Time-Dependent Effects of Ultrasonic Modification of Soy Protein Concentrate on the Mixolab Rheology of Enriched...

Soy protein concentrate (SPC) often has limited food applications due to the loss of its functional properties under harsh industrial processing. This study explored the effects of exposure time to high-intensity ultrasound (HUS) on the structural properties of SPC to assess the potential of a single protein for multiple bakery applications. HUS treatment modified SPC free sulfhydryl group content (4.81 ± 0.03 to 1.47 ± 0.01 µmol/g_protein) and hydrophobicity (34.17 ± 0.02 to 30.56 ± 0.03 µgBPB/mg_protein) and promoted the formation of soluble and insoluble aggregates, especially with longer exposure times, as evidenced by SDS-PAGE. According to Raman analysis, SPC exposed to 0.5 min HUS exhibited an α-helical content of 33.52 ± 1.58% and β-sheet content of 56.80 ± 4.40%, while the tyrosine doublet (I₈₅₀/I₈₃₀) ratio was associated with dough stability and indicated intermolecular hydrogen bonding within the dough matrix. Water absorption capacity was improved upon addition of HUS-exposed SPC samples, to 58.4 ± 0.71%, compared with 52.6 ± 0.85% of SPC-enriched dough. These changes accelerated dough development time and enhanced amylase activity, resulting in a dough with desirable viscosity. HUS-exposed samples with higher α-helix content and solubility, decreased water syneresis, and hydrophobic SPC formed stabile complexes with hydrophobic regions of the amylose chain, both leading to reduced starch retrogradation (1.551 ± 0.13 to 0.855 ± 0.04). Overall, this study showed that by controlling the HUS treatment time, protein structure can be tailored for its use in diverse bakery applications, further enhancing the commercial value of protein concentrates.