Effects of heat moisture treatment on the physicochemical properties of starch nanoparticles.

In this study, the effect of heat moisture treatment (HMT) on the properties of waxy maize starch nanoparticles (SNPs) was investigated. The SNPs were adjusted to 20% and 30% moisture levels and heated at 90 °C and 110 °C for 4 h. Transmission electron microscopy, X-ray diffractometry, differential scanning calorimetry, and Fourier transform infrared spectroscopy were used to characterize the morphology and crystal structure of the SNPs after HMT. The research found that the morphology of SNPs did not change significantly, keeping nanoscale size. When the SNPs were subjected to HMT at 110 °C and 30% moisture content, the crystalline structures changed from B-type to A-type, and the crystallinity of the SNPs increased significantly. HMT significantly increased the onset temperature, peak temperature, final temperature, and enthalpy value of the SNPs. As the HMT temperature and SNP moisture content increased, the hydrogen bonds between the starch molecular chains in the SNPs became stronger.