Ozonation of corn starch in the presence of guar gum: Rheological, thermal and antioxidant properties

Effect of different ozonation times (i.e., 5, 10, 15, 30 and 60 min) on rheological, thermal and chemical properties of guar gum (GG), corn starch (S) and GGS dispersion (GGS) were investigated for the first time in the literature. Ozonation has reduced viscosity of samples to provide possible ease of use in the industry. The frequency crossover points of GG decreased after ozonation while an increase was observed for GGS, showing that ozonation resulted in a more structurally resistant state for GGS. The pH values of the samples decreased as the ozonation time increased, which was associated with increased formation of carbonyl and carboxyl groups due to possible hydroxyl oxidation by ozonation. Ozonation has made it more advantageous for GG, S and GGS samples in terms of use in the food industry by increasing the water solubility index and decreasing the water adsorption index. The increase in the peak temperature of GGS upon ozonation was attributed to increased temperature endurance of the sample by ozonation. It was found that ozonation increased the reducing sugar contents in GG, S and GGS samples as well as the concentration of phenolic compounds and radical scavenging activities. The results of this study may suggest that ozonation being an environmentally friendly method could be used to oxidize GGS dispersion to provide an alternative to conventional oxidation processes.