Gelatinization and retrogradation characteristics of wheat (Rosella) starch

The non-Newtonian behavior and elastic modulus of wheat (Rosella) starch solutions after preparation, and storage at 25 °C and 4 °C for 24 h were measured with a rheogoniometer. The flow curves of wheat starch showed plastic behavior above 4.0% solution. After storage at 4 °C in 4.0% solution, elastic modulus increased at low temperature and showed a constant value with increase in temperature. Elastic modulus increased upon addition of urea (4.0 M) at low temperature and remained constant up to 60 °C. Elastic modulus of Rosella also increased in 0.05 M NaOH solution after storage. Rheological characteristics of Rosella starch differed from those of rice starches. This might be caused by difference in structure of amylopectin and large amount of amylose content on starch.