Preparation and characterization of high degree substituted sago (Metroxylon sagu) starch with propylene oxide

The effects of etherification on properties of sago starch were investigated. Hydroxypropylated sago starch (HPSS) was prepared in basic medium in ratios ranging from 0 to 70% v/w propylene oxide to sago starch. The physicochemical, thermal, and rheological properties of HPSS were determined. The highest molar substitution (MS) obtained for HPSS was 0.66. DSC studies showed that the gelatinization temperature and enthalpy of HPSS decreased with increasing MS. Starch with a high MS (MS > 0.15) exhibited cold water solubility up to 100%, with very minimal retrogradation and no syneresis during freeze–thaw cycles. Highly substituted starch exhibited different properties than starch with lower MS values (MS ≤ 0.1). Thus, hydroxypropylation could be used to modify properties of starch for specific applications such as coating of nuts as well as foods.