Effect of Transglutaminase on the Structure and Digestive Characteristics of High-Moisture Pea Protein Extrudates

The effect of adding different proportions of transglutaminase (TG) on the structure and digestive characteristics of high-moisture pea protein extrudates prepared with a twin-screw extruder was investigated. The macrostructure and microstructure of the extrudates were characterized by measuring texture and texturization degree as well as using a scanning electron microscope (SEM). The structural properties and nutritional value were evaluated by measuring rheological properties, protein solubility and digestive properties. These results showed that addition of appropriate amounts of TG (0.25%–­1.00%) promoted the cross-linking between pea protein molecules, forming a dense network structure, increasing the digestibility of extrudates and promoting the release of free amino acids. However, addition of excess TG (2%) inhibited the fiber formation and digestive properties of extrudates. The extrudate with 1.00% of TG had higher texturization degree and nutritional value. This study demonstrated that high-moisture extrusion combined with addition of TG can improve the structure and digestive characteristics of plant protein-based meat analogs.