Effects of Isolated Pea Protein on Extrusion-Induced Gelation and Gel-like Network Formation in Low-Moisture Meat Analog Systems

Low-moisture meat analogs (LMMAs) typically exhibit highly expanded structures with large air cells, which differ from the dense and fibrous architecture observed in high-moisture systems. This study investigated the role of isolated pea protein (IPP) in extrusion-induced protein gelation and gel-like network formation in LMMAs produced by low-moisture extrusion. By partially substituting isolated soy protein (ISP) with IPP, changes in expansion behavior, protein network structure, and gel-related physicochemical properties were systematically evaluated. Increasing IPP content markedly reduced expansion and air-cell size, leading to the formation of a dense and continuous gel-like protein network with enhanced fibrous alignment. At IPP substitution levels of 20-30%, the extrudates exhibited gel structures and fibrous characteristics comparable to those of high-moisture meat analogs. As IPP incorporation increased, water holding capacity, springiness, and cohesiveness declined, while mechanical resistance parameters, including chewiness, cutting strength, and integrity index, progressively increased, indicating gel network densification. Nitrogen solubility index analysis further revealed distinct protein denaturation and gelation behaviors between IPP- and ISP-based systems. These results demonstrate that controlled incorporation of IPP effectively modulates extrusion-induced gelation and gel network architecture in low-moisture meat analogs, providing mechanistic insights into gel-based structuring strategies for plant-based meat systems.