Master of Science / Food Science - Animal Sciences & Industry / Fadi Aramouni / Blue-green pigments have the ability to form in crushed and whole garlic cloves following a rapid series of enzymatic and non-enzymatic reactions. Economic losses associated with a reduction in organoleptic quality of garlic (Allium sativum L.) containing blue-green pigments can be incurred. Preventing blue-green pigment formation can mitigate potential financial and brand equity damages. To prevent pigment formation, inactivation of the enzyme which yields pigment substrates is essential. Two methods to inactivate the enzyme associated with pigment formation were explored: blanch treatment of whole garlic cloves (100°C, 5 min); and soaking of whole, non-blanched garlic cloves in low pH (<3.0) acetic or citric acid pickling solutions for seven days. The blanching treatment was effective in inactivating the enzyme as the pigment substrate decreased by approximately 99% as compared with pigment substrate concentrations in non-blanched garlic cloves. Soaking whole garlic cloves in low pH (<3.0) pickling solutions did not result in enzyme inactivation as pigments formed in cloves soaked in the acetic acid pickling solutions; however pigments did not form in cloves soaked in the citric acid pickling solution. This may be due to the different effect mono- and poly-carboxylic acids have on the permeability of garlic cell membranes. Blanching garlic cloves can be implemented as a processing step to prevent pigment formation. Soaking garlic in a low pH pickling solution comprised of a poly-carboxylic acid does not inactivate the enzyme associated with pigment formation but pigment formation can be prevented. Other methods presented in the literature to prevent pigment formation include controlling growth, harvest and storage conditions, as well as treating garlic clove homogenates with chemical additives.

Master of Science / Department of Food Science / Elizabeth Boyle / Salmonellosis is one of the most important bacterial foodborne infections in the United States resulting in over 1 million illnesses and 375 deaths annually. Salmonella serotypes cause several types of disease in humans: gastroenteritis, enteric fever, septicemia, focal infections, and an asymptomatic carrier state. Salmonella-shedding pigs are known to constitute a risk factor for contamination of carcasses during the slaughter process. Vaccination has generally not been effective in the prevention of Salmonella, partially because of the rapid mutation rate. Previous research has indicated that >70% of farms tested in Iowa were positive for Salmonella during 2006-2009. Salmonella-colonized pigs are usually asymptomatic carriers of the bacterium and can shed upon exposure to stress causing contamination of pen-mates, trailers used for shipping, and lairage areas at processing facilities. Emergence and dissemination of antimicrobial-resistant pathogens, which antibiotics are commonly used in pig production, have become a public health concern worldwide. For this reason, alternative interventions need to be evaluated for effectiveness. The objective of this report was to determine if there is a genetic basis for host resistance or susceptibility to Salmonella through quantitative and/or molecular selection. Genetic improvement of disease resistance and/or tolerance in animals is a potentially effective intervention for addressing pre-harvest food safety issues. Previous research has demonstrated genetic control of the immune response to pathogens. Developing a strong innate response to infection, so the animal does not become ill or become a carrier, is the basis for a genetic intervention for Salmonella. Quantitative trait loci for humoral and innate immune response have been detected for E. coli through leucocyte counts, cytokine concentration, mitogen-induced proliferation, and levels of pre-infection antibody titers. Single nucleotide polymorphisms have been found and can be exploited for genetic improvement of the innate immune response in pigs when infected with Salmonella. Pigs that differentially express polymorphisms and persistently shed the bacteria versus pigs that do not shed or shed little can be used as criteria for selection when developing the intervention.

Master of Science / Food Science / J. Scott Smith / The objective of this study was to observe the effect of natural cocoa powder versus 200 ppm of tocopherols on delaying the onset of oxidative rancidity in peanuts, peanut butter, and peanut oil. The samples were obtained from a single lot of blended Runner peanuts after roasting, grinding, and pressing. The samples were treated within a week of initial roasting with either 200 ppm of mixed tocopherols or 2.5% cocoa powder. The development of oxidation was monitored by peroxide value (PV) and gas chromatography monitoring of hexanal development. The peanut butter samples were assessed by a professional sensory panel using descriptive analysis for the development of rancidity. The data was analyzed using JMP SAS software. In peanuts, the cocoa powder sample developed significantly lower levels of oxidation identifiers than the tocopherol or control samples. In peanut oil, there was no significant difference in levels of oxidation identifiers between the treatments. In peanut butter, the PV was significantly higher in the tocopherol sample than the cocoa powder or control samples, but no significant difference was observed in hexanal. The results of the sensory analysis indicated that the cocoa powder depressed the perception of both positive and negative attributes compared to the tocopherol and control samples. This study showed that cocoa powder may be a more effective preservative than an untreated sample or a sample treated with 200 ppm of tocopherols in peanuts and peanut butter; however, cocoa powder at 2.5% w/w basis did not perform as a significant antioxidant in peanut oil.

Master of Science / Department of Food Science / Edgar Chambers IV / Sparkling wines represent an important part of the full wine category. Currently, no lexicon exists that includes aroma, flavors, and mouthfeel for sparkling wine. The objectives of this research were to:1) develop an aroma, flavor, taste and mouthfeel lexicon for sparkling wines, 2) train a panel to use this lexicon on white sparkling wines, which represent the majority of sparkling wines, and validate the panel’s performance with white sparkling wines. For lexicon development, 25 sparkling wines were selected from 132 by a team of sensory professionals and winemakers. The lexicon developed included 13 mouthfeel and taste, 48 aroma, and 48 flavor (aromatic) attributes (109 total attributes). For lexicon training, 22 experienced wine panelists participated in 10, 3-hour sessions over two weeks. After training was complete, panel performance was validated with a practice phase and two studies. Analysis of panel discrimination (i.e. sample p-value) and within panel reproducibility (i.e. correlation of panelist with panel intensity) indicated that the new lexicon differentiated sparkling wines consistently. Further, principal components analysis for studies two and three revealed grouping by wine type (e.g. brut, extra dry, etc.) again validating the new lexicon.

Master of Science / Food Science Institute / Fadi Aramouni / The brewing industry has, historically, had little food safety regulation. In response to the September 11th attacks, new legislation culminating in the Food Safety Modernization Act of 2010 was established and reinforced food safety regulations for the brewing industry. Under this expanded regulation, breweries are required to comply with the modernized Current Good Manufacturing Practices (cGMPs). The regulatory climate for the brewing industry is very complicated. The brewing industry is regulated primarily under the jurisdiction of the Alcohol and Tobacco Tax and Trade Bureau and the Food and Drug Administration. Based upon the regulatory environment and business considerations, Boulevard Brewing Company has opted to develop a Hazard Analysis and Critical Control Point (HACCP) plan. Before a HACCP plan can be implemented a foundation of prerequisite programs, based on the FDA’s cGMPs, must be in place. Prerequisite programs establish the operational and environmental conditions required for a successful HACCP plan. Failure to comply with the cGMPs can lead to fines, re‐inspection fees, forced recalls, and possible criminal prosecution. Prerequisite programs were developed for the following areas: facilities, including sanitary design principles, utilities, traffic and product flow; production equipment, including preventive maintenance and calibration; receiving, warehousing, and shipping, including supplier control, chemical control, and raw material testing; pest control for insects, rodents and birds; cleaning and sanitation under a Master Sanitation Schedule; specifications, including ingredients, products, and packaging materials; personal hygiene for both employees and visitors; and lastly a system of traceability and recall. These prerequisite programs, based on cGMPs, are required to ensure regulatory compliance while minimizing regulatory and fiscal risks.

Master of Science / Food Science Institute / Daniel Y.C. Fung / The process of canning or “commercial sterilization” has been studied for more than two centuries. The first to develop canning as a defense against spoilage was Nicholas Appert also known as the “father of canning.” Appert invented a method of preservation by enclosing food in hermetically sealed containers and then heating containers to boiling temperatures for a specific period of time. The canning preservation method has changed over the years, and continues to change for the better. Technology for retorts, or processing vessels, has grown from the traditional steam heating medium to also include water and steam/water spray heating mediums. The once static vessels, now utilize rotation and shaking motions to decrease process time and in turn increase product quality. The product packaging has also evolved to include not only rigid metal containers, but semi-rigid and flexible plastic containers. The variety of packaging adds greater flexibility to the type of food products that can be produced in a shelf stable manner. Canning or “commercial sterilization” is still used today by the food industry as a method of providing safe food with extended shelf life. Today’s goal of commercial sterilization is to continue to produce safe food products that are high in quality and profitable to produce. A variety of processing equipment is available to accomplish those goals, ranging from a basic steam retort to the newest technology on the market known as Shaka. This new retort technology uses reciprocal agitation to shorten processing times and increase the quality of the final products. Studies have shown that the Shaka process reduces processing times better than 20-fold compared to a still process and better than 10-fold compared to a rotary process. As the field of thermal processing continues to evolve, the challenge will be to consistently produce safe, commercially sterile food that exceeds current quality expectations in a shorter process time while using less energy. Shaka, and other new technologies, will help the food industry meet these challenges and expectations by expanding the current capabilities of thermal processing to meet consumer demands.

Master of Agribusiness / Department of Agricultural Economics / Michael Langemeier / This thesis examines flour moisture control and how this control can be an effective tool for cost minimization in a flour mill. Specifically, this thesis discusses the economic rationale behind the value of moisture control, the variables associated with moisture control, options for controlling those variables, the current control strategies, the decision process used to examine moisture control options, analysis of the solution, and implementation of optimal control strategies. In the area of optimal control strategies, two outcomes were generated in the thesis. The first outcome involved collecting data and developing a better understanding of the factors impacting flour moistures. The second outcome was to create a spreadsheet tool for use in the flour mill that would allow operators to determine an optimal water set point that would bring about a desired flour moisture taking into consideration the variables effecting flour moisture and their status at a given time. Both outcomes have been met and are outlined in detail in the thesis. It is understood that the conclusions of this thesis do not represent an end to the flour moisture control challenge and that more research is needed in order to implement further control measures. Work that remains to be done in order to achieve even better moisture control is also outlined in this thesis.

Master of Science / Food Science Institute / J. Scott Smith / Heterocyclic amines (HCAs) are cancer causing compounds formed during the cooking of meat. Previous studies show that incorporating antioxidant spices into meat as well as marinating meat with antioxidant spices reduces formation of HCAs. The purpose of this study was to determine if commercially available spices applied to the surface of meat could effectively reduce HCA formation. Two commercially available spice blends and one blend of spices with known quantities of antioxidant spices were sprinkled onto the surface of beef just prior to pan-frying. The quantities of spices used were based on the amounts customarily consumed in typical Western cooking. The results of direct application were then compared to marinating with the same types and amounts of spices. The antioxidant potential of the spices was analyzed using DPPH and total phenolics methods. Results indicated that the spices would be effective antioxidants. Low recovery rates and problems during the extraction process made results inconclusive, but suggest that further research may find that applying spices directly to the surface of meat in consumer acceptable quantities may be as effective as marinating at reducing the formation of HCAs.

Doctor of Philosophy / Food Science Institute / Kelly J. K. Getty / Salt is used as a preservative in food. Reducing sodium in food, due to its link to hypertension, and replacing NaCl with other types of salt could have an effect on food safety. The main objective was to determine differences in salts and salt substitutes on growth of Listeria monocytogenes in broth and meat and poultry systems. Salts (NaCl, KCl, CaCl2, MgCl2, sea salt, and replacement salt) were added (0.5, 1, and 2.5%) to Listeria monocytogenes (five-strain cocktail) inoculated Listeria enrichment broth at 25 °C and sampled at 0, 24, and 48 h. Results showed that MgCl2, regardless of concentration, caused Listeria monocytogenes populations to grow approximately 0.6 log CFU/mL more (P < 0.05) than the other salts. Fresh ground beef, pork, and turkey with NaCl, KCl, CaCl2, MgCl2, sea salt, and replacement salt (2.0%) were inoculated with Listeria monocytogenes (five-strain cocktail) to determine growth/survival during 5 d at 4 °C to simulate a pre-blend process. Listeria monocytogenes populations significantly decreased (0.41 log CFU/g) during the storage time in beef, however no differences (P > 0.05) were observed over time in pork or turkey. Salt type did not affect (P > 0.05) Listeria monocytogenes populations during pre-blend storage. However, salts (MgCl2 and NaCl) allowed growth (P < 0.05) of aerobic populations during storage. Emulsified beef and pork products were processed with NaCl, KCl, sea salt and a NaCl/KCl blend (2%) and post-processed surface inoculated with Listeria monocytogenes (five-strain cocktail) to determine growth/survival at 4 °C for 28 d. Pork products showed greater (P < 0.05) Listeria monocytogenes population growth at all sampling times (0, 7, 14, 21, and 28 d) than beef products; whereas salt type had no effect on Listeria monocytogenes populations with sampling times pooled for data analysis. Although salt types were not shown to have an impact on Listeria monocytogenes growth/survival in pre-blend and emulsified post-processed surface inoculated meat products, pork and turkey pre-blends and emulsified pork had greater Listeria monocytogenes populations compared to beef products. These studies demonstrate that sodium reduction or replacement may not affect safety of pre-blends and emulsified meat and poultry products.

Master of Science / Food Science / Fadi Aramouni / Due to an increase in awareness of celiac disease, the gluten-free market continues to expand. However, gluten-free breads are still characterized by a poor structure and overall mediocre quality. This research was aimed at determining the impact of egg addition as well as an antistaling agent (DATEM) on the quality of a batter-based gluten-free sorghum bread. Gluten-free bread loaves containing 20, 25, or 30% eggs (as is) on a flour basis were evaluated against a control (no egg). The impact of the antistaling agent, DATEM at 0.5% was also studied for each of these formulations. Quality factors evaluated included water activity, color, specific volume, and cell size. Texture profile analysis was performed to evaluate staling rate based on changes in crumb hardness values and a trained panel evaluated staling attributes by descriptive analysis. Finally, a consumer acceptance test on sorghum bread with and without eggs was also conducted. Results showed that sorghum breads with eggs had higher specific volumes than control (increase from 0.06 cm[superscript]3/g to 0.11 cm[superscript]3/g), while DATEM had a negative effect on the volume of gluten-free bread (decrease of 0.73 cm[superscript]3/g). Eggs also improved cell structure and produced significantly darker crust (p<0.05). Additionally, the addition of eggs reduced bread hardness (from 54 g force to 142 g force on fresh bread) and slowed the rate of staling over the 12 day storage period studied. Descriptive analysis results confirmed the findings of the texture analysis, showing control bread significantly harder (p<0.05) than egg-containing bread at days 0 and 4. The consumer test indicated a significant preference (p<0.05) for sorghum bread with eggs over the control. The overall acceptability score for this bread was above 6 on a 1 to 9 hedonic scale. The score was closer to 7 when the bread was rated by consumers with celiac disease. This research proved that the addition of eggs to a gluten-free sorghum bread formulation resulted in delayed staling and better overall quality and acceptability of the product.