Rheological characteristics of intermediate moisture blends of pregelatinized and raw wheat starch.
Rheological properties of intermediate moisture (35-45% wet basis) doughs from pregelatinized and raw wheat starch blends of various ratios were characterized using off-line capillary rheometry and online slit-die extrusion. In the case of capillary rheometer, viscosity of blends decreased by up to 50% as pregel starch concentration increased from 5 to 45%, whereas tests could not be conducted beyond 45% pregel starch concentration. For slit-die extrusion, viscosity was at a minimum at 60% pregel concentration, and it decreased by as much as 65% as pregel concentration increased from 0 to 60%. As pregel concentration increased (from 5 to 45% for the rheometer and from 0 to 60% for the extruder), the amount of water available in the system for gelatinization of existing raw starch granules decreased due to the stronger water-binding capacity of pregelatinized starch. This led to decreased additional conversion in the rheometer and extruder, which in turn caused a decrease in the volume fraction of starch and a reduction in viscosity.
Alavi
Sajid H
SH
Institute of Food Science, 151 Stocking Hall, Cornell University, Ithaca, New York 14853-7201, USA. salavi@wheat.ksu.edu
Chen
Kwan-Han
KH
Rizvi
Syed S H
SS
D005782:Gels; D008433:Mathematics; D012212:Rheology; D013213:Starch / Q000737:chemistry*; D013816:Thermodynamics; D014908:Triticum / Q000737:chemistry*; D014783:Viscosity
D005782:Gels; D013213:Starch