Tailoring the structural and rheological properties of fava bean protein isolates extracted using deep eutectic...

This study evaluated how deep eutectic solvent (DES)-based protein extraction influences the heat-induced gelation of fava bean proteins, in comparison with alkaline and salt extraction methods, using commercial soy protein isolate as a reference. The final storage modulus (G') differed significantly among the gels (p < 0.05). DES-extracted fava bean isolate gels (DES-FBG) showed a higher G' (16.39 ± 0.30 kPa), followed by salt-extracted fava bean protein isolate gels (SS-FBG) (11.85 ± 2.65 kPa), commercial soy protein gels (CSG) (9.41 ± 0.13 kPa), and alkaline-extracted fava bean protein isolate gels (ALK-FBG) (3.91 ± 0.36 kPa). All gels were primarily stabilized by hydrophobic interactions. CSG exhibited the highest hydrophobic interaction (8.90 ± 0.08 mg/mL) and decreased the order of DES-FBG (5.44 ± 0.39 mg/mL) > ALK-FBG (4.67 ± 0.30 mg/mL) > SS-FBG (2.62 ± 0.32 mg/mL). Disulfide bond content was not significantly different between DES-FBG (2.67 ± 0.60 mg/mL) and SS-FBG (1.69 ± 0.57 mg/mL) (p > 0.05), but both were higher than ALK-FBG (1.35 ± 0.08 mg/mL) and the CSG (0.32 ± 0.02 mg/mL). This indicates that the relatively higher hydrophobic and disulfide interactions in DES-FBG contribute to the formation of a strong gel network, as supported by its homogeneous, well-connected, fine-stranded microstructure. In contrast, ALK-FBG and SS-FBG formed weak gel networks characterized by irregular, loosely stacked protein aggregates with larger pores. Overall, the findings demonstrate that DES-based protein extraction is a promising and sustainable alternative for developing plant-based gel products.