Structural and digestibility characterization of soybean protein, textured soybean-based protein and chicken breast: a comparative study

Plant-based meat analogs, primarily composed of textured vegetable proteins (TVPs), are potential alternatives to traditional meat. However, there is a lack of research on the digestibility properties of TVPs. This study involved processing soybean protein concentrate (SPC) into soybean-based high-moisture extruded TVPs (SH) and soybean-based low-moisture extruded TVPs (SL) through high-moisture (HM) extrusion and low-moisture (LM) extrusion, respectively. A comparison was then made between the structural and digestibility characteristics of SPC, SH, SL, and chicken breast. HM and LM extrusion transformed the soybean protein molecular structure from spherical into fibrous like in chicken breast, decreased its α-helix/β-sheet value from 0.68 ± 0.01 to 0.63 ± 0.01 and 0.60 ± 0.00, respectively, increased its intrinsic fluorescence maximum absorption wavelength from 341.4 nm to 352.2 nm and 350.2 nm, respectively, reduced its surface hydrophobicity index from 8665 ± 519 to 6723 ± 285 and 5167 ± 321, respectively, and greatly decreased the peptide molecular weight of digestive products. The findings suggested that, compared with natural SPC, soybean-based meat analogs were more similar to chicken breast in terms of appearance, protein molecular structure and digestibility characteristics, but there were still significant differences between the two. These results offered a scientific foundation for further exploration of plant-based meat alternatives.