Author
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Meadows, Frederick |
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Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 2/1/2002 Publication Date: 7/31/2002 Citation: N/A Interpretive Summary: Rapid Visco Analysis has been used to assess the rheological properties in rice flour. However, little is known about the relationships between the pasting characteristics and rice composition. This information is needed to target genes and growth environments necessary for value-added qualities. We have implemented the first derivative of viscograms as a means to determine the relationship between pasting rates with respect to time, starch, and proteins in rice flour. Our approach provides the details needed to determine the role of specific constituents in rice flour pasting. Technical Abstract: The objective of these studies was to gain a better understanding of pasting processes in rice. We chose 6 different medium grain rice samples with amylose contents varying from 0.41 to 24.9% and protein varying from 4.89 to 10.65%. By using the first derivative of rapid visco analyzer (RVA) curves, the rates at which pasting proceeds could be obtained. We found that CM101 (CA) containing the lowest amylose content (0.41%) and 7.04% protein exhibited a single smooth transition during pasting. All other samples, M201 (TX), Nato (LA), Koshihikari (CA), Mercury (LA), and Nanking Sel (LA) with higher amylose contents underwent multiple transitions and rate changes prior to reaching the peak viscosity. Disruption of disulfide linkages using dithiothreitol (DTT) led to a decrease in the rate of the single pasting step observed for CM101 (CA). Rice containing larger concentrations of amylose showed an increase in the first, but a decrease in subsequent steps. Our data suggests that amylopectin and protein are mutually important in the initialization of pasting and textural properties in grains. At later stages of pasting, amylose and its complexes seem to become important in the solubilization of granular constituents. |
