Effect of different surface properties of nanosilica on retrogradation behavior and structures of thermoplastic cassava starch

Thermoplastic cassava starch (TPS) /nanosilica (nano-SiO2) composites were prepared by adding different surface properties of nanosilica. The effect of different surface properties of nano-SiO2 on the retrogradation kinetics, morphology, spherulites size, molecular interactions, short-range molecular structure and crystal type of TPS was investigated by differential scanning calorimetry (DSC), polarized light microscopy (PLM), X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and C-13 NMR. The results indicated that the retrogradation degree and rate of TPS containing hydrophobic nano-SiO2 were higher than that of hydrophilic nano-SiO2, and the spherulites were clearer. Hydrophobic nano-SiO2 could uniformly disperse in starch matrix. V-type crystal formed after adding hydrophilic nano-SiO2, and A+V types after adding hydrophobic nano-SiO2. The crystallinity of TPS adding hydrophobic nano-SiO2 was higher than that of hydrophilic nano-SiO2, but the crystal size and interplanar spacing were smaller. Hydrophobic nano-SiO2 could promote the formations of double helix structure and the ordered molecular structure.

Automated summary

The study focused on the impact of different surface properties of nanosilica on thermoplastic cassava starch, revealing that hydrophobic nanosilica can enhance the crystallinity of cassava starch, promote the formation of double helix structure, and result in clearer spherulites.