Master of Science / Department of Animal Sciences and Industry / John A. Unruh / The objective of our study was to explore relationships between Japanese color score (JCS) and pork-quality attributes and develop equations to predict JCS. Pork carcass traits in population one (n = 781) was used to develop prediction equations and population two (n = 684) was used to test the equations for accuracy. Pearson's correlation coefficients found firmness, ultimate pH, drip loss percentage, L*, a*, b*, hue angle, and chroma were significantly (P < 0.01) correlated to JCS. Correlation loading found 96% of the variation in firmness, pH, drip loss percentage, L*, a*, b*, and hue angle explained 81% of the variation in JCS. Three prediction equations were developed using these traits. Averages for population one traits were used to develop the initial prediction equations. Predicted JCS, which fell within [plus or minus]0.25 of the actual JCS, were retained and multiple linear regression (MLR) was run, resulting in the first prediction equations. Data from population two were then used to evaluate the success of these equations. Equation one using firmness, pH, drip loss percentage, L*, a*, b*, and hue angle was: JCS = 12.698 – (0.00007199 x drip loss) + (0.09008 x pH) – (0.01128 x firmness) – (0.226 x L*) + (0.06923 x a*) – (0.0201 x b*) + (0.02143 x hue angle); r[superscript]2 = 0.916. For the test population, 98.53 and 67.25% of the observations were predicted within [plus or minus]0.50 and 0.25 of the actual JCS, respectively. The second prediction equation, developed utilizing instrumental color measures of L*, b*, and hue angle was: JCS = 15.255 – (0.259 x L*) – (0.213 x b*) + (0.02518 x hue angle); r[superscript]2 = 0.931. For test population, 92.40 and 55.70% of the observations were predicted within [plus or minus]0.50 and 0.25 of the actual JCS, respectively. The third prediction equation developed utilizing L*, a*, and b* was: JCS = 12.920 – (0.219 x L*) + (0.07342 x a*) – (0.02166 x b*); r[superscript]2 = 0.906. For test population, 97.80 and 68.22% of the observations were predicted within [plus or minus]0.50 and 0.25 of the actual JCS, respectively. All prediction equations predicted 92% or more of the JCS observations within [plus or minus]0.50 and would be useful when sorting pork carcasses for export to valuable Asian markets. The second and third prediction equations would be advantageous as they require fewer measurements and could be more rapidly collected.

Doctor of Philosophy / Department of Grain Science & Industry: Food Science Institute / Sajid Alavi / One of the worst pollution menaces of modern times is plastic packaging, because of its poor degradability. Packaging materials based on starch utilize the benefits of natural polymerization, abundant availability of raw material, and fast biodegradability. However, the highly hydrophilic nature and poor mechanical properties of starch based films limit their application. This problem was sought to be overcome by forming a nanocomposite of starch and layered silicate clay. This study utilizes melt extrusion processing to synthesize starch-clay nanocomposites for biodegradable packaging films and investigate the effects of chemical compatibility of starch, plasticizer and nanoclay and melt extrusion conditions on the structure and properties of composite films. In the first part of the study, the influence of clay type, clay content, starch source and amylose content was investigated. Starch-montmorillonite (MMT) hybrids showed an intercalated nanostructure due to the compatibility of the two components and led to cast film with higher tensile strength and better water vapor barrier properties as compared to starch-organically modified montmorillonite (I30E) hybrids, as well as native starch only. With increase in clay content (0-21 wt%), significantly higher (15-92%) tensile strength (TS) and lower (22-67%) water vapor permeability (WVP) were obtained. The results indicated that nanocomposite technology could be applied to improve the properties of starch-based packaging films. The barrier and mechanical properties of nanocomposite films did not vary significantly with different starch sources (corn, wheat and potato starch), whereas films from regular corn starch showed better properties than either high amylopectin or high amylose-based nanocomposite films. The second part of the study investigated the effects of glycerol content (0-20 wt%) and three plasticizers (glycerol, urea, formamide) on the structure and properties of the starch-clay nanocomposite films. With decreasing glycerol content, the extent of clay exfoliation increased. Films with 5% glycerol exhibited the lowest WVP, and the highest TS and glass transition temperature (Tg). The use of urea and formamide improved the dispersion of clay platelets. Compared to glycerol and urea, formamide has an intermediate hydrogen bond forming ability with starch. However, at the same level of plasticizer (15 wt%), formamide plasticized nanocomposite films exhibited the lowest WVP, highest TS and Tg. Results indicated that a balance of interactions between starch, clay surface modifications and plasticizers might control the formation of nanocomposite structure, and in turn affect the performance of the nanocomposite films. The last part of the study investigated the effects of extrusion conditions (screw configuration, barrel temperature profile, screw speed and barrel moisture content) on the structure and properties of the starch-clay nanocomposite films. Increasing the shear intensity significantly improved the exfoliation and dispersion of clay platelets. The combination of lowest barrel moisture content (20%) and high shear screw configuration exhibited almost complete clay exfoliation and the lowest WVP and highest TS of all treatments. Increasing the barrel temperature also improved clay exfoliation and performance of films. The results suggested that, when polymer and clay are chemically compatible, optimization of process conditions (shear intensity, temperature etc.) can enable significant improvement in clay exfoliation and dispersion and the performance of nanocomposite films.

Norovirus is an enteric pathogen transmitted via the fecal-oral route. It is a leading cause of outbreaks and sporadic cases of gastroenteritis worldwide. Outbreaks of norovirus are often linked to contaminated food or water. Ready-to-eat foods are particularly prone to contamination, since they often require handling during preparation and are not usually heated before serving. Norovirus capsids have been shown to interact specifically with histo-blood group antigens (HBGAs). HBGAs are carbohydrates present on the surface of red blood cells, on mucosal epithelial cells and in bodily fluids. The work in this thesis used the interaction between norovirus and HBGAs to develop a method to detect norovirus in food samples. Magnetic beads were coated with multiple types of HBGA [A, B, H(type 2) and H(type 3)]. These beads were added to a 250 mL volume sample and concentrated using either the Pathatrix(TM) or iCropTheBug. Both systems were able to concentrate the beads from a 250 mL sample to 140 muL, using the magnetic properties of the beads. The RNA was then extracted from the sample and the presence of norovirus was determined using realtime Reverse Transcription-PCR. This method was successful at detecting norovirus from artificially-spiked and naturally-contaminated food samples. It was also able to detect multiple strains from norovirus genogroup I and II within the infectious dose range (10-100 particles). These results demonstrate that carbohydrate-conjugated beads can be successfully used to detect norovirus contamination of food products. This method can provide rapid and effective food testing for use in the investigation of suspected norovirus outbreaks.

No description available.

Master of Science / Department of Grain Science and Industry / Yong Cheng Shi / Isolation of hemicellulose from distillers dry grain with solubles (DDGS) was investigated. Hemicellulose fiber gum (HFG) is a mixture of hemicelluose, protein, ash and starch. It was extracted from a commercial DDGS by heating with or without alkali. Three extraction methods (water heating, alkaline heating and alkaline hydrogen peroxide heating) were evaluated. Yield of HFG and the recovery of hemicellulose were obtained. High heating temperature (100 and 120°C), alkali or hydrogen peroxide facilitated the release of hemicellulose from the cell wall matrix. However combining alkali with 2.5% H2O2 did not extract more hemicellulose out than did alkali alone. The highest hemicellulose recovery was 32% achieved by cooking at 120°C with 2% alkaline solution. Hemicellulose can function as an emulsifier in the oil-in-water emulsions, such as beverage, and potentially replace gum arabic. HFGs obtained by a series of extracting methods were applied in both the concentrated emulsion with the gum: oil: water ratio of 0.5:1: 8.5 and the diluted emulsion with the gum: oil: water ratio of 0.005: 0.01: 1. The emulsion stability was evaluated by turbidity and creaming test. HFG extracted by 2% NaOH solution at 120°C and HFG extracted by 2% NaOH and 2.5% H2O2 solution at 100°C showed the best emulsifying ability among 15 HFG samples. DDGS was produced from corn, sorghum, wheat in the lab. HFGs extracted from sorghum and wheat DDGS were compared with that from corn DDGS. The composition of the three DDGS varied in protein, fat and non-starch carbohydrate contents. Sorghum and wheat DDGS contained higher levels of protein and lower levels of fat and non-starch carbohydrate than corn DDGS. HFG was extracted by 2% NaOH solution at 100°C for one hour and purified by 100% ethanol. The yield of HFG from corn, sorghum and wheat DDGS was 21.08, 11.07, 11.64% respectively, while the hemicellulose recovery was 30.95, 29.74, 22.71% respectively. The water extractable hemicelluloses from all three DDGS had similar ratios of arabinose to xylose.

Master of Science / Department of Grain Science and Industry / Subramanyam Bhadriraju / Heat treatment of food-processing facilities involves using elevated temperatures (46 to 60°C for 24 h) for management of stored-product insects. Heat treatment is a viable alternative to the fumigant methyl bromide, which is phased out in the United States as of 2005 because of its adverse effects on the stratospheric ozone. However, very little is known about responses of the cigarette beetle, Lasioderma serricorne (F.), a pest associated with food-processing facilities, to elevated temperatures. The main objective of my research was to evaluate stage-specific susceptibility of L. serricorne to elevated temperatures to identify the most heat tolerant stage. In the laboratory, I found L. serricorne was able to develop on ground, pelleted feed at 28°C and 65% RH; however, there is no data on the biology of this species on this diet. Therefore, several life history parameters of L. serricorne were studied on ground, pelleted feed at 28°C and 65% RH, to facilitate harvesting stages of specific ages in large numbers for assays with elevated temperatures. The mean duration for eggs was 8.1 d, and the mean egg survivorship was 92.0%. There were four discrete instars, and the mean durations of first, second, third, and fourth instars were 4.7, 4.5, 4.7, 11.8 d, respectively. The survivorship of first through third instars was about 99%, whereas that of fourth instars was 85%. The mean pupal duration was 4.6 d, and pupal survivorship was 98%. Newly eclosed unmated female adults lived 5 d longer than unmated males (29 d), whereas, mated males lived 6 d longer than mated females (17 d). Mated females started laying eggs on the third day after emergence and continued this activity for an additional six to eight days. Females, on average, laid 105 eggs with a mean daily output of 12 eggs. The data reported here provide new information on the biology of L. serricorne on ground, pelleted feed, which appears to be an optimal diet for mass rearing this species. Exposure of eggs, young larvae (3 to 4- July 2007 did not clearly show which of the life stages was heat- tolerant. However, exposure of all life stages to fixed times at 46, 50 and 54°C and 25% RH in the laboratory indicated eggs to be the most heat-tolerant stage. Time-mortality responses, at each of these three d old), old larvae (20 to 21-d old), and adults during heat treatment of a food-processing facility in 20-22 temperatures, showed that the time for 99% mortality (LT99) based on egg hatchability and egg-to-adult emergence was not significantly different at each temperature. The LT99 based on egg hatchability at 46°C was 605 min and it decreased to 190 min at 50°C and 39 min at 54°C. Therefore, during structural heat treatments eggs should be used in bioassays for gauging heat treatment effectiveness, because treatments aimed at controlling the egg stage should control all other life stages of L. serricorne.

Master of Science / Food Science Institute / Karen A. Schmidt / The demand for ultra high temperature processed and aseptically packaged dairy foods is growing throughout the U.S. The technology provides value-added food preservation for many foods including flavored milks, puddings, custards, creams, ice-cream mixes, whey-based drinks, sports drinks, and yogurt. Ultra high temperature nonfat milk, milk, light cream, and 18% cream are used throughout the U.S. by the restaurant and food service industries. There are several advantages to aseptic processing and packaging over traditional pasteurization. Advantages include extended shelf life, lower energy costs, and the elimination of required refrigeration during storage and distribution. Challenges are present in all aspects of dairy processing. Major challenges associated with ultra high temperature processing and aseptic packaging of dairy foods include product quality loss, such as age gelation, fat separation, and flavor loss, as well as manufacturing issues such as limited production capacity, potential contamination, slow packaging speeds, and limited shelf life knowledge. This report reviews the history of aseptic processing, principles of ultra high temperature processing, principles of aseptic filling, quality control of UHT dairy foods, and regulations for dairy processors.

Master of Science / Food Science Institute / J. Scott Smith / In the past 50 years or so dietary fiber has become an increasingly significant area of nutritional focus, debate, and research. Advances in food production practices have resulted in more and more refined foods being available and consumed throughout the world and particularly in developed nations such as the United States. While refined foods are typically more palatable to consumers, the content of dietary fiber is greatly reduced. Currently many diseases are believed to be associated with a lack of dietary fiber intake, and furthermore significant health benefits are thought possible via increased consumption of many dietary fibers. These issues are discussed in Chapter 2- Dietary Fiber and Disease. There is not a well accepted definition for dietary fiber, but most reference the human inability to fully digest fibers, fibers being made up of various monomer units of variable length, and some mention plant origin. In many ways the definition of dietary fiber is connected to the analytical methods used to quantify it, which there are many, several of which are detailed in Chapter 5- Analytical Techniques for Dietary Fiber. Newer ingredients that are not quantified by typical fiber analysis methods have created the need for additional assays. Dietary fiber is subject to all sorts of labeling regulations and a few nutritional claims. This has resulted in many manufacturers taking an interest in increasing the fiber content of their products while maintaining product quality and label friendliness. There are many raw materials/ingredients that can increase the fiber content in foods, each with its own set of functional and sensory characteristics. These are detailed in Chapter 7 and include acacia gum, beta glucan, cellulose, chitin/chitosan, corn bran, corn fiber, inulin, oat Bran/oat fiber, pea fiber, pectin, polydextrose, psyllium, resistant starch, rice bran, soy fibers, wheat bran, and wheat fiber. These fibers are unique in their functional capability and effect on flavor and texture. Discussion of the product development considerations includes these functional characteristics as well as cost, ingredient labeling requirements, usage levels, other sensory characteristics, storage stability, and effect on water activity.

Master of Science / Food Science Institute-Animal Science & Industry / Daniel Y.C. Fung / Three experiments were conducted to study the antimicrobial effectiveness of persimmon puree and phenolic compounds commonly found in the persimmon and plum. The objectives in experiment 1 were to evaluate the antimicrobial effects of persimmon puree on BioballTM Listeria monocytogenes and Escherichia coli O157 in a liquid medium. Persimmon puree was added at 1, 3, 5, and 10% wt./vol concentrations to brain heart infusion broth and inoculated with BioballTM Listeria monoctogenes and BioballTM Escherichia coli 0157. Microbial growth was evaluated at 0, 24, 36 and 72 h. Results indicated that at 24 h, persimmon puree at all concentrations suppressed (P<0.05) growth of L. monocytogenes compared to the control. Suppressed (P<0.05) growth of L. monocytogenes continued through 36 and 72 h for all concentrations of persimmon puree tested. However, due to non-pathogenic background Gram-negative micoflora, inhibition of E. coli O157 could not be ascertained. The objectives of experiment 2 were to evaluate the antimicrobial effectiveness of selected phenolic compounds (benzoic acid, gallic acid, vanillic acid, chlorogenic acid, and quercetin on E. coli O157:H7, Salmonella Typhimurium, Bacillus cereus, Yersinia enterocolitica, L. monocytogenes, and Staphylococcus aureus. Quercetin, vanillic, and chlorogenic acids were effective against selected pathogens at varying levels, but not as potent as Benzoic or Gallic acid. Results indicated that benzoic acid had the most effect against E. coli O157:H7, S. Typhimurium and B. cereus at concentrations of 452.98, 239.63 and 518.79 µg/ml, respectively. Gallic acid was the most effective against Y. enterocolitica, L. monocytogenes, and S. aureus at concentrations of 11.01, 29.06 and 22.45 µg/ml, respectively. The objective of experiment 3 were to evaluate the antimicrobial effectiveness of persimmon puree at concentrations of 0, 3, 5 and 10% wt./wt on a five strain cocktail of L. monocytogenes in ground beef. There was no suppression of growth at any concentration at 0, 1, 3 or 5 d. However, there was an increase (P<0.05) on 5 d for concentrations 5 and 10% persimmon puree when compared to the control. These series of experiments suggest that benzoic and gallic acids may have potential to suppress microbial growth. Persimmon puree appears to be an effective antimicrobial agent against Gram-positive bacteria in a liquid medium. However, incorporation of persimmon puree into ground beef did not yield an antimicrobial effect. Therefore, more research needs to be conducted to validate the effectiveness of phenolic compounds and persimmon puree as antimicrobial agents in food substances.

Master of Science / Food Science Institute - Grain Science & Industry / Thomas J. Herald / Donghai Wang / The number of people diagnosed with celiac disease has increased and subsequently the market for gluten-free products is rising. Sorghum has been identified to be a safe grain to use as a wheat alternative for the celiac community. There are many sorghum hybrids that are commercial available for use in food and feed. Noodles are selected for the growing market in the US and the lack of research and availability for sorghum noodles. Viscoelastic properties are crucial for making acceptable noodles which makes this research more challengeable. The research hypothesis is that sorghum can be used in making gluten-free noodles and there are end product quality differences that exist among the hybrids in production of gluten-free noodles. A series of chemical and physical analyses were conducted to compare four sorghum hybrids (Orbit, NE #8, F-525, NE #4) in a gluten-free noodle system. The noodles were formulated with 100% sorghum flour and the other functional ingredients including dried whole eggs, egg whites, xanthan gum and corn starch. Sorghum noodles were significantly different in color, texture and cooking quality among hybrids. The starch properties were found to have more effect than protein content on sorghum noodle qualities. Sorghum flour with fine particle size and low ash content was crucial for making acceptable sorghum noodles. Noodles made from sorghum F-525 exhibited some properties significantly closer to the commercial wheat flour noodles.