Abstract:

Differences in the physio-chemical properties of slowly digestible starch (SDS) prepared from maize and waxy maize starch (WMS) were investigated using scanning electron microscope (SEM), X-ray diffraction, and Brabender viscometer. The data from SEM revealed that SDS granules were irregular and angular in shape and packing of starch granules was loose. The Xray diffraction patter showed significant alteration of SDS in comparison with native starch as well as the reduction in the crystallinity to 29.65%. The starch gelatinization of SDS was found to occur at 72.5 ℃ and the maximum viscosity reached 41 BU at 77.5 ℃. The starting gelatinization time of SDS was a little earlier than that of the native starch while the time required to reach the maximum viscosity was longer. Obvious polarized light cross was observed in native starch granules instead of SDS. The specific volume of SDS was reduced from 1.8 cm3/g of the origin starch to 1.25 cm3/g as well as the decrease of solubility from 14.78% to 1.36%. The transmittance and whiteness of SDS were found to be reduced from 12.2% of native starch to 1.63% and from 97.2 to 81.6, respectively.

Key words: slowly digestible starch, physico-chemical property