Effect of hydroxypropylation on morphological, rheological and thermal properties of wheat and oat starches

The main aims of this study were to modify wheat and oat starches in order to improve their functional properties and to investigate the resulting changes on the morphological، rheological and thermal properties of the modified starches. Therefore، wheat and oat starches were hydroxypropylated by addition of 30 mL propylene oxide at 40 oC for 24 hours. The extent of hydroxypropylation measured as molar substitution for wheat and oat starches were 0. 12% and 0. 09% respectively. Hydroxypropylation did not cause any considerable changes in the starch granular size and shape of oat starch، while، the granular structure of wheat starch was affected to some extent. The studies on the phase transitions associated with gelatinization of starch showed lower gelatinization parameters (To; Tp; Tc; and ΔH) for the hydroxypropylated starches. After hydroxypropylation of the samples، the peak viscosity، peak time and pasting temperature decreased while other viscosity parameters measured by RVA did not change considerably.