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Full-Text Articles in Medicine and Health Sciences

Strain Hardening And Anisotropy During Tensile Testing Of Sheared Model Mozzarella Cheeses, Prateek Sharma, Peter A. Munro, Tzvetelin T. Dessev, Peter G. Wiles, E. Allen Foegeding Nov 2015

Strain Hardening And Anisotropy During Tensile Testing Of Sheared Model Mozzarella Cheeses, Prateek Sharma, Peter A. Munro, Tzvetelin T. Dessev, Peter G. Wiles, E. Allen Foegeding

Nutrition, Dietetics, and Food Sciences Faculty Publications

We studied the tensile fracture properties of model Mozzarella cheeses with varying amounts of shear work input (3.3–73.7 kJ/kg). After manufacture, cheeses were elongated by manual rolling at 65°C followed by tensile testing at 21°C on dumbbell-shaped samples cut both parallel and perpendicular to the rolling direction. Strain hardening parameters were estimated from stress–strain curves using 3 different methods. Fracture stress and strain for longitudinal samples did not vary significantly with shear work input up to 26.3 kJ/kg and then decreased dramatically at 58.2 kJ/kg. Longitudinal samples with shear work input <30 kJ/kg demonstrated significant strain hardening by all 3 estimation methods. At shear work inputs <30 kJ/kg, strong anisotropy was observed in both fracture stress and strain. After a shear work input of 58.2 kJ/kg, anisotropy and strain hardening were absent. Perpendicular samples did not show strain hardening at any level of shear work input. Although the distortion of the fat drops in the cheese structure associated with the elongation could account for some of the anisotropy observed, the presence of anisotropy in the elongated nonfat samples reflected that shear work and rolling also aligned the protein structure.


Effect Of Shear Work Input On Steady Shear Rheology And Melt Functionality Of Model Mozzarella Cheeses, Prateek Sharma, Peter A. Munro, Tzvetelin T. Dessev, Peter G. Wiles, Robert J. Buwalda Oct 2015

Effect Of Shear Work Input On Steady Shear Rheology And Melt Functionality Of Model Mozzarella Cheeses, Prateek Sharma, Peter A. Munro, Tzvetelin T. Dessev, Peter G. Wiles, Robert J. Buwalda

Nutrition, Dietetics, and Food Sciences Faculty Publications

Model Mozzarella cheeses with varied amounts of shear work input were prepared by working molten cheese mass at 70 °C in a twin screw cooker. Rheology and melt functionality were found to be strongly dependent on total shear work input. A non-linear increase in consistency coefficient (K from power law model) and apparent viscosity and decrease in flow behaviour index (n from power law model) were observed with increasing amounts of accumulated shear work, indicating work thickening behaviour. An exponential work thickening equation is proposed to describe this behaviour. Excessively worked cheese samples exhibited liquid exudation, poor melting and poor …


Pregenomic And Genomic Effects Of 24,25-Dihydroxyvitamin D3, Yang Zhang May 2015

Pregenomic And Genomic Effects Of 24,25-Dihydroxyvitamin D3, Yang Zhang

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

In the United States, the major dietary source of protein is poultry meat, particularly chicken. Phosphorus absorption in chickens is a critical problem in poultry production. It therefore is important to understand the cellular and molecular regulation of phosphorous absorption in intestine to increase efficiency of the process. This would provide the benefits of reducing feed costs and reducing phosphorous excretion, thereby contributing to the sustainability of agriculture in the United States. Therefore, the focus of this thesis is determining the effect of vitamin D metabolites involved in phosphate homeostasis using the chicken as a model.


Measurement Techniques For Steady Shear Viscosity Of Mozzarella-Type Cheeses At High Shear Rates And High Temperature, Prateek Sharma, Tzvetelin T. Dessev, Peter A. Munro, Peter G. Wiles, Graeme Gillies, Matt Golding, Bryony James, Patrick Janssen Mar 2015

Measurement Techniques For Steady Shear Viscosity Of Mozzarella-Type Cheeses At High Shear Rates And High Temperature, Prateek Sharma, Tzvetelin T. Dessev, Peter A. Munro, Peter G. Wiles, Graeme Gillies, Matt Golding, Bryony James, Patrick Janssen

Nutrition, Dietetics, and Food Sciences Faculty Publications

While measuring steady shear viscosity of Mozzarella-type cheeses in a rotational rheometer at 70 °C, three main difficulties were encountered; wall slip, structural failure during measurement and viscoelastic time dependent effects. Serrated plates were the most successful surface modification at eliminating wall slip. However, even with serrated plates shear banding occurred at higher shear rates. Because of the viscoelastic nature of the cheeses, a time dependent viscous response occurred at shear rates <1 >s−1, requiring longer times to attain steady shear conditions. Prolonged continuous shearing altered the structure of the molten cheeses. The effects of structural change were greatly reduced by …