BACKGROUND: Gliadin nanoparticles are used as a delivery system for active substances because of their amphiphilicity and bioavailability. However, they are susceptible to destabilization by external agents. In this study, gliadin nanoparticles stabilized by soluble soybean polysaccharide (SSPS) were prepared by antisolvent precipitation. Formed stable complex nanoparticles were applied to protect and deliver curcumin (Cur). RESULTS: Gliadin/SSPS nanoparticles with the smallest particle size (196.66 nm, polydispersity index < 0.2) were fabricated when the mass ratio of gliadin to SSPS was 1:1 at pH 5.0. SSPS-stabilized gliadin nanoparticles had excellent stability at pH 3.0-8.0, 0.02-0.1 mol L −1 NaCl and at 90 °C heat. Gliadin/SSPS nanoparticles were used to encapsulate the Cur. The encapsulation efficiency of the Cur-loaded gliadin/SSPS nanoparticles was 84.59%. Fourier transform infrared spectroscopy and fluorescence spectrophotometry showed that the main forces were hydrogen bonds, electrostatic interactions and hydrophobic interactions between gliadin and SSPS. The X-ray diffraction patterns exhibited that the crystalline form of Cur converted to an amorphous substance. The retention rates of Cur-loaded gliadin/SSPS nanoparticles reached 79.03%, 73.43% and 87.92% after ultraviolet irradiation for 4 h, heating at 90 °C and storage at 25 °C for 15 days, respectively. Additionally, simulated digestion demonstrated that the bioavailability of gliadin/SSPS-Cur nanoparticles was four times higher than that of free Cur.CONCLUSION: This study showed that SSPS improved the stability of gliadin nanoparticles. Gliadin/SSPS nanoparticles have the function of loading and delivering Cur.

BACKGROUND Traditional soy protein isolate (SPI)‐based gel products, such as tofu, are generally produced by heating and by addition of metal salt ions to adjust the hydrophobicity and electrostatic force of soybean protein to facilitate the formation of a uniform network structure. However, the gelation rate of the soy protein gel network structure is difficult to control. Theoretically, epigallocatechin‐3‐gallate (EGCG) could be used to alter the surface hydrophobicity of thermally induced SPI to improve its gelation rate and form a more uniform network structure, thus improving SPI‐based gel properties (hardness, water holding capacity and rheological properties). RESULTS An SPI‐EGCG complex (SPIE) was prepared, and properties of the resulting gel, following induction of transglutaminase (TG), were evaluated. Results showed that EGCG is bound to thermally induced SPI primarily via hydrophobic and hydrogen bonding, thus altering the secondary structure composition and reducing surface hydrophobicity of proteins in thermally induced SPI. Furthermore, the optimum amount of EGCG required to improve the gel strength, water holding capacity and rheological properties was ≤0.04:1 (SPI 1 g L−1; EGCG:SPI, w/w). Thermal stability analysis further indicated that EGCG in SPIE was more stable than free EGCG after heating. CONCLUSION This study demonstrated that EGCG can improve the gel properties of TG‐crosslinked SPIE, while EGCG in SPIE exhibits enhanced thermal stability. Additionally, the results of this study provide a novel strategy for the development of SPI‐based gel foods with improved gel properties and that are enriched with bioactive compounds. © 2020 Society of Chemical Industry