The effect of concentration on rheological properties of sago (Metroxylon sagu) starch

The concentration of starch is one of the main factors influencing the rheological characteristics of starch-based foods. The rheological behavior of sago starch at varied concentrations of 3, 5, 10, 20 and 30% (w/w) were investigated using small oscillatory temperature and frequency sweep measurements. All concentrations of sago starch expressed less solid-like behavior, with tan δ values of approximately 0.2. A flowable viscous paste of sago starch was generated at low concentrations (3 and 5% (w/w)). The gel network formation of sago starch initially occurred at a critical concentration of 10% (w/w). Further increases in the concentration to 20 and 30% (w/w), stronger gel network formation was occurred. In addition, the tan δ values for concentrations of 20 and 30% (w/ w) were approximately 0.2 with elastic and soft gel characteristics. A positive power law correlation between G' and sago starch concentration was found, with a coefficient of determination (R2 ) value of 0.99. The gelatinized sago starch was unstable as a frequency sweep was applied, indicating that it may be less stable during storage or processing.