The improved thermal stability of anthocyanins at pH 5.0 by gum arabic

Gum arabic (GA) was studied to improve the thermal stability of anthocyanins. Solutions with 0.51 mg/mL anthocyanins at pH 5.0 were heated at 80 and 126 °C up to 80 min with and without 10 mg/mL GA. The half-life of thermal degradation of anthocyanins at 80 and 126 °C was increased by 2.0 and 1.8 times, respectively, after adding GA. The residual concentration of anthocyanins with GA was 1.02 and 1.35 times higher than that without GA after 30-min heating at 80 and 126 °C, respectively. The DPPH and ABTS free-radical scavenging capacities and ferric reducing power after heating anthocyanin solutions with GA at 126 °C for 30 min were significantly higher than those without GA. Fluorescence spectroscopy data suggested the formation of complexes between anthocyanins and GA. Zeta-potential data suggested the formation of complexes by hydrophobic attraction. Stable particle size and zeta-potential of GA with and without anthocyanins were observed after heating. This study indicated that the assembled GA nanostructures significantly reduced the thermal degradation of anthocyanins at pH 5.0.