Acetylated Starch-Based Nanoparticles: Synthesis, Characterization, and Studies of Interaction With Antioxidants

Acetylated starch-based (cassava and oxidized starch) nanoparticles are prepared by nanoprecipitation method using water as non-solvent. Analyses of scanning electron microscopy (SEM) shows that nanoparticles (NPs) are obtained in spherical shape with average sizes between 500 and 900nm. The crystallinity of the samples is determined by means of Fourier Transform Infrared Spectroscopy (FTIR) and wide-angle X-ray diffraction (WAXD), which demonstrated that the produced NPs has lower crystallinity than their respective acetates. The incorporation of antioxidants (gallic acid [GA] and butylated hydroxytoluene [BHT)]) into the NPs is also evaluated, where a 90% incorporation was obtained for BHT while the incorporation for GA is only 10%. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) are performed in order to investigate thermal stability and interaction of antioxidants (AOs) with NPs. The glass transition temperature (Tg) of the NPs incorporated with BHT and GA are higher than that of pure NPs, indicating that the presence of AOs restricted the mobility of starch acetate chains. Kinetic degradation parameters are obtained by Horowitz and Metzger method. The results show that the incorporation of BHT increases the activation energy value for NPs. The interaction between BHT and starch acetate protects the AO from degradation process, thus increasing the thermal stability of NPs.