High moisture extrusion of pulse proteins: Texture, structure, and in vitro digestion characteristics of extrudates

Pulse proteins are promising components for plant-based food development, yet their diverse subunit compositions, influenced by source origin, result in variable extrusion properties. This study utilized high moisture extrusion (60% moisture content) to prepare extrudates from four pulse proteins: soy, pea, chickpea and mung bean protein isolates (SPI, PPI, CPI, and MPI, respectively). The texture, structure, and in vitro digestion characteristics of extrudates were examined. The results showed that SPI and PPI were mainly composed of 7S and 11S globulins, while CPI and MPI were mainly composed of 7S globulins, and 11S globulins, respectively. SPI extrudates exhibited significantly lower hardness, chewiness, and transverse and longitudinal fracture stresses, while CPI extrudates exhibited a higher anisotropy index. SPI extrudates with a higher β-sheet content (39.08%) exhibited denser structures. The gastrointestinal digestibility (86.65%) of CPI extrudates was higher than other groups. Correlation analysis showed that 7S/11S ratio was positively correlated with the melt viscosity, while negatively correlated with the anisotropy index and in vitro digestibility. This study highlights the distinct extrusion properties of pulse proteins based on their unique subunit composition. The results provide insights for selecting appropriate protein sources and developing plant-based protein products with tailored textural attributes and desirable digestibility.