Characterisation of 2-octen-1-ylsuccinylated waxy rice amylodextrins prepared by dry-heating

Waxy rice amylodextrins substituted with 2-octen-1-ylsuccinic acid (OSA) were prepared by heating a dried mixture of waxy rice starch and OSA (3% OSA based on starch solids) at 130–150 °C and pH 3–5 for 1–3 h. The effects of the heating conditions, such as pH, temperature and heating time on the degrees of substitution (DS) and dextrinisation, and the physical properties of the dextrins were evaluated. Substitution and dextrinisation were more affected by the reaction pH than by the physical conditions (temperature and time). Heating under a more acidic condition resulted in a higher DS and a lower molecular weight (Mw). Pasting viscosity profiles showed reduced pasting temperatures but increased peak viscosities, due to the presence of OSA, compared to unsubstituted dextrin counterparts. The X-ray diffraction patterns of the OSA dextrins were similar to that of the native starch, indicating that the dextrinisation occurred mainly in the amorphous regions of the starch granules. Fat-free whipped creams were prepared with the OSA dextrins and skim milk powder to examine the fat-replacing effects of the dextrins. The OSA dextrins effectively substituted the fat in dairy cream, providing good foaming ability and storage stability.