Oxidation of cassava starch at different dissolved ozone concentration: effect on functional and structural properties

An environmentally friendly method for starch oxidation is recommended in order to replace harmful oxidizing chemical reagents. Ozone is an environmentally friendly oxidizing reagent that leaves no residue in the final product. Studies of starch modification using dissolved ozone are still lacking. This work aimed to increase the use value and improve native starch characteristics by evaluating carbonyl and carboxyl contents, pasting and functional properties, spectral Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) profiles, particle sizes, and scanning electron micrographs (SEM) of ozone-oxidized cassava starch. The results showed that dissolved ozone and starch slurry concentrations significantly affected oxidation degree, functional properties and caused a decrease in particle size and pasta viscosity of cassava starch. FTIR spectra significantly showed an increase in the intensity of the presence of the carbonyl group as a marker of starch oxidation. Further XRD diffraction also significantly showed changes in the relative crystallinity besides that there is a change in the surface morphology of the starch granules. Oxidized starch with a combination of 1.4 ppm dissolved ozone concentration and a starch slurry ratio of 1:10 produced higher swelling power (44.31%), solubility (0.88%), lower paste viscosity (6082.5 cP), and reconditioning relative crystallinity (10.44%). Overall, dissolved ozone successfully had powerful effects in oxidizing starch and can be applied for starch modification as an inexpensive and safe oxidizing agent.