Functional and physicochemical properties of fava bean protein concentrates obtained from isoelectric pH precipitation and membrane ultrafiltration

• Isoelectric pH-precipitated fava bean concentrate (FB_IEP) had a rigid conformation • FB_IEP could be used to formulate food emulsions and lipid containing foods • Fava bean protein concentrate from NaCl extraction (FB_UF) had a loose conformation. • FB_UF could be used to formulate food foams such as meringues and whipped cream Fava bean ( Vicia faba ) is gaining attention as a sustainable source of plant protein; however, variations in extraction methods can markedly alter protein structure and, consequently, functional behavior. This study compared two fava bean protein concentrates obtained through isoelectric precipitation (FB_IEP) and sodium chloride extraction coupled with membrane ultrafiltration (FB_UF) to elucidate how processing-induced conformational changes influence physicochemical and techno-functional properties. FB_IEP had significantly (p<0.05) higher protein yield (61.87%) and protein content (79.33%) than FB_UF (39.36% and 62.75%, respectively). However, FB_UF had significantly higher protein solubility (26 – 97%) at pH 5-9 when compared to FB_IEP. FB_IEP contained significantly higher branched chain amino acids (18.39%) and essential amino acids (47.47%) than the FB_UF (17.11% and 46.58%, respectively). FB_IEP also had significant (p<0.05) higher in vitro protein digestibility (83.67%) as well as water (2.25 g/L) and oil (2.83 g/L) holding capacity than the FB_UF (71.36%, 0.69 g/L, and 1.81 g/L, respectively). Far UV-Circular dichroism shows that these protein concentrates primarily exhibit an unordered structure, followed by β-sheets and β-turns, while α-helix conformations are present in the least amount. The mechanistic interpretation suggests that enhanced β-sheet/unordered structures improve hydration and unfolding, whereas α-helix dominance stabilizes interfacial and aggregation behavior. Denaturation temperature was higher for FB_IEP (66.03 °C) when compared to FB_UF (55.20 °C). FB_IEP also formed emulsions with smaller oil droplet sizes but had lower foaming capacity than the FB_UF. Overall, this study provides molecular-level insight into the structure–function relationships governing fava bean protein performance as a potential food ingredient. By linking secondary structure organization to functional outcomes, these findings establish a rational framework for optimizing pulse protein extraction processes and tailoring ingredient functionalities for specific food applications such as beverages, gels, and emulsions.