Master of Science / Food Science Institute / Randall K. Phebus / With the implementation of the Food and Drug Administration’s Food Safety Modernization Act, the food industry must scientifically verify that current production processes provide sufficient protection against pathogens. This study was conducted to validate a simulated commercial baking process for hamburger buns to control Salmonella spp. contamination and to determine the appropriateness of using non-pathogenic surrogates (Enterococcus faecium ATCC 8459 or Saccharomyces cerevisiae) for in-plant process validation studies. Wheat flour was separately inoculated (~6 log CFU/g) with three Salmonella serovars (Typhimurium, Newport or Senftenberg) or E. faecium. Dough was formed, proofed, and baked to mimic commercial manufacturing conditions. Non-inoculated dough was used to evaluate S. cerevisiae (Baker’s yeast) survival during baking. Buns were baked for 9, 11 and 13 min in a conventional oven set at 218°C, with internal bun temperature profiles recorded. Salmonella serovars and S. cerevisiae were reduced by >6 log[subscript]10 CFU/g after 9 min of baking. E. faecium was detected by direct plating after 11 min of baking but not after 13 min. After 13 min of baking, all three target organisms were eliminated (>6 log CFU/g reduction) in the buns. D- and z-values of Salmonella spp. (3-serovar cocktail), E. faecium, and S. cerevisiae in bun dough were also determined. D-values of Salmonella spp. and E. faecium during heating of dough were 28.64 and 133.33, 7.61 and 55.67, and 3.14 and 14.72 min at 55, 58 and 61°C, respectivly; whereas, D-values of S. cerevisiae were 18.73, 5.67 and 1.03 min at 52, 55 and 58°C, respectivly. The z-values of Salmonella spp., E. faecium and S. cerevisiae were 6.58, 6.25 and 4.74ºC, respectively. E. faecium demonstrated greater thermal resistance than Salmonella spp. and S. cerevisiae, making it an appropriate (and conservative) surrogate to establish thermal process lethality in the validation of commercial baking operations. The low thermal tolerance of S. cerevisiae relative to Salmonella limits its usefulness as a potential surrogate for process validations.

Master of Science / Food Science Institute / Elizabeth A. Boyle / Pork preblends held for 0, 4 or 7 d were formulated into smoked sausages and analyzed for cook yield, instrumental external color, pH, salt content, proximate analysis, Warner-Bratzler shear force (WBSF), thiobarbituric acid reactive substances (TBARS), sensory analysis and purge percentage during 0, 110, 131 and 160 d display at an average 2.65 °C under fluorescent lighting. One preblend × day of display interaction was found for b* values. On display d 0, preblend d 7 was more yellow (P < 0.05) than preblend d 0 and 4; however, no differences (P > 0.05) were found for any preblends on d 110 or 160. On display d 131, preblend d 0 was more (P < 0.05) yellow than preblend d 4 but similar (P > 0.05) to preblend d 7. There was no preblend effect (P > 0.05) on any of the other attributes measured. Display day did not affect (P > 0.05) purge, pH, proximate analysis, WBSF, juiciness, saltiness or off-flavor. For color, a* and saturation index values decreased (P < 0.05) and L* increased (P < 0.05) between d 0 and 110 as well as d 110 and 131, while L*, a*, a*/b* ratio and saturation index values were similar (P > 0.05) from d 131 to 160. Hue angle value decreased from d 0 to 110 but was similar for the remaining display. A reduction (P < 0.05) in a*/b* ratio was shown from d 0 and 110 (average 0.85) to d 131 and 160 (average 0.78). There was a reduction in salt content by 0.43% and an increase in TBARS values by 0.46 mg malonaldehyde/100 g sample from d 0 compared to d 110, 131 and 160 (P < 0.05). Inconsistent differences were found for sensory panel traits bite and flavor intensity and a reduction in mouthfeel coating was found from d 0, 110 and 131 compared to 160 (P < 0.05). Therefore, preblending could be implemented without any detrimental outcome on quality or sensory attributes of skinless smoked sausage; however, as day of display increases product may become lighter, less red and more oxidized.

Master of Science / Department of Grain Science and Industry / Greg Aldrich / Pet food is a $23 billion industry that continues to grow. Owners continue to humanize their pets and their dietary needs, thus the pet food industry tends to mirror human dietary trends. Currently, pet food is trending towards higher levels of protein, thus lower levels of starch. Decreasing starch, one of the main structure forming ingredients in extruded foods, creates issues in terms of lower rates of expansion and decreased kibble durability. Consumers tend to dislike ingredients that do not serve a dual nutritional purpose; therefore gelatin may be a plausible binding ingredient for high protein pet foods. Gelatin is a pure protein derived from collagen and is sold as a dry, odorless, tasteless powder. High-bloom gelatins find numerous uses in the human food as a stabilizer, foaming agent, and capsule base among other uses. Low-bloom gelatin may find a value-adding opportunity as a nutritional binder in the pet food market. Four extrusion experiments were performed to test this hypothesis. Experiment 1 compared gelatin at 0%, 5%, 10%, and 15% inclusion and 15% gelatin at 3 different extruder screw speeds. Results showed a decrease in expansion but an increase in hardness and pellet durability index (PDI); however there may have been inadequate preconditioning. It was unclear whether the decrease in expansion or presence of gelatin improved product durability. Experiment 2 analyzed two levels of gelatin, 0% and 10%, under two extruder screw speeds, 300 rpm and 500 rpm, and two hydration ratios, 17% and 28%. In this experiment, there were no differences in density, expansion, hardness, or PDI. This indicated that preconditioning was more ideal and may indicate gelatin does not decrease product expansion. Experiment 3 analyzed two levels of gelatin, 0% and 10%, at two target densities, low and high. Results indicated that gelatin created a more expanded product when processed under similar conditions as a control formula. Experiment 4 analyzed different strengths of gelatin to determine if the low-bloom gelatin experiments were repeatable with more conventional strength gelatins. Treatments were a control with no gelatin, and a 100 bloom, 175 bloom, and 250 bloom gelatin. Results showed increased gelatin strength increased product expansion, likely through a foaming effect. However, durability declined with mid- and high-bloom gelatins; thus, low-bloom gelatin may be the most promising to improve product characteristics and preserve durability. Two additional experiments were performed in order to explore gelatin bloom strength in injection molded treat processing. A lab-scale experiment was performed to optimize an initial formula. Tensile strength, strain at break, Young’s Modulus, puncture force, and peaks were measured. It was determined that equal parts gelatin, gluten, and glycerin were most ideal for further testing purposes. Determination of gelatin bloom strength effects with three bloom strength gelatins were used to produce beadlets on a pilot-scale twin-screw extruded and production model injection molding system. Differences were noted between treatments; wherein high bloom gelatin created a softer, more stretchy treat and low bloom gelatin created a tougher, more rubbery treat. Low-bloom gelatin may find use as a nutritional binder in high protein pet foods and may be an alternative to high-bloom gelatin in injection molded dental treats.

Master of Agribusiness / Department of Agricultural Economics / Vincent R. Amanor-Boadu / The intent of this thesis is to conduct a case study on the optimization of blending soft red winter wheat, prior to processing into flour, in order to meet specific solvent retention capacity, SRC, specifications, based on predetermined customer specifications. The thesis will provide the company with a greater understanding of how to effectively manage the customer’s demands, and the costs associated with these activities in order to create greater customer value. If optimizing wheat blends is successful, the company will be able to provide similar SRC information to other customers as a value added service. (Solvent retention capacity) is a test that provides analytical data that measures three specific physical components within soft wheat flour. Traditionally, wheat flour is sold according to moisture, ash, protein content, and basic dough characteristic data; though this information is important, SRC provides specific flour functionality information that will aid customers. SRC examines the: glutenin characteristics of the flour, pentosan content and gliadin characteristics, and the starch damage from the milling process. These values describe the functionality of the flour and provide information regarding the flour’s ability to absorb water during the mixing process and the flour’s ability to release that water during the baking process. SRC quality endpoints include: reduced mixing and baking times, reduced levels of breakage after baking, and greater overall ingredient consistency throughout all the customer’s commercial bakeries. This thesis develops a process that the company may use to meet SRC quality specifications determined by the customer. The company gains customer loyalty by supply a consistent product to the customer. This product in turn yields savings for the customer in the areas of lower water use, shorter baking time and consequently lower energy use.

Doctor of Philosophy / Department of Grain Science and Industry / Praveen V. Vadlani / The purpose of this study was to investigate micro- and macro-scale aspects of solid state fermentation (SSF) for production of cellulolytic enzymes using fungal cultures. Included in the objectives were investigation of effect of physicochemical characteristics of substrate on enzymes production at micro-scale, and design, fabrication and analysis of solid-state bioreactor at macro-scale. In the initial studies response surface optimization of SSF of soybeans hulls using mixed culture of Trichoderma reesei and Aspergillus oryzae was carried out to standardize the process. Optimum temperature, moisture and pH of 30ºC, 70% and 5 were determined following optimization. Using optimized parameters laboratory scale-up in static tray fermenter was performed that resulted in production of complete and balanced cellulolytic enzyme system. The balanced enzyme system had required 1:1 ratio of filter paper and beta-glucosidase units. This complete and balanced enzyme system was shown to be effective in the hydrolysis of wheat straw to sugars. Mild pretreatments– steam, acid and alkali were performed to vary physicochemical characteristics of soybean hulls – bed porosity, crystallinity and volumetric specific surface. Mild nature of pretreatments minimized the compositional changes of substrate. It was explicitly shown that more porous and crystalline steam pretreated soybean hulls significantly improved cellulolytic enzymes production in T. reesei culture, with no effect on xylanase. In A. oryzae and mixed culture this improvement, though, was not seen. Further studies using standard crystalline substrates and substrates with varying bed porosity confirmed that effect of physicochemical characteristics was selective with respect to fungal species and cellulolytic activity. A novel deep bed bioreactor was designed and fabricated to address scale-up issues. Bioreactor’s unique design of outer wire mesh frame with internal air distribution and a near saturation environment within cabinet resulted in enhanced heat transfer with minimum moisture loss. Enzyme production was faster and leveled within 48 h of operation compared to 96 h required in static tray. A two phase heat and mass transfer model was written that accurately predicted the experimental temperature profile. Simulations also showed that bioreactor operation was more sensitive to changes in cabinet temperature and mass flow rate of distributor air than air temperature.

Master of Agribusiness / Department of Agricultural Economics / Jason Bergtold / Company managers continually face challenges in the market, such as increased demand for their services and variability in the types of service requested. In addition, managers may face internal challenges during periods adjustment such as moving the company forward through a hiring freeze. In these situations, a manager must be able to allocate their scarce resources in a way to continue to perform. For employees, this could mean specializing in tasks or increasing crosstraining to improve work schedule flexibility. The objective of this research is to determine the optimal allocation of employees to tasks, given resource constraints and the need for staff flexibility, to satisfy alternative management strategies. The setting is the service industry, in particular a laboratory setting providing testing and consulting services. An optimization model was developed to incorporate key aspects of a company’s operation, and determine labor allocation among tasks, and for how many hours, to satisfy the manager’s objective. The model estimates the optimal allocation of labor and how much production and net revenues would be generated, with more specialized employees. A sensitivity analysis was employed to determine the impact of cross-training current staff. Results indicate that cross-training affords flexibility; however, the impact on overall production varies depending on the employee trained. The highest benefit is derived from training a lower-producing employee into a high value task at a high productivity rate. Specialization can help to improve productivity in net returns for higher valued tasks, but may limit flexibility, as employees cannot switch between tasks as readily.

Doctor of Philosophy / Department of Food Science / Daniel Y.C. Fung / In the food industry, coliform testing is traditionally done by the time consuming and labor intensive plate count method or tube enumeration methods. The TEMPO® system (bioMérieux, Inc.) was developed to improve laboratory efficiency and to replace traditional methods. It uses a miniaturization of the Most Probable Number (MPN) method with 16 tubes with 3 dilutions in one single disposable card. It utilizes two stations: the TEMPO® Preparation station and the TEMPO® Reading station. In this study, the Oxyase® (Oxyase®, Inc.) enzyme was added to TEMPO® CC (Coliforms Count), TEMPO® AC (aerobic colony count) and TEMPO® EC (E. coli Count) methods. Water samples of 1 ml with 0.1 ml of Oxyase® enzyme were compared to samples without the Oxyase® enzyme using the TEMPO® system. Samples were spiked with different levels of coliforms (10, 102, 103 and 104 CFU/ml), stomached (20 sec), and pipetted into the three different TEMPO® media reagents (4 ml) in duplicate and then automatically transferred into the corresponding TEMPO® cards by the TEMPO® preparation station. Counts were obtained using the TEMPO® reading station after 8, 12, 16, 22 and 24 hours at an incubation temperature of 35°C. Results from 20 replicates were compared statistically. Using TEMPO® tests, high counts in food samples (>6 log 10 CFU/ml) can be read in 6±2 hours of incubation using the time-to-detection calibration curve. The TEMPO® system reduces reading time (reading protocol should be changed). There is no need to wait for 22 hours of incubation only 12 hours is required. Oxyrase® enzyme is not needed for the TEMPO® system.

Master of Science / Food Science / Kelly J.K. Getty / James L. Marsden / Escherichia coli O157:H7 outbreaks have been linked to leafy green produce and bagged spinach. The objective of this study was to evaluate a Photohydroionization (PHI) panel (novel advanced oxidation technology) and varying concentrations of lactic acid washes for controlling E. coli O157:H7 on baby spinach. Leaves were dip inoculated with a five-strain cocktail of E. coli O157:H7 inoculum having a concentration between 5-6 log CFU/ml. Leaves were submerged in inoculum for 30 s and dried for 1 h. Non-inoculated and inoculated leaves were washed for 30 s in food grade lactic acid diluted to concentrations of 0.5, 1.0, or 2.0% and allowed to dry for 10 min. For PHI treatment, leaves were placed under the PHI panel and treated for 1, 2, or 5 min on both sides for total treatment times of 2, 4 or 10 min. Following treatments, leaves were either sealed in low-density polyethylene bags or enumerated. Samples were enumerated at 0, 3, 7, 10, and 14 days following inoculation. Ten gram samples were diluted with sterile peptone and stomached for one min, and then 0.1 ml was plated onto sorbitol MacConkey agar with cefixime and tellurite plates that were incubated at 37°C for 24 h. For lactic acid treatments, E. coli O157:H7 populations were different (P < 0.05) compared to the control. There was no difference (P > 0.05) due to sampling time so sampling times where pooled together for each lactic acid concentration of 0.5, 1.0, and 2.0% and resulted in 2.01, 2.78, and 3.67 log CFU/g reductions, respectively. Leaves treated with 1.0% and 2.0% lactic acid had color degradation and were organoleptically unacceptable by day 14. When leaves were treated with PHI for 1, 2, or 5 min per side, E. coli O157:H7 populations were reduced 1.6, 1.49, or 1.95 log CFU/g, respectively. Leaves treated with PHI were not different from one another, but were different (P < 0.05) from the positive control. No color change occurred in leaves treated with PHI. The PHI panel and lactic acid washes of 0.5% or higher are effective in reducing E. coli O157:H7 in baby spinach.

Master of Agribusiness / Department of Agricultural Economics / Bryan Schurle / The milling of wheat into white flour is a high volume, low margin business. Flour is a commodity. Competition is fierce. Over the past several years, there have been several mergers and acquisitions leading to fewer, but larger flour mills. The number of companies in the flour milling business has diminished as well. Flour sold in small packages on the grocery store shelf is but a small part of the business these days. Most flour is sold to commercial bakers in large bags or bulk trucks. The process of milling wheat into white flour consists of numerous variables within an extensive collection of equipment. It is the job of the miller to minimize the negative impact of these variables or at least hold constant as many of these variables as possible while achieving the best efficiency possible. To lessen the effect of these numerous variables on a large extensive system makes for a well running operation. When efficiency is achieved, a flour milling operation can be a profitable venture. A number of the variables that influence efficiency are affected by the amount of flour storage that a flour mill has. This thesis examines the benefits of flour storage as related to flour process efficiencies in milling. With flour mills operating at large output capacities, it is necessary for a flour mill to have adequate bulk flour storage bins as well as the right amount of warehouse space. Changes from one type flour to another in a flour mill require some time and an abundance of intervention by a skilled operator or miller. Having the proper amount of storage space makes it possible to minimize changes as well as the opportunity to optimize production of each specific flour type that is processed on the mill. To justify capital project money to invest in the proper amount of storage can be a challenge. Warehouse space and bulk flour storage can be expensive, and it is difficult to quantify how theoretical improvements will increase production and quality in the end product of flour. Using regression methods, production data obtained from an average sized commercial flour mill was used to estimate the increase in extraction due to a longer length of run allowed by the addition of storage space. By increasing the time a mill stays on a specific wheat mix to a minimum of twenty hours, there is a theoretical increase in extraction of 1.02 percentage points, resulting in wheat savings of over $500,000 per year. This resulting savings on the raw input material showed that capital expenditures on storage can be justified. A positive net present value and good internal rate of return show that the increased efficiency due to longer lengths of run justified the additional expense of the additional storage capacity. As volatility and the price per bushel of grain continue to increase, having the proper plant infrastructure with regard to storage space is of the utmost importance. Other benefits of storage will be realized as well in the area of flour quality and customer service.

Master of Science / Department of Grain Science and Industry / Sajid Alavi / Extrusion processing and frying are the two most commonly used methods to produce savory snacks. These snacks are mostly starch based and also contain high amounts of fat. Snacking percentage has increased drastically over the past few decades causing many health problems like obesity, hypertension and cardiovascular diseases. The overall objective of this study was to develop novel soy based savory snack that are high in protein and has less fat using both extrusion processing and frying. In the first part of this study both defatted soy (25-75%), wheat flour, monoglycerides (0.375 & 0.75%) and sodium bicarbonate (0 and 0.5%) were used to produce dense extrudates, which mimic the shape of lentils using pilot scale twin screw extruder. The extrudates were soaked in water and fried in corn oil to produced savory snacks. Soy influenced the water absorption during soaking and oil uptake during frying. The water uptake and % fat decreased with increase in soy and the amount of water uptake influenced the % fat absorption in the product. No significant differences were observed in overall acceptability and to summarize the increased protein and dense structure of the products challenge the texture of the products. In the second part of this research, dynamics of water and oil uptake were studied to see the role of texture modifiers like soy protein isolate (4, 8, & 12%), calcium bicarbonate (0.2, 0.4 & 0.6%) and pregelatinized wheat starch (4, 8, & 12%) on texture, water and oil uptake. Descriptive sensory analysis was conducted to study the sensory attributes of the products. Water holding capacity is influenced by the level of % starch addition and the degree of starch degradation during processing. Oil uptakes correlates to that of WHC and is also affected by the degree of gelatinization and crust formation. Degree of starch gelatinization, oil uptake and oil and starch matrix interactions had an impact on hardness. Among SPI, CaCO3 and PGWS, PGWS lowered the product hardness followed by SPI and CaCO3. Descriptive sensory results are similar to experimental results with PGWS samples having lower initial or substantial hardness and more oxidized or heated oil aroma and flavor.