Modulating Molecular Interactions in Extruded Pea Protein Isolate

The impact of molecular interactions on the physical properties of extruded pea protein isolate (PPI) is investigated by adding interaction-modulating compounds to the matrix premix and studying the resulting variations in mechanical and physicochemical properties. Blends of PPI (water content 50% w/w) containing either sodium phosphate, urea, sodium dodecylsulphate and β-mercaptoethanol, as well as with all four compounds and only with deionized water (control) were extruded into thin strands (diameter ∼2.4 mm) using a lab-scale twin-screw extruder. The hardness from texture profile analysis (TPA) was the lowest for matrices extruded with β-mercaptoethanol and with all four chemicals, and highest for the control sample. The water holding capacity (WHC) of the matrices is lowest for the β-mercaptoethanol-containing matrix. These results are corroborated by the absorbance of the supernatant at λ = 280 and 600 nm. Our results confirm the importance of disulfide bonds in texturized PPI and show that hydrophobic and electrostatic interactions play auxiliary roles in modulating the properties of extruded PPI matrices. Our approach opens novel ways to modulate the physical properties of texturized plant protein matrices and thereby control their texture.