Comparative Effects of Faba Bean Flour, Protein Concentrate and Protein Isolate on Gluten-Free Bread Quality: Insights from Techno-Functional Properties

Growing demand for gluten-free (GF) bread has intensified interest in protein-rich legume ingredients as alternatives to refined starch-based formulations. Faba bean (Vicia faba L.) is promising; however, flour (FBF), protein concentrate (FBPC), and protein isolate (FBPI) possess distinct techno-functional properties that may differentially influence bread quality. Techno-functional properties of FBF were characterised alongside prior data for FBPC and FBPI. An exploratory correlation analysis between techno-functionality and bread quality was performed. FBF was substituted with FBPC or FBPI, and breads were evaluated for specific volume, bake loss, crust and crumb colour (L*, a*, b*), texture, and crumb cell structure. Bread produced with FBF achieved a specific volume of 3.29 mL/g, crumb hardness of 10.04 ± 3.12 N, bake loss of 12.80 ± 0.77%, and a staling rate of 4.05 ± 0.81 N/day over the storage period. Substitution with FBPC and FBPI significantly reduced specific volume to 2.13 and 1.85 mL/g, respectively, and increased crumb hardness, while altering crust and crumb colour. The findings in this study provide a framework for understanding the effects of faba bean protein ingredients on GF bread performance and for guiding ingredient selection in future product development.