Effect of NaCl concentration on stability of high internal phase emulsions of insoluble fiber from rice bran/soybean protein isolate

ObjectiveThis paper aims to broaden the application of insoluble dietary fiber from rice bran (RBIDF) in food.MethodsThe impact of NaCl concentration (ranging from 0 to 100 mmol/L) on the stability of high internal phase emulsions (HIPEs) co-stabilized by RBIDF and soybean protein isolate at pH 2, with RBIDF additions of 0.20 and 0.30 g/100 g, was studied by analyzing ζ-potential, particle size distribution, rheological properties, visual appearance, and freeze-thaw stability.ResultsAll emulsions under different NaCl concentrations exhibited robust gel-like network structures. When RBIDF was added at 0.20 g/100 g, and NaCl concentration exceeded 25 mmol/L, the viscoelastic behavior gradually intensified with increasing NaCl concentration. Conversely, at an RBIDF addition of 0.30 g/100 g, the increase in viscoelasticity was less pronounced with rising NaCl concentration. The addition of NaCl significantly improved the freeze-thaw stability of the HIPEs with both RBIDF additions. Notably, under relatively high salt conditions of 75 and 100 mmol/L, the HIPEs maintained excellent self-supporting emulsion states even after two freeze-thaw cycles.ConclusionThe addition of NaCl can significantly enhance the freeze-thaw stability of HIPEs formulated from a blend of RBIDF and soybean protein isolate.