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.

In this study, with the aim of pursuing environmental friendliness and maintaining the natural structure of pea protein, dry fractionation of pea protein was conducted by milling and subsequent air classification, yielding fine protein-rich fractions (protein fraction) and crude starch-rich fractions (starch fraction). The results showed that the protein content of the protein fraction separated by air classification at a rational speed of 10000 r/min was 54.16%. The storage modulus (G’) of gels from the protein fraction markedly increased compared with those of pea flour and the starch fraction. Furthermore, compared with commercial pea protein obtained by wet fractionation, pea protein obtained by dry fractionation lose no albumin (26 kDa) and had better preserved structure. Additionally, over the pH range of 3–7, the solubility was significantly higher than that of commercial pea protein, being 86% at pH 7. Therefore, this study provides theoretical and technical support for green and highly efficient production of high-quality pea protein with a low degree of denaturation.