FLOW PROPERTIES OF LOW-MOISTURIZED STARCH MELTS AT AN ELEVATED-TEMPERATURE

The flow properties of starch melts (potato and corn starches) at the moisture content of 16, 20, 25, 30 and 35% (dry basis) were characteri zed using a capillary tube viscometer. By use of measured now rates (Q , m(3) s(-1)), and pressure drops of capillary tube (Delta P-c, MPa) a nd orifice (Delta P-o, MPa), the relationships between the flow rate a nd the pressure drop in the capillary tube (Delta P-d, MPa) were obtai ned. The flow curves of both starch melts showed good Linearly on loga rithmic scales. These starch melts, however, gave a yield stress, espe cially at low moisture content. Then bath flow curves satisfied an equ ation by Herschel-Bulkley power-law model after exchanging the flow ra te and the pressure drop to apparent shear rate ((gamma) over dot(a), s(-1)) and shear stress (tau(w), MPa), respectively. The flow properti es were good representative by Herschel-Bulkley power-law model and th ese curves varied with the moisture content. The flow properties betwe en potato and corn starch melts were different even though they were s ame moisture content, especially that was reflected in the consistency index.