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

摘要

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) over barw) <= 1.057 x 10(5)g/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 (T-p) and enthalpy of gelatinization (Delta H) of SMs increased with decreased (M) over barw of starch. Stability tests indicated that the SMs were stable under acid environment, but not stable under alpha-amylase hydrolysis.