Master of Science / Department of Grain Science and Industry / Yong Cheng Shi / Maltogenic amylases are widely being used as an antistaling agent in baking industry. However, their action on starch in granular, swelled and dispersed forms, important components formed during bread baking, is largely unknown. Actions of two maltogenic amylases- A and -B on waxy maize starch (WMS) (100% amylopectin) and normal wheat starch (NWS) (~25% amylose) were studied and compared. For any given starch type, starch form, and hydrolysis time, maltogenic amylase-B hydrolyzed both starches more than maltogenic amylase-A as seen through sugar profile analysis indicating its higher degree of multiple attack action (DMA). Their action on non reducing ends blocked compound, p nitrophenol maltoheptaoside, confirmed their endo action. Maltogenic amylase-B showed a higher endo to total enzyme activity ratio than maltogenic amylase-A at any given enzyme weight. Greater MW reduction of dispersed starches by maltogenic amylase-B indicates its higher level of inner chain attack (LICA). Interestingly, MW distributions profiles of swelled starch hydrolysates did not show significant differences irrespective of swelling temperatures. Both enzymes showed differences in oligosaccharides compositions in dispersed and swelled starches’ reaction mixtures with sugars of degree of polymerization (DP) > 2 being degraded to glucose and maltose during later stages. For granular starches, enzymes followed a random pattern of formation and degradation of sugars with DP >2. MW distributions of hydrolyzed granular starches did not show significant shift until at the end of 24h when a low MW peak was observed. Morphological study of granular starches showed that maltogenic amylase-A mainly caused pinholes on WMS while maltogenic amylase-B caused surface corrosion with fewer pinholes. For NWS, both enzymes degraded A granules with deep cavities formation during later stages. A decrease in crystallinity of granular starches means that enzymes were able to hydrolyze both amorphous and crystalline regions. These results indicate that maltogenic amylase-B with a high LICA and high DMA possesses a better starch binding domain which can decrease the starch MW without affecting bread resilience. Strucuture of maltogenic amylase-A modified amylopectin (AP) in relation to its retrogradation was also studied. AP retrogradation was completely inhibited at % DH ≥ 20. MW and chain length distributions of debranched residual AP indicated with increase in % DH, a high proportion of unit chains with DP ≤ 9 and low proportion of unit chains with DP ≥ 17 were formed. Higher proportion of short outer AP chains which cannot participate in double helices formation supports the decrease and eventually complete inhibition of retrogradation. Thus, maltogenic amylase-A can play a very powerful role in inhibiting starch retrogradation even at limited DH (%).

Master of Science / Department of Food Science / Kadri Koppel / Pomegranate fruits are seasonally produced and require processing to provide year round availability. Effects of processing on phenolic compounds, color, and other physical properties have been examined but few studies have examined the sensory effects. Juice prepared from fresh Wonderful pomegranates was used to prepare fresh frozen juice, batch pasteurized juice, and reconstituted juice from dried arils. These juices were evaluated using analytical and affective sensory methods to increase the understanding of processing effects on pomegranate juice properties. A modified consensus flavor profile showed that a large number of small differences existed. The accumulation of these changes demonstrates the distinction among processing methods. Time intensity multi-evaluation (TIME) profiling, a new method, was used to further understand how multiple attributes, including aromatics, feeling factors, and basic tastes, changed over the course of one sip. Fruity flavor was consistently the first to appear in the profile while bitterness and astringency lasted the longest. The attribute woody displayed longer peak times in the pasteurized and reconstituted samples than seen in fresh frozen juice. Semi-Continuous Consumption (SCC) profiling, another new method, explained product differences over 25 sips that mimicked consumption. Overall, astringent and bitter components increased while fruity and overall sweet attributes declined. These profile changes differed by sample with reconstituted juice showing the least increase in astringency over consumption. The juice samples were subjected to an acceptance test that showed four liking clusters, one that accepted all three juices and three clusters that disliked one of each juice type. The results from these studies are an initial step in describing how processing of pomegranate juice can effect flavor. Understanding the flavor differences is beneficial to processors for marketing products and for purchasers of these products for ingredient usage. Furthermore, the process of TIME and SCC profiling are described which are beneficial for understanding how multiple flavors change over single and multiple consumption events of a product respectively. These new methodologies are useful in explaining the experience of complex products such as teas and coffees or products exhibiting build-up such as nutrition aides.

Doctor of Philosophy / Department of Grain Science and Industry / Hulya Dogan / The concept of thermal processing of foodstuffs has been used extensively since 1920 when the first scientific basis for calculating the minimum safe sterilization process was developed. There are several methods used in thermal processing of dry foods including infrared, microwave, hydrothermal treatments such as annealing and heat-moisture treatment, thermomechanical treatments (extrusion), and indirect (hot air) and indirect (steam) heating. Thermal processing has been the most widely used method for preserving and extending the shelf-life (via microbial reduction and enzyme inactivation, and for improving quality and functionality. In 2009 the Centers for Disease Control and Prevention released a report of an Escherichia coli outbreak resulting from consumers eating raw refrigerated cookie dough which brought attention to heat treatment of flours and powders. Chlorination of wheat flour in the European Union countries has been replaced in recent years by heat-treated flour which is used to produce high ratio cakes. By applying heat treatment, it is possible to modify the physical and rheological properties. The primary effect of heat treatment is denaturation of the proteins, partial reduction or inactivation of alpha-amylase, and partial gelatinization of the starch. Understanding of relationship between heat transfer, thermal properties of food, heating medium, thermodynamics and the functionality of the resulting heat-treated flour is of critical importance. Research reported in this dissertation has five chapters. Chapter 1 provides a general overview on the state-of-knowledge in the area. Chapter 2 focuses on developing a thermomechanical treatment (extrusion) for improving the functionality of low quality (ash > 1.3%) wheat flour. Chapter 3 deals with developing a direct, rapid and continuous thermal processing technique for treating whole wheat flour and whole wheat grain, and investigates physicochemical changes of heat-treated samples at various moisture-time-temperature combinations. Chapter 4 explores the mixing and development of composite flours in the presence of gluten fractions of at varying proportions, mixing speed and temperatures. Chapter 5 highlights general conclusions and identifies areas for future research.

Master of Science / Department of Animal Sciences and Industry Food Science / Elizabeth Boyle / Unpasteurized fruit juices have been implicated as the source of foodborne outbreaks due to pathogens such as Salmonella, Escherichia coli O157: H7 and Cryptosporidium parvum. The growth of pathogens can usually be slowed through freezing or largely eliminated through pasteurization. Although pasteurization is often effective in eliminating pathogens, it often yields undesirable flavors that are unlike those of fresh juice. Growing consumer trends towards “healthy” unpasteurized alternatives are fueling the development of alternative processing techniques. Several promising techniques for pathogen reduction in the processing of fruit juices are currently being developed. A new technique that is already being marketed worldwide is hyperbaric processing (HPP) which subjects the fruit juice to a high pressure of up to 1000 MPa. The high-pressure treatment results in up to a 7 log reduction kill in pathogens while preserving the naturally occurring flavor profile, sensory attributes and nutritional benefits. Pulsed electric fields (PEF) and ionizing radiation are also being widely explored as viable techniques to process unpasteurized fruit juices. PEF promises to be a commercially viable energy efficient alternative to pasteurization, adding only $0.03 – $0.05 per liter to final food costs. Although irradiation enjoys support for use in the processing of fruit juice by regulatory agencies, support in public opinion is lacking and hinders its growth as an alternative to pasteurization. Other experimental techniques are also present in the development pipeline. Ultrasonic radiation and high intensity pulsed light radiation are both experimental techniques that are being researched. A particularly exciting alternative is the use of plant-based antimicrobials. Several fruits and spices are known to be natural antimicrobials and are therefore being researched as alternatives to the traditional chemical preservatives.

Master of Science / Department of Grain Science and Industry / Kingsly Ambrose / It is a well-known phenomenon that the break-release, particle size and size distribution of wheat milling are functions of machine operational parameters and grain properties. Due to the non-uniformity in characteristics and properties of wheat kernel, the kernel physical and mechanical properties may affect the size reduction process. The discrete element method (DEM) is a numerical modeling technique that can be used to study and understand the effect of physical and mechanical properties of a material on processing. The overall objective of this study is to develop a DEM model of the 1st break wheat milling process. In this study, different physical and mechanical properties of wheat mill streams were determined for using as the input parameters in DEM model development. The particle size and size distribution (PSD), true, bulk and tapped density, young’s modulus, coefficient of static and rolling friction, and coefficient of restitution were measured for wheat kernel, 1st break and flour from hard red winter (HRW), hard red spring (HRS), and soft red winter (SRW) wheat. Overall moisture content was found to have a greater significant effect on the physical properties i.e. density and PSD of the mill streams than material properties i.e. Young’s modulus, coefficients of friction and coefficient of restitution. The DEM model of 1st break wheat milling was developed using both single and multi-sphere approaches. The single sphere approach simulated the size reduction of a spherical cluster of bonded particles with mono-sized particles. The model was simulated for hard red winter (HRW) wheat milling at 16% moisture levels and validated using lab scale milling trials giving a PSD of 437.73 m with a percent deviation of prediction of 235.37. The deviation of prediction was reduced to 192.29 with a mean PSD of 371.52 m by conducting sensitivity analysis by modifying the shear modulus and coefficient of restitution values. In the multi-sphere approach, a bonded cluster resembling a wheat kernel in shape and size was used to simulate the milling process. The model predicted a 1st break PSD of 412.65 µm which had a deviation of 185.89 from lab scale and 156.78 from plant scale milling. The model could however satisfactorily predict the variation in PSD from 1st break milling with moisture content with reasonable accuracy. Future capabilities using the model include performing additional sensitivity analysis to understand the effect of other mechanical properties of wheat on the 1st break PSD. It can also be used to improve the 1st break release during wheat milling.

Master of Science / Food Science Institute / Delores Chambers / Psychographic Questionnaires: A Comparative Review of Structures and Scales In recent years there has been a growing trend toward integrating psychographic profiles into sensory studies with the aim of more holistically explaining consumer segmentation and preferences. With this shift in approach have come questions on the nature of psychographic scales and the theoretical implications of their structure. Given the plethora of existing psychographic scales in common practice, the purpose of this review is to give a concise overview in the breadth of structures, with the aim of helping sensory researchers identify the most appropriate scale for their needs. The review begins with a critical comparison of the three most common scale classes: Likert, Semantic Differential, and Behavioral Frequency, and their relative advantages and disadvantages. Following that, a review of psychographic questionnaire design highlights differences from sensory practices, drawing attention to sources of response bias in specific design typologies which may reduce data quality in a product design.

Doctor of Philosophy / Food Science Institute / J. Scott Smith / The International Agency for Research on Cancer (IARC) has classified 4(5)-methylimidazole (4-MeI) as a possible human carcinogen. Also, the National Toxicology Program (NTP) has concluded that 4-MeI is a probable cancer causing agent. Even though 4-MeI has been detected in several processed foods no research has been conducted to measure levels of 4-MeI in processed meat. A method using isobutylchloroformate (IBCF) and gas chromatography mass-spectrometry (GC-MS) was developed to detect and quantify 4-MeI in processed meat products. Levels of 4-MeI ranged from 0.04 to 1.01 μg/g with recovery of 94.76 to 103.94%. Formation of 4-MeI in glucose-amino acid model system was studied. [subscript]D-Glucose (Glu) was mixed individually in equimolar concentrations of 0.05, 0.1, or 0.15 M and equal volume with [subscript]L-Alanine (Ala), [subscript]L-Arginine (Arg), Glycine (Gly), [subscript]L-Lysine (Lys), and [subscript]L-Serine (Ser); and the mixtures were heat treated at 60, 120, and 160°C for 1 h. Among all tested amino acids, Glu-Arg produced the highest level of 4-MeI. The Glu-Lys model system showed higher browning and lower concentrations of 4-MeI. The effect of ascorbic acid (ASA), a strong antioxidant, was studied in the Glu-Arg model system. Four concentrations of ASA (0.0375, 0.075, 0.15, and 0.3 M) were mixed with 0.15 M equimolar of Glu-Arg and heat treated at 160°C for 1h. ASA inhibited formation of 4-MeI by 40.29, 69.94, 75.13, and 96.25% for the 0.0375, 0.075, 0.15, and 0.3 M concentrations. Contrarily, ascorbic acids increased the browning in all treatments compared to control treatment by 10.67, 15.47, 18.4, and 28.8% for the 0.0375, 0.075, 0.15, and 0.3 M concentrations. Adding ASA to processed food may reduce formation of 4-MeI and increase the browning that is a desired attribute to processed meat products.

Master of Science / Food Science - Human Nutrition / Delores Chambers / Researchers evaluated the flavor characteristics of seven black walnut (Juglans nigra L.) cultivars: Brown Nugget, Davidson, Emma K, Football, Sparks 127, Sparrow, and Tomboy using descriptive sensory analysis. Seven trained panelists developed a lexicon for the black walnuts and scored the intensities of the samples for 22 flavor and taste attributes. Results showed that the 7 samples differed significantly (P ≤ 0.05) on 13 of the attributes. For the majority of the attributes, only Emma K differed from the rest of the cultivars by being characterized with lower scores for black walnut ID, overall nutty, nutty-grain-like, nutty-buttery, floral/fruity, oily, and overall sweet. It also was higher in acrid, burnt, fruity-dark, musty/earthy, rancid, and bitter attributes. Researchers then incorporated the black walnut cultivars into a simple cookie recipe and evaluated the samples for differences in flavor attributes using the same trained panelists. Nine of the 25 attributes differed significantly across cultivars: black walnut ID, overall nutty, nutty-buttery, brown, toasted, acrid, rancid, overall sweet, and sweet (P ≤ 0.05). Lower mean scores in black walnut ID, overall nutty, and sweet and higher mean scores in rancid and acrid characterized the Emma K cookie. A PCA biplot revealed that cookies with Football, Sparks 127, and Sparrow walnuts related with one another and the attributes nutty-woody, leavening, and piney. A consumer acceptance test for six of the cookies (Tomboy cultivar was excluded) was also performed. There were four significant clusters of consumers that differed in their acceptance of the cookie samples. Cluster 1 preferred Football, clusters 2 and 3 each showed no overall preference, and cluster 4 preferred Emma K suggesting a set of niche consumers for black walnut cookies. Results presented in this paper can assist black walnut growers in determining which cultivars to plant and harvest. By knowing which cultivars have the most desirable flavor characteristics, growers can focus time and resources on select cultivars, therefore resulting in higher quality black walnuts as products to be sold to consumers in various formats. By consciously choosing which cultivars to harvest, black walnut growers can meet market demand and increase profit.

Master of Science / Food Science / Terry Houser / The objective of this research was to evaluate the effect of natural nitrites on objective color of vacuum packaged fresh pork. Sections of longissimus dorsi muscle (approximately 18 cm) were injected with solutions containing 0, 3, 6, 9 or 12 ppm of natural nitrite. Sections were sliced into chops (2.54 cm) and individually vacuum packaged. Raw chop surface L*, a* and b* values were measured at 1, 5, 15 and 30 days post packaging. At 1, 15 and 30 days post packaging chops were cooked and surface L*, a* and b* values were measured. Hue and Chroma values were calculated for all color measurements. Linear and quadratic contrasts were evaluated on treatments for all measured and calculated color values. A linear (P<0.05) increase was detected on the L* values for days of vacuum storage treatment, all other raw color measurements and calculations for levels of natural nitrite and days of vacuum package storage were found to be quadratic (P<0.05). Cooked L* and Hue values for days of vacuum storage were found to decrease linearly (P<0.05), all other days of storage and levels of nitrite treatments were found to be quadratic (P<0.05) in relationship to the measured and calculated cooked color values. All raw chops containing nitrite had higher a* and Chroma values at all evaluation days than those containing no added nitrite. Raw chops containing nitrite had lower L*, higher b* and Hue values than the 0 ppm chops (P<0.05). Raw chops containing natural nitrite were darker, redder, more yellow and more intense in color than those without nitrite. The longer the chops were vacuum packaged and then cooked, the lower the L* values were (P<0.05). Cooked chops containing nitrite were redder, less yellow and lower in Hue and Chroma values than cooked chops with no added nitrite P(<0.05). These results indicate that low levels of nitrite can alter fresh and cooked pork color during vacuum storage. To balance the increased redness and darkness of the raw chops with the increased redness of the cooked chops, 3 ppm of natural nitrite was found to be the optimal treatment.

Master of Science / Food Science - Animal Sciences & Industry / Fadi M. Aramouni / Food product development involves more than just creating the perfect recipe. Representatives from marketing, procurement, research and development, safety, and quality all work together to complete product development projects. This manuscript is aimed to serve food science students and professionals learning the basics of the product development process, food component functionality, basic units of food processing, regulatory considerations, food safety concepts, consumer testing, confidentiality/ intellectual property issues, and essential pieces of marketing. Many other texts concentrate on food product development, but this text looks to create a more comprehensive guide. The breadth of knowledge needed for food product development are vast. Food science students and professionals can use this text to provide basic (not exhaustive) knowledge necessary to be a valuable part of a new product development team.