By 2050, global demand for animal products is projected to increase by 70 % due to population growth, rising incomes, and urbanization (Huang et al., 2022; Qi et al., 2025). However, meat production is associated with severe environmental impacts, including greenhouse gas emissions, high water consumption, depletion of natural resources, and biodiversity loss, among others (Beniwal et al., 2021; Fu et al., 2023; Qi et al., 2025; Schmid et al., 2022). To mitigate these issues, the replacement of meat with alternative protein products is being promoted. In this regard, plant-based meat analogues (MA) have emerged as promising alternatives due to their fibrous texture and organoleptic resemblance to meat and meat-derived products (Chen et al., 2022; Huang et al., 2022; Mateen & Signh, 2023). MA are protein-rich products that can be produced by multiple structuring techniques, including cell culturing, 3D printing, freeze structuring, extrusion, electrospinning, among others (Beniwal et al., 2021; Choi et al., 2024).

High-moisture extrusion (HME) is currently the most widely applied technology for the production of MA given its water and energy efficiency, scalability, high production capacity, and versatility (Chen et al., 2022; Choi et al., 2024; Qi et al., 2025). In this thermomechanical process, protein-rich ingredients are fed into an extruder where they undergo hydration, mixing, heating, and shearing, leading to proteins denaturation and alignment, forming a molten mass that is subsequently cooled in a cooling die to stabilize the fibrous structure (Beniwal et al., 2021; Chen et al., 2011; Schmid et al., 2022; Zhang et al., 2019). One of the main advantages of HME is its ability to produce plant-based products with a dense, layered texture, and high water retention, contributing to a juicier, more meat-like mouthfeel (Choi et al., 2024). In that sense, soy protein isolate (SPI) is commonly used as a base material due to its high viscosity, gelling properties, water holding capacity, and the ability to form disulfide bonds and non-covalent interactions that stabilize the fibrous structures (Chakraborty et al., 2024; Chen et al., 2011; Choi et al., 2024; Zhang et al., 2018; Zhang et al., 2019; Zhang et al., 2023). Despite advancements in the generation of MA, replicating the complex fibrous microstructure and anisotropic appearance of meat remains challenging, as structuring depends on precise control of formulations and processing conditions. To address this, proteins are often combined with other biopolymers, particularly carbohydrates, to improve textural and structural properties (Fu et al., 2023; Huang et al., 2022; Mateen & Signh, 2023; Nanta et al., 2021; Rolandelli, Ozturk, Velasquez Giraldo, Hamaker and Campanella, 2024, Rolandelli, Ozturk, Velasquez Giraldo, Hamaker and Campanella, 2025; Zhang et al., 2020; Zhao et al., 2025). Carbohydrates enhance texture through water retention and thickening properties, while thermal incompatibility between proteins and polysaccharides can promote anisotropy (Bühler et al., 2022; Dahl et al., 2025; Huang et al., 2022).

Nonetheless, starch incorporation into SPI-based systems has been scarcely studied as an strategy to improve the techno-functional properties of MA. In this regard, Zhang et al. (2016) reported that starches with higher enthalpy transitions increased hardness but reduced fibrous degree of soy-based MA. In another study, wheat starch promoted fiber formation and improved mechanical properties by altering water distribution, enhancing disulfide bonds and increased amounts of ordered secondary structures of proteins (Zhao et al., 2025). Conversely, the replacement of soy with zein and rice starch produced softer and less elastic products given the high water holding capacity of starch, with reduced fibrillar structures (Rolandelli et al., 2025). Furthermore, starch composition plays a role: amylopectin supports fibrous structuring, while amylose favors layered, gel-like textures (Chen et al., 2022).

Based on these results, a deeper understanding of protein-starch interactions is needed to better predict macroscopic product properties and optimize processing strategies. Therefore, this study aimed to investigate the effects of potato starch (PS) addition at different levels on the physicochemical and textural properties of SPI-based MA, with particular focus on the relationship between starch-induced structural changes and protein secondary conformations.