Rheological, Thermal, Structural, and Chemical Changes during Oxidation of Gum Arabic by Ozone

Abstract

ABSTRACT Gum Arabic (GA) samples with 6% (w/v) concentration in water were ozonated for 5, 30, and 60 min, corresponding to 0.0030, 0.0125, and 0.0140 g consumed ozone/L, respectively. Ozonation steadily reduced the viscosity, flow, and consistency index of GA suspensions significantly (P < 0.05). Although no apparent changes were observed in the general chemical structure of GA samples, an increase in the absorbance of -OH bends was detected by FTIR analysis. DSC peak temperatures (292.0 ± 0.1 to 281.0 ± 0.9 °C) and pH values of samples (4.84 ± 0.13 to 2.90 ± 0.09) were decreased upon ozonation. Small but statistically significant differences (P < 0.05) were obtained for water solubility and water absorption index of samples after ozonation. Phenolic compounds and radical scavenging activities in GA were increased significantly (P < 0.05) by ozonation. Ozonation, which is an environmental-friendly unit operation, would offer valuable contributions to relevant industries with improved properties of GA.