Alcoholic-alkaline treatment of sago starch and its effect on physicochemical properties

Sago starch (Metroxylon sagu) was subjected to an alcoholic-alkaline treatment using varied amounts of sodium hydroxide (NaOH) and a constant amount of ethanol at 35 °C. The cold water-solubility (CWS) of all the sago starches increased with an increase in the concentration of NaOH. For samples with high CWS, the Maltese-cross effect was absent when viewed under a light microscope. These granules were also larger than the native starches and had an indented appearance. The X-ray diffraction pattern changed from a C to a V for starches with high CWS. The amylose content of the treated sago starches increased significantly, whereas the intrinsic viscosity and peak viscosity values for treated starches were lower than the native starches. The gelatinization enthalpy decreased and was not detectable for sago starch with high CWS. It was evident that the alcoholic-alkaline treatment was effective for the production of granular cold water-soluble sago starches.

Research highlights▶ Granular cold water-soluble sago starch prepared using alcoholic-alkaline method. ▶ Cold water-solubility increased with increase in NaOH concentration. ▶ X-ray pattern changed from C to V indicating change in crystallinity. ▶ Gelatinization enthalpy decreased and not detectable for sago starch with high CWS.