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Eakasit Sritham, Sundaram Gunasekaran
Rheological and Microstructure Evaluations of Amorphous Sucrose-Maltodextrin-Sodium Citrate Mixture

Appl. Rheol. 27:4 (2017) 43102 (10 pages)

Rheological properties and the mechanical relaxation behavior of rubbery amorphous sucrose-maltodextrin-sodium citrate systems were studied at room temperature using the small amplitude oscillatory shear test in the frequency range of 0.1 - 150 Hz. The system with high sucrose concentration exhibited viscous-dominant relaxation, while the system with high maltodextrin concentration exhibited elastic-dominant relaxation. The addition of sodium citrate could retard molecular mobility presumably due to its molecular interaction with sucrose rather than with maltodextrin. The technique was capable to detect changes in molecular process even with a small variation in the matrix components. Evidences obtained with scanning electron micrographs suggested the possible effect of sodium citrate to interfere with molecular interactions in the system with high maltodextrin concentration, i.e. the system tended to be more brittle.

Cite this publication as follows:
Sritham E, Gunasekaran S: Rheological and Microstructure Evaluations of Amorphous Sucrose-Maltodextrin-Sodium Citrate Mixture, Appl. Rheol. 27 (2017) 43102.

Mustapha M. Ould Eleya, Sundaram Gunasekaran
Rheology of fluid foods for dysphagic patients

Appl. Rheol. 17:3 (2007) 33137 (9 pages)

Pre-thickened beverages and barium sulfate suspensions are used in the treatment and diagnosis of dysphagia. These liquids are labeled nectar consistency (NC), honey consistency (HC) etc.These labels are rather misleading and do not represent the actual rheological character of the liquids.We carefully investigated the rheology of these liquids to assist both in their formulation and use for dysphagic patients. Steady state flow properties, thixotropy, dynamic response, and creep recovery behavior were investigated for six beverages and two barium sulfate suspensions. All samples exhibited a shear-thinning behavior. The flow curves of all samples followed both Herschel-Bulkley and Casson models. HC barium sulfate suspension exhibited higher yield stress, σ0, and higher storage modulus, G', than their fluid food counterparts. In contrast, NC barium sulfate suspension had lower σ0, and G' than some of the liquid food counterparts. Frequency spectra of NC samples were similar to that of a macromolecular solution with both G' and loss modulus, G'', increasing with frequency; whereas those of HC samples were similar to that of a gel with a little dependency of G' and G'' over frequency. Stress sweep experiments showed that the linear viscoelastic region of fluid foods and barium sulfate suspensions extended up to 1 and 10 Pa, respectively. Thus, significant differences exist in the rheological properties of both pre-thickened and videofluoroscopy fluids currently used for diagnosis and treatment of dysphagia.

Cite this publication as follows:
OuldEleya MM, Gunasekaran S: Rheology of fluid foods for dysphagic patients, Appl. Rheol. 17 (2007) 33137.

Won B. Yoon, Sundaram Gunasekaran, Jae W. Park
Evaluating viscosity of Surimi paste at different moisture contents

Appl. Rheol. 14:3 (2004) 133-139

The steady and dynamic shear viscosity of fish muscle protein paste obtained from Alaska pollock surimi at 95%, 90%, 85%, 80%, and 75% of moisture contents were measured in the temperature range of 5°C to 20°C. To estimate the steady shear viscosity at high shear rate from dynamic shear viscosity, the modified Cox-Merz rule was applied by introducing a frequency shift factor. The concentration dependence of zero-shear viscosity showed power-law dependence with an exponent of 3.5, and the universal behavior of viscosity at different protein concentrations was observed by a introducing reduced variables. The Carreau model was applied to describe the shear- thinning behavior of the surimi paste, and the model parameters estimated empirically showed moisture content dependence. The viscous flow behavior was independent of temperature (5°C to 20°C), and addition of starch decreased the flow index and viscosity of the paste, compared to the pure surimi paste.

Cite this publication as follows:
Yoon WB, Gunasekaran S, Park JW: Evaluating viscosity of Surimi paste at different moisture contents, Appl. Rheol. 14 (2004) 133.

Y.-C. Wang, S. Gunasekaran, A.J. Giacomin
The Lodge Rubberlike Liquid Behavior for Cheese in Large Amplitude Oscillatory Shear

Appl. Rheol. 11:6 (2001) 312-319

The viscoelasticity of reduced-fat Cheddar and Mozzarella cheeses was characterized in small (parallel disk rheometer, go = 0.01) and large (sliding plate rheometer, 0.2< go <7) amplitude oscillatory shear at 40 and 60 C. We deduced the linear relaxation spectrum from the small strain measurements. At large strain amplitudes, we found sinusoidal stress responses whose amplitudes are well below those predicted from the linear relaxation spectrum, and yet remarkably linear with strain amplitude. We call this the large strain linear regime. We discovered that the Lodge rubberlike liquid can quantitatively explain the large strain linear regime if we scale down the relaxation moduli in the linear spectrum by a constant. This large strain linear regime persists to much higher strain amplitudes for Cheddar (go <= 4) than for Mozzarella (go <= 1). This is perhaps due to oriented structure of the protein matrix in the Mozzarella cheese.

Cite this publication as follows:
Wand YC, Gunasekaran S, Giacomin AJ: The Lodge Rubberlike Liquid Behavior for Cheese in Large Amplitude Oscillatory Shear, Appl. Rheol. 11 (2001) 312.

Chenxu Yu, Sundaram Gunasekaran
Correlation of dynamic and steady viscosities of food materials

Appl. Rheol. 11:3 (2001) 134-140

Eight commercial foods representing a wide range of viscosities (i.e. honey, condensed milk, mayonnaise, tomato ketchup, cream cheese, yogurt, process and Mozzarella cheeses) were investigated. Their steady shear viscosity and dynamic complex viscosity were determined by rheological measurements at two temperatures using a Bohlin-CVO rheometer. Based on experimental data, shear rate dependence of steady flow apparent viscosity and frequency dependence of dynamic viscosity was established and compared. It was determined that for condensed milk, tomato ketchup and mayonnaise, a modified Cox-Merz relation could be established. For cream cheese, a generalized Cox-Merz relation was proposed; and for yogurt, a deviation from the Cox-Merz rule was found. For Mozzarella and process cheeses a sharp drop in steady shear viscosity was noticed between 1~10 s-1 shear rate range. The Cox-Merz rule was not applicable for these cheese samples.

Cite this publication as follows:
Yu C, Gunasekaran S: Correlation of dynamic and steady viscosities of food materials, Appl. Rheol. 11 (2001) 134.

M. Mehmet Ak and Sundaram Gunasekaran
Simulation of lubricated squeezing flow of a Herschel-Bulkley fluid

Appl. Rheol. 10:6 (2000) 274-279

Cite this publication as follows:
Ak MM, Gunasekaran S: Simulation of lubricated squeezing flow of a Herschel-Bulkley fluid, Appl. Rheol. 10 (2000) 274.


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