Mechanistic understanding of the effects of nanoliposome-soybean protein isolate interactions on soybean protein isolate emulsifying properties

Abstract

The purpose of this study was to reveal the mechanism of the improvement of SPI emulsifying properties after complexation with NL. The binding between NL and SPI led to a static fluorescence quenching of SPI and the significant change of SPI FTIR spectra. It indicated that the advanced structure of SPI after interaction with NL was altered appreciably. Moreover, it was observed that the free sulfhydryl content, contact angle, particle size, zeta potential, and surface hydrophobicity of SPI after complexation increased, and the interfacial tension reduced. Hydrophobic forces and hydrogen bonds played a vital part in the interaction between NL and SPI. Furthermore, the emulsifying properties of SPI were significantly improved after complexation with NL. Emulsifying activity index (EAI) and emulsifying stability index (ESI) of SPI increased from 50.52 to 104.28 m²/g and from 17.30 to 25.10 min with the NL-to-SPI mass ratio increasing from 0:1–1:1, respectively. Meanwhile, the emulsifying properties of NL-SPI (the NL-to-SPI mass ratio at 1:1) were also influenced by environmental factors (pH, temperature, and ionic strength). The improvement of the emulsifying properties of SPI after interaction with NL derived from the alteration of advanced structure and surface characteristics of NL-SPI complexes.