Mechanistic investigation of a soybean protein isolate–soyasaponin–pectin composite system on soyasaponin bitterness in an acidic environment

Herein, a soybean protein isolate-soyasaponin (SPI-Ssa) composite system was constructed to mimic a complex, multifaceted soybean product system. This system was stabilized via the addition of high-methoxy pectin (HMP) and low-methoxy pectin (LMP), and the bitter taste of Ssa was modulated. HMP and LMP were compared using sensory evaluation and an electronic tongue assay, revealing that HMP was more effective in suppressing bitterness. Moreover, the interfacial properties and structural characteristics of the SPI-Ssa-HMP composite system were determined at different pH values, and the effect of composite coalescence on the adsorption of Ssa in acidic and neutral environments was investigated. The network structure formed between SPI and HMP was determined by differential scanning isothermal titration calorimetry and Fourier transform infrared spectroscopy. The formation of the network structure between SPI and HMP was more stable at pH 3.0, and the Tp value increased from 145.1 to 155.21 °C.