Emulsifying Properties of Polysaccharide Conjugates Prepared from Chin-Brick Tea

Chin-brick tea polysaccharide conjugates (TPC-C) were prepared to study their emulsion capabilities. Interfacial tension and the effects of some factors, such as storage time, metal ion concentrations (Na⁺, Ca²⁺), pH (2.0-8.0), and heat treatment (70-100 °C) on the emulsions stabilized by TPC-C were studied. The interfacial tension of TPC-C (10.88 mN/m) was lower than that of gum arabic (15.18 mN/m) at a concentration of 0.08%. As the TPC-C concentration increased from 0.1 to 3.0 wt %, the mean particle diameter (MPD) (d₃₂) of emulsions stabilized by TPC-C decreased from 1.88 to 0.16 μm. Furthermore, at a concentration of 0.5 wt % or higher, the MPD (d₃₂) of emulsions stabilized by TPC-C at 25 and 60 °C for 10 days was between 0.20 and 0.50 μm. In the tested pH conditions from 2.0 to 8.0, the MPD (d₃₂) of emulsions stabilized by 2.0 wt % TPC-C was less than 0.20 μm. At Na⁺ concentration conditions between 0.10 and 0.50 mol/L, the MPD (d₃₂) of emulsions was between 0.19 and 0.20 μm, and the zeta potential values varied from -34.10 to -32.60 mV. However, with an increasing Ca²⁺ concentration from 0.01 to 0.05 mol/L, the MPD (d₃₂) of emulsions was between 0.20 and 21.65 μm, and the zeta potential raised sharply from -34.10 to -28.46 mV. The emulsions stabilized by TPC-C have a decent storage stability after a high-temperature heat treatment. Overall, tea polysaccharide conjugates strongly stabilized the emulsions, which support their new application as natural emulsifiers.