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Full-Text Articles in Life Sciences

Establishing Threshold Levels Of Nitrite Causing Pinking Of Cooked Meat, Kevin M. Heaton May 1998

Establishing Threshold Levels Of Nitrite Causing Pinking Of Cooked Meat, Kevin M. Heaton

All Graduate Theses and Dissertations

Sporadic problems with pink color defect, or pinking, has occurred in cooked meat products for decades. Pink color can be due to the presence of undenatured myoglobin, denatured globin hemochromes, or nitrosylhemochrome. This research documented the level of added nitrite that produced nitrosylhemochrome in processed meat rolls from fabricated beef round, pork shoulder, turkey breast, and chicken breast. For each meat type, preliminary studies were conducted to narrow the range at which added nitrite caused pinking. Subsequently, the nitrite levels were increased incrementally by 1-ppm, and pink color was measured by trained panelists and by a Hunter color meter. Nitrosylhemochrome ...


Influence Of Streptococcus Thermophilus Mr-1 C Capsular Exopolysaccharide On Cheese Moisture Level, Deborah Low May 1998

Influence Of Streptococcus Thermophilus Mr-1 C Capsular Exopolysaccharide On Cheese Moisture Level, Deborah Low

All Graduate Theses and Dissertations

This study investigated the role of exopolysaccharide (EPS) in cheese moisture retention. Analysis of low-fat Mozzarella cheese made with different combinations of EPS-producing (Streptococcus thermophilus MR-1C and Lactobacillus delbrueckii ssp. bulgaricus MR-lR) and non-EPS-producing (S. thermophilus TA061 and L. helveticus LH100) starters showed significantly higher moisture levels in cheese made with S. thermophilus MR-1C. To determine if the S. thermophilus MR-1C EPS was responsible for increased moisture retention, gene replacement was used to inactivate the epsE gene in this bacterium. Low-fat Mozzarella cheese made with L. helveticus LH100 plus the EPS-negative mutant, S. thermophilus DM1O, had significantly lower moisture content ...


Study Of Ripening Characteristics Of Full-Fat And Low-Fat Cheddar Cheese Using Fourier Transform Infrared Spectroscopy And Texture Analyzer, Manxiang Chen May 1998

Study Of Ripening Characteristics Of Full-Fat And Low-Fat Cheddar Cheese Using Fourier Transform Infrared Spectroscopy And Texture Analyzer, Manxiang Chen

All Graduate Theses and Dissertations

A suitable microtome sampling technique was used to sample cheese for analysis using FTIR spectroscopy. Well-separated fat- and protein-related bands were obtained in the spectra of Cheddar and Mozzarella cheese samples using this method. The absorbance intensity of the spectra was proportional to the thickness of the sample. The intensity of absorbance and fat- and protein-related bands increased with an increase in the fat and protein content in the sample. Strong and well-separated bands at 1744, 1450, 1240, 1170, and 1115 cm-1 arising mainly from fat content were observed using this method. Bands observed at 1650 and 1540 cm ...


Tryptophan Catabolism By Lactobacillus Spp. : Biochemistry And Implications On Flavor Development In Reduced-Fat Cheddar Cheese, Sanjay Gummalla May 1998

Tryptophan Catabolism By Lactobacillus Spp. : Biochemistry And Implications On Flavor Development In Reduced-Fat Cheddar Cheese, Sanjay Gummalla

All Graduate Theses and Dissertations

Amino acids derived from the degradation of casein in cheese serve as precursors for the generation of key flavor compounds. Microbial degradation of tryptophan (Trp) is thought to promote formation of aromatic compounds that impart putrid fecal or unclean flavors in cheese, but pathways for their production have not been established. This study investigated tryptophan catabolism by Lactobacillus casei LC301 and LC202 and Lactobacillus helveticus CNRZ32 and LH212 cheese flavor adjuncts in carbohydrate starvation (pH 6.5, 30 or 37°C, no sugar) and cheese-like conditions (pH 5.2, 4% NaCl, 15°C, no sugar). Enzyme assays of cell-free extracts ...


Characterization Of The Proteolytic System In Lactococcus Lactis Starter Cultures, Christina Beer May 1998

Characterization Of The Proteolytic System In Lactococcus Lactis Starter Cultures, Christina Beer

All Graduate Theses and Dissertations

The proteolytic system of Lactococcus lactis starter cultures influences both flavor and the characteristic body and texture of cheese. The ability to further understand and control how different components of this proteolytic system work together to hydrolyze milk proteins would be of immense importance to the dairy industry.

The goal of this research was to characterize Lactococcus lactis subsp. lactis starter bacteria with varying prt operon compositions by proteinase specificity, aminopeptidase and lipase activities, growth, and influence on cheese flavor. By using a cheese slurry system, a statistical model to predict milk protein hydrolysis patterns was developed.

Lactococcus lactis subsp ...


Expression And Iron Loading Of Recombinant Ferritin Homopolymers, Jia-Hsin Guo May 1998

Expression And Iron Loading Of Recombinant Ferritin Homopolymers, Jia-Hsin Guo

All Graduate Theses and Dissertations

Ferritin is an iron storage protein consisting of H and L chains to form a 24-subunit heropolymer. Ceruloplamin oxidizes Fe(II) and then loads the iron into ferritin. This research was conducted to determine which ferritin subunit is involved and whether a proposed iron-loading channel is required for iron loading by ceruloplasmin.

Recombinant rat liver H and L chain ferritin homopolymers, designated as rH-Ft and rL-Ft, respectively, were produced using insect cell-baculovirus and Escherichia coli expression systems. The expressed rH-Ft strongly suppressed the growth of the host. The rH-Ft expressed in the E. coli contained approximately 150 iron atoms/ferritin ...


Influence Of Stress Treatments On The Resistance Of Lactococcus Lactis To Freezing And Freeze-Drying, Chan Lin May 1998

Influence Of Stress Treatments On The Resistance Of Lactococcus Lactis To Freezing And Freeze-Drying, Chan Lin

All Graduate Theses and Dissertations

This study investigated the effect of cold, heat, or osmotic shock treatment on the resistance of L. lactis subsp. cremoris MM160 and MM310 and Lactococcus lactis subsp. lactis MM210 and FG2 cheese starter bacteria to freezing and freeze-drying. The ability to withstand freezing at -60°C for 24 h was variable among lactococci, but resistance to this treatment was significantly improved (P < 0.05) in most strains by a 2-h cold shock at l0°C or a 25-min heat shock at 39°C (L. lactis subsp. cremoris) or 42°C (L. lactis subsp. lactis). Stress treatments that improved lactococcal freeze resistance were also found to significantly (P < 0.05) enhance the resistance of most strains to lyophilization. Increased resistance to freezing or lyophilization was not detected when stress treatments were performed in broth that contained erythromycin, which indicated stress-inducible proteins were involved in cell protection. Membrane fatty acid analysis of stress-treated cells suggested that enhanced resistance to freezing and lyophilization may be related to heat or cold shock-induced changes in cell membrane composition. Heat-shocked cells had a higher 19:0 cyclopropane fatty acid content than did control cells, and cold-shocked cells contained a lower ratio of saturated to unsaturated fatty acids. Other factors must also be involved in cell protection, however, because similar changes in membrane composition were also detected in strains whose resistance to freezing and lyophilization was not improved by heat or cold shock.


Soy Isoflavones: Database Development, Estrogenic Activity Of Glycitein And Hypocholesterolemic Effect Of Daidzein , Tongtong Song Jan 1998

Soy Isoflavones: Database Development, Estrogenic Activity Of Glycitein And Hypocholesterolemic Effect Of Daidzein , Tongtong Song

Retrospective Theses and Dissertations

Soy isoflavones are proposed to have certain health protective activities, including prevention of cancer, lowering blood cholesterol levels and reducing postmenopausal bone loss. To evaluate the health-enhancing properties of isoflavones, a stable and inexpensive source of these compounds is necessary. Chemical synthesis is a practical way to obtain pure isoflavones. The synthesis of daidzein was modified to a simple, fast and high yield method by cyclizing 2,4,4'-trihydroxydeoxybenzoin (THB) with boron trifluoride etherate and methanesulphonyl chloride. The yield was >86%, and the purity of synthesized daidzein was >98%. The intermediate of daidzein synthesis, THB, with a similar structure ...


Phospholipid Fatty Acid Composition Of Modified Soybeans And The Effect Of Saturated Fatty Acid Content On Seed Performance , Tong Wang Jan 1998

Phospholipid Fatty Acid Composition Of Modified Soybeans And The Effect Of Saturated Fatty Acid Content On Seed Performance , Tong Wang

Retrospective Theses and Dissertations

Soybeans with a wide range of oil compositions were analyzed for their phospholipid (PL) fatty acid composition and stereospecific distribution. PLs were a minor component of soybean seed, comprising an average of 0.9% of the seed, which was an equivalent of 3.7% of the crude soybean oil. Phosphatidylcholine (PC), phosphatidylethanolamine (PE) and phosphatidylinositol (PI) were the major PL classes, with relative proportions of 55.3, 26.3, and 18.4%, respectively. These proportions were affected by the changes in oil fatty acid composition. The fatty acid composition of PLs changed with oil fatty acid modification. Stereospecific analysis showed ...


Mutational Analysis Of Aspergillus Awamori Glucoamylase Selectivity To Improve Glucose Yield , Hsuan-Liang Liu Jan 1998

Mutational Analysis Of Aspergillus Awamori Glucoamylase Selectivity To Improve Glucose Yield , Hsuan-Liang Liu

Retrospective Theses and Dissertations

Three single mutations, Lys108→Arg, Lys108→Met and Tyr312→Trp, and one insertional mutation, 322-314 Loop, in Aspergillus awamori glucoamylase were constructed and tested along with four previously constructed thermostable mutations: Asn20→Cys/Ala27→Cys (SS), Ser30→Pro, Gly137→Ala, and Ser436→Pro, and one previously made thermosensitive mutation, Ala27→Pro, for their selectivity by high-concentration glucose condensation and maltodextrin hydrolysis reactions. Lys108 is important in substrate binding during maltooligosaccharide hydrolysis. Both SS and 311-314 Loop mutant GAs successfully decrease isomaltose formation rate and thus increase peak glucose yield. Tyr312→Trp GA helps to form a tighter hydrogen bond network ...


Effects Of Ionizing Radiation On Pork, Beef, And Turkey Quality , Kevin Eugene Nanke Jan 1998

Effects Of Ionizing Radiation On Pork, Beef, And Turkey Quality , Kevin Eugene Nanke

Retrospective Theses and Dissertations

Color changes observed in irradiated meat were found to be species- and package-type dependent. Irradiated vacuum-packaged (VP) pork and turkey became redder following to irradiation relative to unirradiated controls. However, irradiated VP beef decreased in redness as compared to unirradiated controls. In contrast, aerobically-packaged (AP) pork and beef became less red as a result of irradiation compared to unirradiated controls. Whereas, redness values of irradiated AP turkey increased due to irradiation. Redness values of the VP pork and turkey were unchanged during 12 and 10 wks, respectively, of display, but decreased for VP beef and all AP samples during display ...


Assessment Of Intramuscular Fat, Lean Growth, And Lean Composition Using Real-Time Ultrasound , Kevin Duane Ragland Jan 1998

Assessment Of Intramuscular Fat, Lean Growth, And Lean Composition Using Real-Time Ultrasound , Kevin Duane Ragland

Retrospective Theses and Dissertations

Real-time ultrasonic measurements were collected on live animals as part of two studies. The first study (n = 300) was designed to evaluate the use of real-time ultrasound to predict intramuscular fat in the longissimus muscle of live swine. The purpose of the second study (n = 240) was to assess the accuracy of serial real-time ultrasonic measurements of loin muscle and fat thickness for determining carcass lean and lean of the major primal cuts. In the first study, a cross-sectional and longitudinal image was collected on each animal. The cross-sectional image was used felt determining backfat and loin muscle area. The ...


Petfood: Physico-Chemical Characteristics And Functional Properties Of Meat By-Products And Mechanically Separated Chicken (Msc) In A High-Moisture Model System , José Antonio Rivera Jan 1998

Petfood: Physico-Chemical Characteristics And Functional Properties Of Meat By-Products And Mechanically Separated Chicken (Msc) In A High-Moisture Model System , José Antonio Rivera

Retrospective Theses and Dissertations

Two studies were conducted to determine the physico-chemical characteristics and functional properties of selected pork and poultry by-products used in the formulation of high-moisture petfood;In the first study, pork by-products (lung lobes, kidneys), chicken viscera (head, feet and viscera) and MSC were evaluated for proximate composition, protein distribution and connective tissue. Proximate composition varied among meat by-products and MSC. Pork by-products contained the highest level of crude protein (p 0.05) affected by salt (2%), phosphate (0.3%) or NaOH (0.075%). Chicken viscera had the lowest (p < 0.05) mean texture measurements among the meat by-products and MSC. Strong negative correlations (p < 0.05) were obtained for texture with total collagen, soluble collagen and high ionic strength soluble (HIS) proteins;Additional research is warranted to determine if texture and % WRC are significantly improved by the addition of MSC to mixtures of pork and poultry by-products in combination with inorganic salts.


Inferring Bread Doneness With Air-Pulse/Ultrasonic Ranging Measurements Of The Loaf Elastic Response , Loren Elbert Faeth Jan 1998

Inferring Bread Doneness With Air-Pulse/Ultrasonic Ranging Measurements Of The Loaf Elastic Response , Loren Elbert Faeth

Retrospective Theses and Dissertations

This research marks the discovery of a method by which bread doneness may be determined based on the elastic properties of the loaf as it bakes. The purpose of the study was to determine if changes in bread characteristics could be determined by non-contact methods during baking, as the basis for improved control of the baking process. Current control of the baking process is based on temperature and dwell time, which are determined by experience to produce a produce which is approximately "done." There is no direct measurement of the property of interest, doneness;An ultrasonic measurement system was developed ...


Effects Of Ultra High Hydrostatic Pressure On The Structure And Properties Of Starches, Herman Katopo Jan 1998

Effects Of Ultra High Hydrostatic Pressure On The Structure And Properties Of Starches, Herman Katopo

Retrospective Theses and Dissertations

The structures and physical properties of ultra high hydrostatic pressurized starches were investigated. Six starches were used: normal maize, waxy maize, high amylose maize (70%), tapioca, potato, and rice. Each starch was pressurized in powder form, in 1:1 (v/w) ethanol:starch suspension, in 1:1 and 2:1 (v/w) water:starch suspension, for 5 minutes and 1 hour dwelling time at 100,000 Psi. Pasting and thermal properties were measured by using a rapid visco analyzer and a differential scanning calorimeter, respectively. The molecular weight distribution was analyzed using gel permeation chromatography with Sepharose CL2B gel followed ...


A Tale Of Two Chickens: Exploring The Social And Economic Implications Of Our Food Choices, Laura Bainbridge Jan 1998

A Tale Of Two Chickens: Exploring The Social And Economic Implications Of Our Food Choices, Laura Bainbridge

Presidential Scholars Theses (1990 – 2006)

A century ago chicken was considered a luxury item. In fact, people would eat steak or lobster when they could not afford chicken and ladies' magazines advised on how to substitute veal for chicken in recipes (Gordon, 1996). In 1928, President Hoover promised "a chicken in every pot", but it was not until the 1960's that the poultry industry really took off. Today, there are 15 chickens in every pot; the average American consumes 71.8 pounds of broiler meat annually (Oberholtzer, 1997). Where does all of this chicken come from? Who grows the chicken we eat and how ...


Purification, Characterization And Kinetic Studies Of Antinutrients In Bambara Groundnut (Vigna Subterranea (L.) Verdc.) Seeds , Redempta Boy Kegode Jan 1998

Purification, Characterization And Kinetic Studies Of Antinutrients In Bambara Groundnut (Vigna Subterranea (L.) Verdc.) Seeds , Redempta Boy Kegode

Retrospective Theses and Dissertations

The bambara groundnut (Vigna subterranea (L.) Verdc.) is an indigenous African legume crop that is grown for human consumption of its seed. A proanthocyanidin (PA) has been purified and characterized from the hulls of bambara groundnut seed by extraction of the hulls with aqueous acetone, chromatography on Sephadex LH-20, resulting in a pure PA with a degree of polymerization of six. Spectral analysis and 13C NMR determined that the PA was a dihydroflavanol. The purified PA was used as the standard in subsequent tannin assays where eight different bambara groundnut seed samples were assayed for tannin using four different tannin ...


Variety Effect On Free Fatty Acid Development And Co2 Production In Stored Soybeans, Dmitro Zagrebenyev Jan 1998

Variety Effect On Free Fatty Acid Development And Co2 Production In Stored Soybeans, Dmitro Zagrebenyev

Retrospective Theses and Dissertations

Stored soybeans are subject to deterioration. Free Fatty Acid development in soybean oil is always known to accompany the deterioration. Storage fungi is the major factor causing soybean deterioration that can bring substantial losses to processors. Different varieties may have different resistance to the development of all or some fungi. Samples of popular soybean varieties were hand harvested and stored at 22% moisture content and temperature 26 C. No differences were found in C02 evolution. Significant differences were found in FFA development among three varieties.


Detection Of Rancidity In Peanuts, Sophe Williamson Jan 1998

Detection Of Rancidity In Peanuts, Sophe Williamson

Theses : Honours

As peanuts age, the lipid component deteriorates, and the peanuts become rancid. The Health Department of Western Australia has received numerous complaints from consumers who are unsatisfied with the quality of peanuts they have purchased from certain grocers. Presently there is no standard methodology for detecting rancidity m peanuts, thus enabling grocers to continue selling peanuts of poor quality. In an attempt to overcome this problem, a standardised methodology needs to be developed, which will enable offending grocers to be prosecuted The three methodologies trialed were the Peroxide Value (PV), Acid Value (AV), and Fatty Acid Profile (FAP) methods. In ...