An Instron Universal testing machine and Differential Scanning Calorimetry were used to investiga... more An Instron Universal testing machine and Differential Scanning Calorimetry were used to investigate textural changes in cooked rice during storage. Two cells were used with the Instron for hardness measurement (Ottawa Texture Measuring System and Back Extrusion cells) and one cell for adhesion measurement (adhesion cell). During storage of cooked rice, retrogradation of the starch led to an increase in hardness as well as a decrease in the adhesion of cooked rice. Storage time, temperature and variety significantly influenced the hardness and adhesion of cooked rice. A correlation analysis between methods showed that Instron measurements OTMS and BE correlated better with a correlation coefficient of 0.978 than the two Instron methods and DSC with a correlation coefficient of 0.752.
A restructured potato model system was fried in canola oil for 5, 10, or 15 min at 170, 180, or 1... more A restructured potato model system was fried in canola oil for 5, 10, or 15 min at 170, 180, or 190C and tested in a Dynamic Mechanical Analyzer. Selected mechanical properties were measured using puncture and three-point bending cells. Forces involved in puncture were a combination of tension, compression, and shear, while the three-point bend test studied the crust flexural properties. Crust deformability seemed to be governed by internal structural yielding. Maximum force at rupture increased significantly with both frying time and temperature. Failure criteria identified and standardized types of failure observed during bending tests.
A restructured potato model system was fried for 5, 10 or 15 min at 170, 180, or 190C and tested ... more A restructured potato model system was fried for 5, 10 or 15 min at 170, 180, or 190C and tested in a dynamic mechanical analyzer. Stress relaxation phenomena was described by a two-element Maxwell model with a parallel spring. The viscoelastic behavior of the crust resulted from its porous structure of open and closed foam cells embedded in oil. Relaxation of stress in the fried crust was a result of slippage of the dispersed oil through the crust and from rearrangements of the air cells. Elastic modulus of the fried crust increased for higher frying times and temperatures and were the most significant elements in distinguishing between samples.
An Instron Universal testing machine and Differential Scanning Calorimetry were used to investiga... more An Instron Universal testing machine and Differential Scanning Calorimetry were used to investigate textural changes in cooked rice during storage. Two cells were used with the Instron for hardness measurement (Ottawa Texture Measuring System and Back Extrusion cells) and one cell for adhesion measurement (adhesion cell). During storage of cooked rice, retrogradation of the starch led to an increase in hardness as well as a decrease in the adhesion of cooked rice. Storage time, temperature and variety significantly influenced the hardness and adhesion of cooked rice. A correlation analysis between methods showed that Instron measurements OTMS and BE correlated better with a correlation coefficient of 0.978 than the two Instron methods and DSC with a correlation coefficient of 0.752.
A restructured potato model system was fried in canola oil for 5, 10, or 15 min at 170, 180, or 1... more A restructured potato model system was fried in canola oil for 5, 10, or 15 min at 170, 180, or 190C and tested in a Dynamic Mechanical Analyzer. Selected mechanical properties were measured using puncture and three-point bending cells. Forces involved in puncture were a combination of tension, compression, and shear, while the three-point bend test studied the crust flexural properties. Crust deformability seemed to be governed by internal structural yielding. Maximum force at rupture increased significantly with both frying time and temperature. Failure criteria identified and standardized types of failure observed during bending tests.
A restructured potato model system was fried for 5, 10 or 15 min at 170, 180, or 190C and tested ... more A restructured potato model system was fried for 5, 10 or 15 min at 170, 180, or 190C and tested in a dynamic mechanical analyzer. Stress relaxation phenomena was described by a two-element Maxwell model with a parallel spring. The viscoelastic behavior of the crust resulted from its porous structure of open and closed foam cells embedded in oil. Relaxation of stress in the fried crust was a result of slippage of the dispersed oil through the crust and from rearrangements of the air cells. Elastic modulus of the fried crust increased for higher frying times and temperatures and were the most significant elements in distinguishing between samples.
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