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Food Science

Nutrition, Dietetics, and Food Sciences Faculty Publications

2015

Articles 1 - 8 of 8

Full-Text Articles in Life 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.

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Growth And Gas Formation By Lactobacillus Wasatchensis, A Novel Obligatory Heterofermentative Nonstarter Lactic Acid Bacterium, In Cheddar-Style Cheese Made Using A Streptococcus Thermophilus Starter, Western Dairy Center, Utah State University, Megan Jane Ostler, Jeff Broadbent, Craig J. Oberg, Donald J. Mcmahon Nov 2015

Growth And Gas Formation By Lactobacillus Wasatchensis, A Novel Obligatory Heterofermentative Nonstarter Lactic Acid Bacterium, In Cheddar-Style Cheese Made Using A Streptococcus Thermophilus Starter, Western Dairy Center, Utah State University, Megan Jane Ostler, Jeff Broadbent, Craig J. Oberg, Donald J. Mcmahon

Nutrition, Dietetics, and Food Sciences Faculty Publications

A novel slow-growing, obligatory heterofermentative, nonstarter lactic acid bacterium (NSLAB) Lactobacillus wasatchensis WDC04 was studied for growth and gas production in Cheddar-style cheese made using Streptococcus thermophilus as the starter culture. Cheesemaking trials were conducted using St. thermophilus alone or in combination with Lb. wasatchensis deliberately added to cheese milk at a level of ~104 cfu/ml. Resulting cheeses were ripened at 6 or 12°C. At d 1, starter streptococcal numbers were similar in both cheeses (~109 cfu/g) and fast-growing NSLAB lactobacilli counts were below detectable levels (<102 cfu/g). As expected, Lactobacillus wasatchensis counts were 3 x 10 …

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Transcriptome Analysis Of Bifidobacterium Longum Strains That Show A Differential Response To Hydrogen Peroxide Stress, Taylor S. Oberg, Robert E. Ward, James L. Steele, Jeff Broadbent Oct 2015

Transcriptome Analysis Of Bifidobacterium Longum Strains That Show A Differential Response To Hydrogen Peroxide Stress, Taylor S. Oberg, Robert E. Ward, James L. Steele, Jeff Broadbent

Nutrition, Dietetics, and Food Sciences Faculty Publications

Consumer and commercial interest in foods containing probiotic bifidobacteria is increasing. However, because bifidobacteria are anaerobic, oxidative stress can diminish cell viability during production and storage of bioactive foods. We previously found Bifidobacterium longum strain NCC2705 had signifi- cantly greater intrinsic and inducible resistance to hydrogen peroxide (H2O2) than strain D2957. Here, we explored the basis for these differences by examining the transcriptional responses of both strains to sub-lethal H2O2 exposure for 5- or 60-min. Strain NCC2705 had 288 genes that were differentially expressed after the 5-min treatment and 114 differentially expressed genes …

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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 …

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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 …

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Growth And Gas Production Of A Novel Obligatory Heterofermentative Cheddar Cheese Nonstarter Lactobacilli Species On Ribose And Galactose, Western Dairy Center, Utah State University, Megan Jane Ostler, Jeff Broadbent, Craig J. Oberg, Donald J. Mcmahon Jan 2015

Growth And Gas Production Of A Novel Obligatory Heterofermentative Cheddar Cheese Nonstarter Lactobacilli Species On Ribose And Galactose, Western Dairy Center, Utah State University, Megan Jane Ostler, Jeff Broadbent, Craig J. Oberg, Donald J. Mcmahon

Nutrition, Dietetics, and Food Sciences Faculty Publications

An obligatory heterofermentative lactic acid bacterium, Lactobacillus wasatchii sp. nov., isolated from gassy Cheddar cheese was studied for growth, gas formation, salt tolerance, and survival against pasteurization treatments at 63°C and 72°C. Initially, Lb. wasatchii was thought to use only ribose as a sugar source and we were interested in whether it could also utilize galactose. We conducted experiments to determine the rate and extent of growth and gas production in carbohydraterestricted (CR) de Man, Rogosa, and Sharpe (MRS) medium under anaerobic conditions with various combinations of ribose and galactose at 12, 23, and 37°C, with 23°C being the optimum …

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Gas-Forming Nonstarter Lactorbacilli, Megan Jane Ostler, Jeff Broadbent, Craig J. Oberg, Donald J. Mcmahon Jan 2015

Gas-Forming Nonstarter Lactorbacilli, Megan Jane Ostler, Jeff Broadbent, Craig J. Oberg, Donald J. Mcmahon

Nutrition, Dietetics, and Food Sciences Faculty Publications

An obligatory heterofermentative lactic acid bacterium Lactobacillus wasatchii sp. nov. isolated from gassy Cheddar cheese was studied for growth, gas formation, salt tolerance and survival against pasteurization treatments at 63°C and 72°C. Initially, Lb. wasatchii was thought to only use ribose as a sugar source and we were interested in whether it could utilize galactose. Experiments to determine rate and extent of growth and gas production in carbohydrate restricted (CR) de Man, Rogosa, and Sharpe (MRS) medium under anaerobic conditions with various combinations of ribose and galactose at 12, 23, and 37°C were conducted with 23°C being the more optimum …

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Growth Inhibitory Properties Of Lactose Fatty Acid Esters, Seung-Min Lee, Guneev Sandhu, M. K. Walsh Jan 2015

Growth Inhibitory Properties Of Lactose Fatty Acid Esters, Seung-Min Lee, Guneev Sandhu, M. K. Walsh

Nutrition, Dietetics, and Food Sciences Faculty Publications

Sugar esters are biodegradable, nonionic surfactants which have microbial inhibitory properties. The influence of the fatty acid chain length on the microbial inhibitory properties of lactose esters was investigated in this study. Specifically, lactose monooctanoate (LMO), lactose monodecanoate (LMD), lactose monolaurate (LML) and lactose monomyristate (LMM) were synthesized and dissolved in both dimethyl sulfoxide (DMSO) and ethanol. Minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) were determined in growth media. LML was the most effective ester, exhibiting MIC values of

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