Master of Science / Food Science Institute / J. Scott Smith / Acrylamide is a naturally occurring compound that is formed during the Maillard reaction. The International Agency for Research on Cancer has classified acrylamide as a “probable human carcinogen” as a result of tumor development in laboratory animals when acrylamide is ingested in high concentrations. The amino acid asparagine is particularly important in the formation of acrylamide due to its structural significance; its structure is analogous to that of acrylamide. Potato tubers contain high amounts of asparagine, thus food products such as French fries and potato chips (crisps) have been flagged for their high acrylamide levels and widespread consumption. Acrylamide mitigation in potato products can take place either during raw variety selection (or breeding) or during processing. Heating potatoes at a lower temperature or for a shorter time has shown to significantly decrease acrylamide levels. Numerous studies have shown that use of acidulants, preservatives, and low pH conditions dramatically reduce acrylamide formation by protonation of the asparagine molecule. Hydrolysis and epimerization of sugars during storage, precursor concentrations, and plant physiology are agronomic factors that can be manipulated to decrease acrylamide concentrations. Asparagine has shown to be the rate limiting factor in acrylamide formation, so processing potato cultivars with low asparagine concentrations will result in lower acrylamide levels in the finished product. Continued research areas are focusing on cultivar studies and process optimization to provide a product with lower acrylamide levels but the same sensorial attributes as current products.

Doctor of Philosophy / Department of Grain Science and Industry / Sajid Alavi / Extrusion processing is a technology widely used to make ready-to-eat snack and breakfast cereal products. The raw materials that result in optimal texture and consumer acceptance are mainly those with high levels of starch, which greatly limits the nutritional value of these products. One alternative to enhance the nutritional value is the incorporation of fruits and vegetables. Fruits and vegetables are consistently under-consumed by the American population and incorporation into extruded products may help increase the intake of important nutrients, such as dietary fiber. In the first part of this study a lab-scale twin screw extruder was used for processing directly expanded products based on corn flour and apple pomace (0-28%), resulting in a total dietary fiber content of 1.1-22.5%. Apple pomace increased nucleation and favored axial expansion. The change in cell size and alignment explained the higher mechanical resistance caused by apple pomace. The objective of the second part was to study the effect of preconditioning regimen on the extent of matrix transformation and impact on texture, microstructure and digestibility. The material was processed on a pilot scale extruder. The results showed that increasing the opportunity for hydration increased starch gelatinization at all pomace levels. Apple pomace promoted milder extrusion conditions, resulting in less starch gelatinization and solubilization and reduced starch digestibility. Digestibility was also affected by structure, with a strong correlation between the available starch fraction and cell wall thickness/cell size ratio (r=0.90). The third part of this study was designed to gain a better understanding of the impact of the individual cell wall components (cellulose, lignin, xyloglucan and pectin) on expansion and structure formation. The results suggest that compatibility with starch is critical for good dispersion in the matrix, therefore good expansion and structure forming properties.

Master of Science / Department: Food Science / J. Scott Smith / Non-nutritive sweeteners are alternative sweeteners that provide the taste of sweetness without a caloric contribution. In this Florence’s HomeStyle Cha-Cha study, aspartame, acesulfame K, sodium saccharin, and neotame were evaluated as a substitute for sucrose in the formulation. These sweeteners were used at their recommended equivalency levels to match the sweetness potency level to that of sucrose. Because they are more potent than sucrose, minimum amounts were needed to replace sucrose, and the remaining amounts were filled with maltodextrin. Using maltodextrin as bulk filler is common practice in the industry when replacing sucrose with a non-nutritive sweetener. This study evaluated the quality of the finished product in determining which non-nutritive sweetener had similar taste, aroma, and density qualities as the control, which was Cha-Cha sweetened with sucrose. The results of the evaluations indicated that Cha-Cha sweetened with acesulfame K was more similar to the control than the other non-nutritive sweeteners. Of the three taste characteristics evaluated for their degree of intensity, sweetness, saltiness, and bitterness, the acesulfame K sweetened treatment was closer to the control. In the GC/MS analysis in characterizing the volatile aroma compounds, acesulfame K contained all the aroma compounds with smaller differences in concentration than the other experimental treatments. In the density evaluation, the experimental treatments were similar to the control treatment. In conclusion, Florence’s HomeStyle Cha-Cha sweetened with acesulfame K is similar in quality to the sucrose-sweetened control.

Master of Science / Food Science Institute / James L. Marsden / Consumers demand for high quality, natural and fresh tasting food, free from preservatives and additives, with a clean label and an extended shelf life has increased. High pressure processing (HPP), also known as high hydrostatic pressure, is a non-thermal food preservation technique that has the potential to meet these demands. It is an opportunity to preserve food, by applying intensive pressure in the range of 300-900 MPa, without adversely affecting organoleptic, textural and nutritional qualities as thermal processing like pasteurization and sterilization may do. In a typical high pressure batch cycle, the food prepackaged in a high-barrier flexible pouch or a plastic container is loaded into a perforated basket that goes into the pressure vessel; the pressure is then increased to the processing target pressure (come-up time); the product is held at the desired pressure for 3 to 10 minutes (pressure holding time); after which the pressure is released in usually few seconds (decompression time) and the product can be unloaded at this point. The pressure is applied uniformly in all directions simultaneously and this is known as isostatic pressure. Pressurization is usually accompanied by a moderate and uniform temperature increase called adiabatic heating. However, the food product usually rapidly returns to its initial temperature at decompression. With the recent shift in consumer lifestyle toward healthy living and healthier food, the consumption of raw fruits and vegetables has increased in popularity. However, as per the Centers of Disease Control and Prevention, fruits and vegetables have recently been associated with multiple foodborne disease outbreaks; the effect of high pressure processing on microbial safety, quality and sensory characteristics of fruits and vegetables has therefore been widely investigated as an alternative to traditional food processing and preservation methods. HPP inactivates microorganisms and quality-deteriorating enzymes and has limited effects on covalent bonds resulting in minimal modifications of food-quality attributes such as color, flavor and nutritional values. However, depending on the fruit or vegetable, high pressure could induce chemical or biochemical reactions that can affect their quality attributes.

Master of Science / Department of Food Science / Doug Powell / In the development of a hypothetical new food product (Beta Buzz) a company must have a thorough understanding of the associated food safety risks, and control factors needed to protect their consumers and their brand. The company must understand each of the suppliers, and take a proactive approach in determining the supplier requirements. It is critical that manufacturing risks be controlled and/or reduced through a combination of internal program compliance, government regulations, third party audit compliance, and/or customer audits and expectations with a focus on ingredients, the finished product and the manufacturing process itself. Food consumers have a right to safe food; the industry, as well as the government, has a responsibility to ensure consumers receive safe food.

Master of Science / Department of Food Science / J. Scott Smith / Heterocyclic amines (HCAs) formed during cooking of meats at high temperatures are suspected cancer causing compounds and efforts have been made to reduce their levels. Spices possessing high levels of antioxidants have been shown to inhibit these compounds when incorporated prior to cooking. Seven spices, black pepper, rosemary, turmeric, thyme, cinnamon, ginger and oregano were analyzed for their antioxidant capacity using three different assays. These spices were individually added at 0.25% to beef patties fried at 400 °F for 5 min per side to evaluate their effect on HCA inhibition. Black pepper was emphasized in this study by studying the effect of addition at different concentrations (0.25, 0.50, 1.00 %) on HCA reduction. It was found that patties treated with black pepper individually, as well in combination with other spices, greatly decreased the formation of HCAs. Black pepper at 0.25% level showed the highest inhibition of PhIP levels (85%). The spices were shown to have high levels of free radical scavenging activity as measured by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. Overall, black pepper had significantly lower DPPH scavenging activity but still showed high HCA inhibition. All the spices individually inhibited HCA by 55-82%. Black pepper in combination with turmeric was the best combination, showing a 94.74% inhibition of HCA formation.

Master of Science / Department of Food Science / J. Scott Smith / The prevalence of diabetes along with the perceived impact of sugar on health in general has increased the demand for reduced-sugar and sugar-free baked products. Cakes typically contain large quantities of sucrose which affects not only flavor but also color, volume, and texture. This study evaluated the effect of replacing sucrose in white layer cakes with polydextrose and two artificial sweeteners: sucralose and stevia extract. White layer cakes were made using AACCI Method 10-90.01. Batter properties were evaluated by measuring specific gravity. Volume index was measured using a cake template (AACCI Method 10-91.01). Slice area, number of cells, number of holes, and wall thickness of the crumb were calculated and recorded using C-Cell Cake Imaging system. Control batter made with 135% water had a specific gravity of 0.90 g/cc and a cake volume index of 112. The cakes had a nicely golden brown, shiny surface. The crumb grain was fine with an even cell distribution. Optimum water level and baking time were obtained for each cake variation. Although replacing sucrose with polydextrose had no significant effect on specific gravity (p>0.05), a 25% replacement resulted in a cake with a volume index of 110, 50% with an index of 105, 75% with an index of 103, and 100% with an index of 97. The crumb grain was similar to the control cake. Adding sucralose and stevia yielded similar results, where lower volumes were recorded as polydextrose and sucralose/stevia were increased in the cake formula. Complete replacement of sucrose with polydextrose and sucralose or polydextrose and stevia produced an acceptable volume of cake. The number of holes and wall thickness of the crumb was not significantly different in any cake variation. Therefore, polydextrose and both sucralose and stevia are suitable as sucrose replacers in cakes. Key indexing terms: cakes, polydextrose, stevia, sucralose.

Master of Science / Department of Food Science / Jon Faubion / There is evolving evidence that intake of whole grains protects against development of chronic diseases. Increasing the appeal of whole grain products proves difficult as they often have poor organoleptic properties attributed to the high water holding capacity, viscosity, and insolubility of components of the bran. Amaranth is a promising grain that is naturally gluten-free and has received much attention in recent years because of its excellent nutritional profile. Studies have shown encouraging approaches to modify the molecular makeup of amaranth by enzymatic hydrolysis. This approach suggests an increase in processability and incorporation of whole grain amaranth into processed foods by ameliorating the challenges inherent in the use of whole grain flours, thereby expanding consumer acceptance and intake of whole grains. This research investigates the effects of a two-level factorial design on the enzymatic hydrolysis of whole grain amaranth with enzymes alpha-amylase, cellulase, xylanase, and protease maintaining constant pH of 6 and temperature, 50°C. The main effects show decreased viscosity and water holding capacity, and increased solubility of whole grain amaranth. The most notable findings show enzymatic treatment decreases viscosity, with alpha-amylase having the most significant impact (P < 0.0001) 21,363-59± 244 cPs. Protease was eliminated from further testing as bitterness was generated with its hydrolysate. To solubilize insoluble components, a second two-level factorial design was employed analyzing pH (4.5 and 7.5) and temperature (50°C-70°C) with the same enzyme dosage as the first design. The main effects of the second design revealed alkaline conditions significantly increase soluble fiber (P < 0.0001) 3.01-5.05% ± 0.3%. Subsequent investigation proposes a response surface design with alpha-amylase in optimizing the effects of reaction time and alkaline conditions.

Master of Science / Department of Food Science / Randall Phebus / Shiga toxin-producing Escherichia coli (STEC) are Gram negative rod-shaped bacteria that are causative agents of foodborne disease. While natural flora in the gastrointestinal tracts of bovines and other ruminants, certain enterohemorrhagic STEC strains cause serious or even fatal disease when ingested. In 2012, the USDA identified six STEC serotypes (O26, O45, O103, O111, O121, O145) as particularly dangerous (in addition to O157:H7; STEC-7) based upon data from the Centers for Disease Control and Prevention and designated them adulterants in raw ground beef, its component materials, and non-intact raw beef products. This research addressed three important components for detection of the recently declared STEC adulterant serotypes. Part one evaluated traditional E. coli O157 selective enrichment media, and additional media types and additive levels, for STEC-7 cultural amplification. Buffered peptone water (BPW), universal pre-enrichment broth (UPB), tryptic soy broth (TSB), TSB with 8 mg/L novobiocin, Escherichia coli broth (EC), and EC with 5, 8, and 20 mg/L novobiocin added were evaluated. EC broth performed equally well compared to non-selective media types, but addition of novobiocin supplement, typically used to suppress overgrowth by background flora, suppressed non-O157 STEC growth. Higher levels of novobiocin inhibited most serotypes. Part two tested the ability of transport media to maintain original STEC-7 concentrations as samples are transported to analytical laboratories. Transport media BPW, maximum recovery diluent (MRD), and Cary-Blair transport medium (CB) were inoculated with individual STEC serotypes and held at 4 or 10 °C for 72 h. Growth/survival curves indicated that CB maintained STEC-7 populations nearest to inoculation levels during storage at either temperature. Part three, part of a field study determining STEC-7 prevalence rates for cattle, hides and dressed carcasses, compared qualitative results generated by two molecular-based detection systems (BioControl Assurance GDS® and Neogen NeoSeek™), analyzing 576 selectively enriched beef carcass sponge samples collected from a commercial processing facility. The GDS and NeoSeek systems indicated 28.7 and 6.1 percent presumptive positive rates for STEC-7, respectively. It was speculated the higher GDS prevalence rate was due to false-positive determinations from the mixed culture enrichments, as viable STEC-7 cells were not recovered by immuno-magnetic bead culture isolation.

Master of Science / Food Science Institute / Elizabeth A. E. Boyle / The market for bison meat products is increasing as a result of consumer interest in meat from animals that are primarily grass fed. Quality attributes of a bison meat snack containing cranberry and apple pieces and formed into a bar or bite were evaluated during 18 weeks of storage in a 40°C accelerated shelf life cabinet to simulate an ambient shelf life of 18 months. The products were formulated at a commercial facility; bars were packaged into a vacuum package, while bites were packaged in a sealed bag with an oxygen absorber. External color, pH, sensory attributes, Warner-Bratzler shear force (WBSF), water activity (a[subscript]w), and yeast and mold populations were determined. External color, pH, and a[subscript]w were evaluated on weeks 0, 3, 5, 12, 14, and 18 of accelerated storage. Sensory attributes, WBSF shear force, and yeast and mold populations were evaluated on weeks 0, 3, 5, 12, and 18. At week 0 and week 18, external L* for the bars and bites were similar (P>0.05); however, trained panelists observed both products becoming visually darker (P<0.05) by weeks 3 and 12 for bars and bites, respectively. For bars and bites, a* values remained constant (P>0.05) through week 5 and 12, respectively, and then became less red (P<0.05) by week 14 for bars and bites. Bars continued to become less red (P<0.05) by week 18. Bar a[subscript]w remained constant (P>0.05) from week 0 through week 18, while bites a[subscript]w remained constant through week 5, and then declined (P<0.05) to a mean a[subscript]w of 0.83 by week 18. Bar pH remained constant (P>0.05) through week 5, and then declined (P<0.05) to 4.32 at week 18. Bites pH declined (P<0.05) from 4.63 at week 0 to 4.22 at week 18. Yeast and mold populations were non-detectable throughout storage for both products. Panelists found that bar bite and tenderness remained similar (P>0.05) from 4.63 at week 0 through week 18. Bites became softer and more tender (P<0.05) from week 0 to week 3, and then remained similar (P>0.05) through week 18. Bars and bites WBSF remained similar (P>0.05) from week 0 through week 18. Bar sweetness and fruit flavor intensity declined (P<0.05) and bar and bite off-flavors increased (P<0.05) by the end of storage. Changing product size from bars to bites and using a vacuum bag versus a sealed bag with an oxygen absorber influenced product characteristics during accelerated storage. The recommended shelf life for bars and bites would be equivalent to 5 months at ambient temperature based on 5 weeks at accelerated storage at 40°C.