Life Sciences Commons^™

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

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

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. …

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, Spring 1920 to Summer 2023

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

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

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 revealed both species of …

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

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

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-1c Capsular Exopolysaccharide On Cheese Moisture Level, Deborah Low

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

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 …

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

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

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 and was …

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

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

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.

The Use Of Carnitine And Pyruvate In Weight Management, Karen Phyllis Bergs

Undergraduate Honors Capstone Projects

Carnitine has been a naturally occurring compound since the beginning of the century, and was considered to be an essential nutrient for quite some time. Carnitine has many essential roles in the body. Carnitine transports fatty acids into the mitochondria for energy, controls ketogenesis, and modulates the acyl-CoA/free CoA ratio. Studies have postulated that exercise decreases carnitine in the body, therefore leading to a deficiency in athletes. Carnitine has also been used as a weight loss product because of its fatty acid oxidation function. Many nutritional supplement companies have marketed on these functions of carnitine, resulting in a big business. …

Obesity: Environment Vs. Genetics, Kammi Marie Reeder Hansen

Undergraduate Honors Capstone Projects

The prevalence of overweight and obese individuals is rising. Between 1980 and 1990 there was an 8% increase in the prevalence of obesity. Obesity is associated with many diseases such as hypertension, type 2 diabetes, heart disease and cancer. Over $39 billion dollars is spent annually on the illnesses associated with obesity. Our American culture has been blamed for the rise in obesity, yet there are obviously many people living in the American culture that are not obese. Researchers have turned to genetics to explain this phenomenon. This article will examine the many environmental factors that contribute to obesity and …

Herbs: What Is My Choice?, Brooke Dipoma Bouwhuis

Undergraduate Honors Capstone Projects

Medicating oneself with herbal remedies has become and increasing popular phenomenon. It is estimated sales of herbal products were $3.2 million in 1997 (8). One third of educated, upper income Americans aged 25-49 years old are using these products each year (8). This paper is a compilation of information regarding the herbal industry. An overview of food and drug regulations as well as reviewing the 1994 Dietary Supplement Health Education Act clarify where industry is at today. A discussion regarding Germany's Commission E and their contribution to the herbal industry as well as reasons why the US is not following …

Syndrome X: A Review Of The Cluster Of Abnormalities, Diagnosis, And Treatment, Kathryn Lundgren Gurney

Undergraduate Honors Capstone Projects

Syndrome X is a cluster of abnormalities including insulin resistance, hypertension, dyslipidemia, upper-body obesity, increased levels of plasminogen activator inhibitor 1, decreased levels of tissue plasminogen activator, and hyperuricemia. The combined effect of these abnormalities greatly increases risk for Type 2 diabetes and coronary artery disease. Individuals at risk for Syndrome X are those with any of the abnormalities (not necessarily all) or with a family history of diabetes, hypertension, or early-onset coronary artery disease. Treatment of Syndrome X should be early and aggressive, starting with lifestyle changes. Exercise, proper diet, and weight loss all improve insulin resistance and thereby …

Antioxidants And Alcohol In The Progression Of Acquired Immunodeficiency Syndrome, Laura Lynne Prestwich

Undergraduate Honors Capstone Projects

Wasting syndrome in acquired immunodeficiency syndrome (AIDS) appears to play a role in decline of immune function. Along with poor appetite, HIV infected individuals seem to have a tendency to be heavy alcohol drinkers which may be immunosuppressive and cause malnutrition. Altered macronutrient metabolism visibly contributes to wasting; however, micronutrient deficiencies also appear to play a role. Micronutrient deficiency has also been known to decrease immune function. As part of their role as antioxidants, P-carotene, vitamin C, vitamin E, and selenium may be helpful in altering cell production and response to cytokines and other secretions. This may decrease viral replication …

Vegetarianism, Kimberly A. Folkman

Undergraduate Honors Capstone Projects

Although vegetarian eating has been around throughout recorded history, in recent years, interest in this eating style has gone up dramatically. As the number of individuals adopting vegetarian dietary practices increases, healthcare professionals are called upon to provide guidance and advice. It is the position of The American Dietetic Association that appropriately planned vegetarian diets are healthful, are nutritionally adequate, and provide health benefits in the prevention and treatment of certain diseases. Both vegetarian and nonvegetarian eating patterns can be healthful-or detrimental to your health. Studies indicate that vegetarians often have lower morbidity and mortality rates from several chronic degenerative …

Protein-Based Diets: Fact Or Fiction?, Melanie Douglass

Undergraduate Honors Capstone Projects

Protein-based diets are once again popular among the those vulnerable to quick weight loss schemes. Advocates for these diets claim quick, permanent weight loss, disease prevention, improved physical performance, and even enhanced mental productivity. It is claimed that a diet high in carbohydrate contributes to hyperinsulinemia, fat storage, and "bad" eicosanoid production among other things. However, the detrimental effect of a low carbohydrate, high protein diet is rarely discussed. Subjects who follow protein-based diets are prone to a state of ketosis, which causes them to lose an unhealthy amount of nutrients and water. In general the protein-based diets are a …

Targeting Minority Groups In Community Nutrition, Trisha Sisson Brimhall

Undergraduate Honors Capstone Projects

A community nutritionist takes on the immense task of "improving the nutrition, and ... health of individuals and groups within communities" (1). These objectives are generally met by private sector sponsors such as health care facilities, work-site wellness programs and food banks. If the arena of public health is included, then the dietitian's scope is enlarged to include federally-funded agencies designed to improve public health and disease prevention (1). Skills required of these community dietitians not only include clinical knowledge and assessment skills, but marketing, education, and research competencies. The challenges of community nutrition range from counseling an individual on …

The Maternal Diet Can Prevent Neural Tube Defects, Shannon Michelle Gardner

Undergraduate Honors Capstone Projects

Maternal diet and nutritional status have a direct impact on pregnancy course and outcome. Nutrition is critical to the development of the human embryo and fetus. Each year in the United States, approximately 4000 pregnancies are affected by neural tube defects (NTD). The most important finding in recent years has been the relationship between maternal folic acid status and NTDs. Other studies have found an association between zinc deficiency and an increased risk for having an NTD-affected pregnancy. Furthermore, some of the latest research has linked maternal obesity with the development of NTDs. The cumulative data from several studies have …

The Beneficial Effects Of Supplemental Vitamins C And E In Diabetic Subjects, Jessica Rupp Gibbons

Undergraduate Honors Capstone Projects

Few reviews have been written related to the benefits of supplementing vitamin C and E in diabetic individuals. Excessive protein glycosylation is seen in persons with diabetes, and vitamin E and C have been shown to be beneficial in decreasing the glycosylation of proteins. In addition, vitamins E and Care potent antioxidants and actively reduce oxidation, triglycerides, and free fatty acid levels in diabetics. Diabetics may benefit from supplementing vitamins E and C.

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 do they …

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 …