Rheological, structural, and water-immobilizing properties of mung bean protein-based fermentation-induced gels: Effect of pH-shifting and oil imbedment

The objective of this study was to investigate the impact of pH-shifting and oil inclusion on the textural properties of plant protein-based fermentation-induced gels resembling dairy yogurt in consistency. Gels were formed by pH₁₂-treated or native mung bean protein (MBP) with or without emulsified coconut oil (3% w/v) and transglutaminase (0.1% w/w protein) during fermentation at 43 °C for 8 h. Quinoa flour hydrolysate was used to modulate the MBP gel network. Creep-recovery and viscoelasticity (Gʹ/Gʹʹ) tests showed that gels prepared with pH₁₂ treated MBP were less deformable and stiffer than native MBP gels. The pH₁₂ treated MBP gels also exhibited superior hardness and water-holding capacity over the native MBP gels. Consistently, the pH₁₂ gels displayed more compact and denser network structures, and oil emulsion droplets as well as transglutaminase further contributed to such packing effect. ¹H-LF-NMR confirmed less mobility of bulk water in pH₁₂ gels compared with native gels.