Investigation of the photo-oxidation of cassava starch granules

Abstract

In this study, the combined and simultaneous actions of H2O2 and UV radiation on cassava starch granules were applied and the thermal, rheological, structural and colour properties were investigated. Samples of native cassava starch were oxidised with standard H2O2 solutions (0.1, 0.2 and 0.5 mol L−1) and exposed for 1 h under UV light (UVC radiation with λ = 256 nm), with constant stirring. The solutions were subsequently filtered, washed, dried and analysed. The thermogravimetric curves showed similar behaviour, with three main mass losses and an increase in the thermal stability of each sample. The oxidative modification performed caused a strong decrease in the setback and final viscosity parameters (RVA), a gradual decrease in the gelatinisation enthalpy (DSC) and relative crystallinity (XRD) and significant differences in the average roughness of the granules (NC-AFM). The X-ray diffraction powder patterns displayed the “A” type for all the starch granules. The colour parameters showed a decrease in the −a* value (trend to green) for all the treated samples.