oil-holding capacity in the secondary state, indicating enhanced structural stability. The mechanisms of action differed: soy proteins acted mainly through emulsifying properties, whereas wheat proteins contributed primarily via mechanical entrapment of oil within the gel network.
It was found that the type of plant protein preparation significantly affects the properties of structured emulsions. Unlike pea proteins, wheat proteins have the potential to serve as a technological alternative to soy proteins for emulsion structuring.