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.

Preparation and properties of hydrogen peroxide oxidized starch for industrial use

Oxidized starch, an additive used in paper manufacturing and products for construction industry, is usually produced using harmful oxidant, such as hypochlorites or periodates. In this study, a simple and efficient eco-friendly laboratory and industrial procedures for starch oxidation were developed. The procedure involves application of small amounts of more environmentally friendly oxidant, hydrogen peroxide, a novel special metal complex catalyst such as copper(II) citrate and copper(II) ricinoleate and biobased plasticizers. Optimization procedure, with respect to the quantity of hydrogen peroxide and temperature in the presence of iron(II) sulphate catalyst, was performed by using the response surface methodology. Compa-rative analysis of the use of the other catalysts that is copper(II) sulphate, copper(II) citrate and copper(II) ricinoleate, indicated copper(II) citrate as the catalyst of choice. Improvement of starch is achieved using three plasticizers: ricinoleic acid (RA), diisopropyl tartarate, as well as epoxidized soybean, linseed and sunflower oils. The effects of hydrogen peroxide and catalyst concentrations, as well as the reaction temperature in the presence of naturally based plasticizers on the physicochemical, thermal and morphological properties of oxidized starch are presented. According to the results obtained in initial experiments, the optimal industrial process is based on the use of copper(II) citrate (0.1 %) as a catalyst and RA (3 %) as a plasticizer.

Oxidation of Oven-Dried Cassava Starch Using Hydrogen Peroxide and UV-C Irradiation to Improve Frying Expansion

Native cassava starch usually has low volume expansion. Some modifications were developed to change its physical and chemical characteristic, i.e. hydrogen peroxide addition and UV-C irradiation. The objectives of this study were to determine UV-C intensity, oxidation time, and concentration of hydrogen peroxide addition which resulted in the highest frying expansion of oven-dried cassava starch. Oxidation was conducted with acidification of cassava starch using 1% (w/w) lactic acid, the addition of hydrogen peroxide, and irradiation of UV-C in a tumbler. Combination of UV-C intensity, oxidation time, and hydrogen peroxide concentration were adjusted by Box-Behnken design. Optimization of cassava starch was determined by Response Surface Methodology (RSM), with frying expansion as a main response. Oxidized cassava starch was analyzed for physical and chemical characteristics. The result of this study showed that the oxidation of cassava starch increased the frying expansion, carbonyl and carboxyl content, amylose content, solubility, and decreased the swelling power. The optimum condition of oven-dried cassava starch oxidation was reached at 40 -watt UV-C intensity, oxidation time 2,281 minutes, and hydrogen peroxide concentration 1% (w/w), with the percentage of frying expansion 347,26%.