Characteristics of Pickering emulsions stabilized by tea water-insoluble protein nanoparticles at different pH values

This study aimed to explore the characteristics of Pickering emulsions stabilized by tea water-insoluble protein nanoparticles (TWIPNs) at different pH values. The characteristics of TWIPNs at different pH values were analysed first. The average hydrodynamic diameter of TWIPNs in the suspension was smaller than 400 nm at pH 7-11. TWIPNs at pH 3 could not be used to stabilize Pickering emulsions. The flocculation index (FI) of fresh TWIPN-stabilized Pickering emulsions (TWIPNPEs) at pH 5 was higher than those of TWIPNPEs at pH 7-11 (FI < 5%), indicating that bridging flocculation led to the aggregation of small emulsion droplets. The zeta potential of TWIPNPEs at pH 7-11 did not change after 7 d. In addition, the TWIPNPEs showed gel-like properties under neutral and alkaline conditions. These results will be helpful for broadening the application of TWIPNPEs at different pH values.

Automated summary

The study found that the characteristics of TWIPNs vary at different pH values, with the inability to stabilize Pickering emulsions at pH 3. Results also showed that TWIPNPEs at pH 5 had higher flocculation index, indicating aggregation of small emulsion droplets due to bridging flocculation. Moreover, TWIPNPEs at pH 7-11 maintained zeta potential and exhibited gel-like properties under neutral and alkaline conditions.