Network formation in pea protein-based meat substitutes: effects of pH, oil, and pectin-based microgel particles

As consumer awareness of the environmental and health impacts of excessive meat consumption grows, so does interest in plant-based meat substitutes. High-moisture extrusion of protein isolates is an emerging method for producing anisotropic, meat-like structures. However, sensory differences in texture remain a challenge. This study investigates the formation of protein networks in pea protein isolate (PPI) meat substitutes when the pH is adjusted, in a range of pH 3.3 to 11.1, using either hydrochloric acid or sodium hydroxide, or when canola oil and pectin-based microgel particles (MGP) are added. Network formation was investigated using a closed cavity rheometer, and meat substitutes were produced using a laboratory-scale extruder. Both acidic and alkaline pH adjustments affected the protein network formation. Under acidic conditions, the network is mainly strengthened. Under alkaline conditions, disulfide bond formation was accelerated. The anisotropic, meat-like structure disappeared under acidic conditions, but a slight increase in pH resulted in more pronounced fibrous structures. The addition of oil (ϕ_oil,max = 3.3 wt%) decelerated the formation of disulfide bonds but did not affect the formation of fibrous structures in the extrudates. MGP did not seem to influence network formation; the structure of the meat substitute remained unchanged. These results demonstrate that the texture of plant-based meat substitutes produced by high-moisture extrusion can be effectively altered by pH modulation and that network formation investigation can indicate structural changes.