The effect of legume protein source, solubility, pH, and salt addition on the texture of meat analogues

Variability in the composition and properties of plant proteins presents challenges in developing plant-based meat analogues that have comparable texture to animal-based meats. This study investigated four plant protein isolates to understand the effects of protein source, pH, and salt addition on pasting properties, protein solubility, protein secondary structure, extruder response, and the resulting textural properties. The protein solubilities and paste viscosities of all investigated protein sources were lowest at pH 4. Calcium ion addition also reduced protein solubility in all protein isolates at pH 6 and in water. Modulation of pH and salt concentration resulted in the tuning of extrudate texture for only one protein source, Yellow Pea UF (ultrafiltration) protein isolate. Higher die pressure and specific mechanical energy was found to correlate with higher extrudate cutting forces. Scanning electron microscopy of the extrudates showed a smooth structure formed by proteins with lower solubility and in contrast, a more porous structure with the proteins with higher solubility. Notably, yellow pea and faba bean protein isolate with high solubility showed an increase in disordered structures after extrusion. This study demonstrates that plant protein source, pH, and salt addition can be effectively used to modulate extruder response and meat analogue texture.