Engineering Properties of Different Commercial Grades of Sago (Sabudana)

Abstract

Sago is a traditional food product of India made exclusively from fresh wet cassava starch. The engineering properties of different commercial grades of sago, developed by roasting and steaming process were investigated. The physical properties (moisture content, size, shape (sphericity), bulk density, particle density, porosity), functional properties (solubility index, swelling power, cooking time, cooking loss, oil absorption index), pasting and dynamic rheological properties were studied. The size of the roasted commercial and steamed nylon sago varied from 3.57 to 4.11 mm and from 2.50 to 5.88 mm, respectively. The shape (sphericity) of different grades of sago ranged from 0.63 to 0.86. The bulk density and particle density of the different commercial and nylon sago varied from 420 kg m-3 to 800 kg m-3. The swelling power (39.59 g/g) of the steamed nylon sago was high as compared to that of roasted sago. The steamed nylon sago showed a reduction in peak viscosity, breakdown and final viscosity as compared with the roasted commercial sago. A decrease in cooking loss with an increase in cooking time was noticed in the roasted commercial sago, whereas increase in cooking loss with increase in cooking time was noticed in the steamed nylon sago. The elevated peak viscosity value showed reduction in pasting temperature for both steamed and roasted sago. The different grades of sago gel behaved like a dilute solution due to increase in loss modulus over storage modulus.