Modulating 11S/7S ratios in lactic acid bacteria-fermented soy protein gels: effects on physicochemical properties...

Lactic acid bacteria (LAB) fermentation induces acidic coagulation of soy proteins, primarily composed of β-conglycinin (7S) and glycinin (11S), which exhibit distinct gelation behaviors and allergenic potentials. However, the influence of varying 11S/7S ratios on gel formation kinetics and allergenicity modulation remains unclear. In the present study, we systematically investigated soy protein systems with controlled 11S/7S ratios (FSPI-7S, FSPI-0.5, FSPI-1.0, FSPI-2.0, FSPI-3.0, FSPI-4.0 and FSPI-11S for brevity) under fermentation pH gradients (7.0, 6.5, 6.0, 5.5 and 5.0) to elucidate their synergistic effects on protein aggregation and immunoreactivity.

Higher 11S globulin content accelerated protein gelation, with FSPI-11S (100% 11S) gelling at 6 h, FSPI-2.0, FSPI-3.0 and FSPI-4.0 (11S/7S ratio > 1.0) at 8 h, and FSPI-7S, FSPI-0.5 and FSPI-1.0 (11S/7S ≤ 1.0) at 24 h of fermentation. Turbidity and particle size analyses at pH 5.0 confirmed that 11S/7S ratios > 1.0 promoted protein aggregation. Microscopic examination showed that these ratios (≥ 1.0) resulted in denser gel matrices with reduced void formation. Electrophoretic mobility studies revealed that, at pH 6.0, 11S/7S ratios > 3.0 enhanced protein migration and facilitated the incorporation of β-conglycinin subunits into the gel matrix, with preferential migration of basic subunits into the gel network during acid-induced gelation. At pH 6.0, antigenicity assessment revealed superior desensitization occurred when the 11S/7S ratios > 1.0, with FSPI-4.0 exhibiting the lowest antigenicity (6.50%) and FSPI-3.0 exhibiting the lowest immunoglobulin E binding capacity (12.16%).

The 11S/7S ratio critically governs soy protein gelation properties, where 11S/7S ratios > 1.0 accelerate gel formation, enhance aggregation, and improve matrix density. Superior antigenicity reduction occurs at pH 6.0 with 11S/7S ratios > 1.0. © 2025 Society of Chemical Industry.