Bing-Zheng Li

Preparation of starch nanospheres through hydrophobic modification followed by initial water dialysis.

Starch nanospheres smaller than 200 nm were produced from hydrophobically modified starch by using initial water dialysis method. The hydrophobic modification of starch was performed by using octenyl succinic anhydride (OSA). The resultant starch nanospheres were characterized by using Fourier transformation infrared (FTIR) spectroscopy, (1)H nuclear magnetic resonance ((1)H NMR) spectroscopy and fluorescence spectroscopy, scanning electron microscopy (SEM) and dynamic light scattering (DLS). Effects of degree of substitution (DS) in OSA-starch, initial water content and OSA-starch concentration on morphology and particle size of starch nanospheres were evaluated. The SEM micrographs showed that starch nanospheres with spherical shape and sharp edge can be produced at DS values ≧0.67. The particle size of starch nanospheres decreased significantly (P<0.05) with increase in DS of OSA-starch and increase in the initial water content, whereas the particle size increased significantly (P<0.05) with the increase in the concentration of OSA-starch. These OSA-starch nanospheres can be preferentially used to microencapsulate hydrophobic drugs.

Crystallization and melting properties of mixtures of milk fat stearin and omega-3 rich oils

Solid milk fat stearin (S25) can be a promising oxidation retarder due to its capacity to entrap liquid oils, especially for incorporating omega-3 (ω-3) rich oils into dairy products. Thermal properties of S25/ω-3 rich oil mixtures are necessary for such application. The effects of S25 on the crystallization and melting behaviours of ω-3 rich oils, namely fish oil (FO), linseed oil (LO) and krill oil (KO), were investigated by differential scanning calorimetry (DSC). Thermograms showed that with S25 concentration increasing, transitions of FO and LO shifted to lower and largely to higher temperatures, respectively, while crystallization temperature of KO slightly decreased. Negative, positive and low values of interaction enthalpy (ΔHint) suggested the adverse, beneficial and limited effect of S25 on the crystallization of S25/FO, S25/LO and S25/KO mixtures, respectively. LO could have the best oxidative stability upon the addition of S25 since their interactions facilitated earlier and stronger crystallization.

Effect of molecular weight of starch on the properties of cassava starch microspheres prepared in aqueous two-phase system

Starch microspheres (SMs) were fabricated in an aqueous two-phase system (ATPS). A series of starch samples with different molecular weight were prepared by acid hydrolysis, and the effect of molecular weight of starch on the fabrication of SMs were investigated. Scanning electron microscopy (SEM) showed that the morphologies of SMs varied with starch molecular weight, and spherical SMs with sharp contours were obtained while using starch samples with weight-average molecular weight (M¯w)≤1.057×105g/mol. X-ray diffraction (XRD) results revealed that crystalline structure of SMs were different from that of native cassava starch, and the relative crystallinity of SMs increased with the molecular weight of starch decreasing. Differential scanning calorimetry (DSC) results showed peak gelatinization temperature (Tp) and enthalpy of gelatinization (ΔH) of SMs increased with decreased M¯wof starch. Stability tests indicated that the SMs were stable under acid environment, but not stable under α-amylase hydrolysis.