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Publication Degradaton of Kappa-Carrageenan by Human Microbiota and Implication in Potential Pro-inflammation(2024-09) Gong, ZhijinCarrageenan (CGN) is an undigested food additive extracted from red seaweed that has been used for hundreds of years. Whether this undigested marine-derived polysaccharide will be further utilized by human microbiota remains a mystery. Fermentation of dietary polysaccharides in the human lower gut plays a vital role in maintaining the functionality and completeness of the bacterial population and host cells (1). This study aims to investigate the degradation of kappa-carrageenan (k-CGN) by human gut microbiota and its potential pro-inflammatory effects. To understand whether k-CGN was broken down by human microbiota among different individuals, seven fecal samples were collected and made into fecal slurry for in vitro fermentation. Fermentation using k-CGN as the sole carbon source happened under anaerobic conditions for 48 hours, then at 0h, 24h, and 48h time points, pH value, and total carbohydrate content were measured. Fermented samples were then cultivated on a selective medium and purified into single-strain bacteria. To determine the pro-inflammatory effect of degraded kappa-carrageenan, a supernatant of fermented samples was used to treat RAW 264.7 cells, and the level of Nitric oxide (NO) production was measured to evaluate the inflammatory response triggered by degraded k-CGN in comparison to glucose. Results of the fermentation study revealed that kappa-carrageenan can be degraded by human microflora but has individual variability. In seven samples, 3 showed evidence of breaking down k-CGN by decreasing pH value and total carbohydrate content after fermentation. The reduction of pH was due to bacteria utilizing carrageenan and producing acids. However, degradation of k-CGN by isolated single strains of bacteria remained unclear as no significant reduction of pH and total sugar content could be observed after fermentation. Results of the cell study indicated after fermentation by fecal bacteria, degraded k-CGN has a pro-inflammatory effect shown by the significant increase in inflammatory markers (e.g., nitric oxide production) in cells treated with fermentation supernatant.Publication Investigating Shear Rheology of Plant Based Hipes and their Relevance to the Printability of Extrusion based 3D Printing(2024-09) WANG, MINGHEThe popularity of plant-based foods, particularly meat analogues, has increased significantly in recent years due to health concerns, environmental considerations, and animal welfare issues. High Internal Phase Emulsions (HIPEs) is the most promising material among different fat replacement materials due to its similar appearance, viscoelastic rheological properties and semi-solid structure. However, lots of studied focus on exploring the formulation of HIPEs. Only a few studies have investigated their processability in meat analogues. A promising technique for using HIPEs in food analogues is extrusion-based 3D printing, where the processability of the edible inks critically depends on their rheological properties. Therefore, this thesis investigated the shear rheology of plant-based HIPEs and their relevance to the printability of extrusion-based 3D printing. In this thesis, coconut oil-based HIPEs were chosen as the model for edible ink due to their resemblance in appearance and rheological properties to beef adipose tissue fat. Additionally, coconut oil-based HIPEs most closely replicated the textural properties of adipose tissues. However, the phase inversion (water in oil emulsion) was observed in previous research. The formulation of coconut oil HIPEs was modified by increasing the protein concentration to avoid the phase inversion problem. Following these adjustments, stable oil-in-water coconut oil HIPEs were produced. To deepen the understanding of the relationship between the rheological characteristics of HIPEs and their printability, rheology tests and extrusion simulations were conducted for HIPEs formulated with coconut oil HIPEs. The shear rheology of the coconut-based HIPEs was thoroughly investigated. Three different approaches were used to evaluate the apparent viscosity and yield stress of the HIPEs to overcome the challenges associated with semi-solid materials like HIPEs. Firstly, the apparent viscosity was investigated using a strain-controlled flow ramp, stress-controlled flow ramp, and Cox-Merz rule methods. Among these methods, the stress-controlled flow ramp method was the most sensitive. Subsequently, yield stress was investigated using the Herschel-Bulkley model fitting, stress sweep, and amplitude sweep methods. These three methods obtained consistent yield stress values. Given their shear-thinning properties and appropriate yield stress, HIPEs were suitable for use as edible inks in 3D printing applications. To further the understanding of the processability of the HIPEs, computational fluid dynamic simulations were used to investigate the relationship between the back pressure required to maintain a given flow rate. The detailed simulations allowed for a full examination of the flow and pressure field inside a syringe during the extrusion process. The velocity profile, pressure profile, shear-rate field and viscosity-field in the syringe were determined by the simulation result. The simulated back pressure was obtained. Additionally, thixotropic tests assessed the recovery capabilities of the HIPEs. Lastly, the relationship between the rheological properties of HIPEs and their processability was constructed through experimental results derived from extrudability tests. These results indicated some differences between the simulation result and experimental data. This difference could be attributed to additional factors such as extension rheology, material elasticity, and relaxation time, which should be incorporated into the simulation models. Understanding these dynamics was beneficial for optimizing HIPEs as edible inks in 3D printing processes.Publication Rapid Detection of Titanium Dioxide in Food Products using X-Ray Fluorescence Spectroscopy(2024-09) Sankaranarayanan, PrarthanaaTitanium dioxide (TiO2) is a white, odorless, and tasteless powder used as the colorant E171 in candies, pudding, coffee creamers, etc. The potential toxicity of E171 led to its ban as a food additive in the EU starting 2022, when the European Food Safety Authority (EFSA) declared E171 as no longer considered to be safe when as a food additive, as they could not exclude genotoxicity concerns after consumption of titanium dioxide particles. However, the current regulations imposed by the US FDA only restrict the amount of TiO2 used in food, which is set at 1% by weight of the food and it is not required to be explicitly listed on the label. There are large knowledge gaps about the amount of titanium dioxide being used in food products in the US and how much of the population is being exposed to it. This study investigates the use of X-ray Fluorescence (XRF) to fill these gaps by developing a rapid and effective method to detect the presence of E171 in various food products and quantify the concentration by weight. This method will help to obtain exposure and concentration data to enable regulatory bodies to facilitate a reliable risk assessment. Since existing methods for detection such as Inductively Coupled Plasma Mass Spectroscopy (ICP-MS) are expensive, require lengthy sample preparation and utilize dangerous chemicals such as hydrofluoric acid, there is a dire need for a more rapid and cost-effective way to detect and quantify TiO2 in food. A standard curve with standards from 0.005% to 2% for quantifying the mass concentration of TiO2 was established by using a mixture of E171 with either sucrose or starch as a filling material. Sucrose yielded an excellent linear curve with r2 = 0.9962 and showed limit of detection (LOD) of 0.00059% and limit of quantitation (LOQ) of 0.00197%. A total of 40 food samples in the powder matrix were purchased from the market with and without E171 label claim and tested using XRF. Results showed the presence of E171 in 30 samples, with 16 samples having explicit label claim and 14 samples without. The concentrations ranged from 0.003% to 0.486% TiO2 with the highest category being coffee creamers and the lowest TiO2 content in seasonings. The method was validated by running the samples on ICP-MS which yielded similar results. Recovery tests were also run giving percent recovery in the range of 70%-100%. This method was also adapted to include other matrices that food products exist in, such as solid, semi-solid and liquid. Several sample preparation methods were tested for semi-solid samples. An emulsion was developed to create a standard curve with concentrations from 0.005% to 2%, which showed great linearity with r2 = 0.9959 and LOD = 0.000054% and LOQ = 0.00018%. This showed optimal results and was used for analysis of all products in this matrix. The highest concentration was found in a Queso Blanco with 0.739% TiO2. Other matrices such as solid included hard candy products, which could be quantified using the previous standard curve. This proves the ability of XRF to perform elemental analysis in a wide range of products. However, some limitations of the method include samples such as jellies and certain confectionery items which require a more specific and extensive preparation method to be used with XRF. Recovery tests were used for validation and percent recovery values from 80%-100% show that this can be a great semi-quantitative method, which is capable of screening a large number of food products for E171 in a rapid and efficient manner. An exposure assessment was also performed by considering the population consumption data from national surveys and amount of titanium dioxide present in each product. Estimated daily intake was obtained as 0.795 mg/kg bw. Overall, this study has proposed a valuable tool to rapidly and effectively detect and quantify or semi-quantify TiO2 in food and filled the existing gaps about population exposure to this additive.Publication Investigation of Plant-based and Dairy Yogurts and the Potential of Hybrid Alternatives(2024-09) Marlapati, LikhithaA key strategy employed by the food industry to enhance the sustainability of the agricultural food supply is the development of modern plant-based alternatives. Although these products are promoted as offering similar eating experiences to traditional products, consumers and researchers continue to observe differences in physical and sensory properties. To assist in creating better plant-based products, this study aimed to compare the quality and physical attributes of commercially available plant-based and dairy yogurts. Through instrumental methods, we measured pH, titratable acidity, color, water activity, moisture content, and rheology (specifically flow curves) for commercially available yogurts. The results revealed that plant-based yogurts do not differ significantly in color, moisture content, and water activity, but exhibit considerable differences in texture profile compared to dairy yogurts. Examining these differences provides the food industry with insights into the limitations and opportunities for improving the functional characteristics of plant-based yogurts. Building on this study, we hypothesized the existence of a hybrid yogurt in the market. To investigate this, we conducted an online survey to study consumer perception of hybrid yogurt and identify the main factors influencing yogurt selection. Using choice-based conjoint analysis (CBC), we presented participants with product choices based on five attributes (protein source, protein content, flavor, price, and claims) and administered questionnaires related to food neophobia and consumer values (social norms, moral satisfaction, health, and sustainability). The results of the conjoint analysis revealed that the most significant factor in the decision-making process was the protein source, accounting for 27.5% importance, followed by protein content (22.4%), flavor (20.3%), price (16.5%), and packaging claim (13.3%). The individual utility scores indicated that both dairy and hybrid yogurts had positive scores (6.1 and 6.7, respectively), while the plant-based yogurt was assigned a negative utility score (-12.8), implying a preference for dairy and hybrid yogurts. The study found a positive association between protein content and flavor with hybrid yogurt, explaining 4% of the variability, while they had a negative association with dairy. Additionally, consumer attitudes like moral satisfaction showed a negative association, explaining 0.5% of the variability. These findings indicate that consumers are open to accepting a plant-based dairy alternative that closely matches dairy yogurts. The results from both studies could contribute to the development of a product that is appealing to consumers, thus aiding consumer acceptance and promoting a sustainable diet.Publication Developing A Fluorecent Surrogate For Mimicking Bacterial Foodborne Pathogen and Promoting Sanitation(2024-09) Venigalla, NikhitaGloGerm is a commercial product that is an educational tool for public outreach on the degree of transfer of microbes to different surfaces and individuals. It is used to study sanitation practices and the transfer of contaminants from gloves to lab gear. It has several limitations because it is microplastic, not food-grade, as it contains melamine (food adulterant). Since it is not food-grade, its application needs to be revised in food-processing facilities. To overcome this limitation, we have utilized emulsion technology to develop food-grade fluorescent particles that can better mimic the properties and behavior of bacteria that may contaminate food and equipment surfaces. These novel fluorescent biomimetic particles (fBMPs) can be an easy visual indicator for sanitation and training. Curcumin, a natural polyphenol found in turmeric, is a versatile spice with various biological activities. Its fluorescent properties make it an invaluable tool for tracking and identifying substances. This system is a game-changer in food safety, primarily detecting microorganisms on food preparation surfaces. The nanoemulsion system is infused with curcumin, a fluorescent compound that can bind to any potential microorganisms on the surface. Bacteria (E.faecium) were cultured and then deposited on stainless steel coupons. These coupons were placed in a desiccator and incubated for 1 to 3 days to allow the bacteria to adhere to them. Later, the coupons were rinsed, the residue was collected in a tube, and its size and zeta potential were measured. The zeta potential of the bacterium is -32.44 mV. PP-200 & Curcumin nanoemulsion and 25 mM NaCl give the bacterium the closest charge (-37.20 mV). In the emulsions, we decreased the droplet size by increasing the pressure when the emulsion was moved through a high-pressure homogenizer by changing the (emulsifier) type or pH-controlled surface charge. Curcumin was encapsulated in a food-grade fluorophore to protect it from degradation when exposed to light. Curcumin can easily be dispersed in the oil phase of emulsions through pH-shifting method before their formation (which means their presence can be visually detected by shining a UV light on them). This work delivers a food-grade visual surrogate whose surface properties can be readily tuned to mimic pathogens of interest. Using fluorescent microbial biomimicry can provide immediate validation of cleaning protocols and simple execution.Publication Plant Based Meat: A Textural Perspective and Hybrid Products: Insights from Textual and Consumer Insight Studies(2024-05) Salgaonkar, Kashmira TusharPlant-based meat and dairy development have been the primary strategies for resolving environmental, health and animal welfare concerns. The estimated market value of plant-based meat was projected to reach $20 Billion by 2023, while the global market for plant-based dairy was valued at USD 25.19 billion in 2022. Sensory replication of animal-based meat and dairy products has been the major challenge faced by food scientists. Within the sensory domain, this study focused on the texture of different plant-proteins for use in meat and dairy alternatives. It first discussed the factors influencing the tribological behavior of plant-proteins and then compared the texture profile of commercially available plant-based hotdogs and sausages to animal-based hotdogs and sausages. The tribological study with its correlation to sensory attributes such as creaminess, slipperiness, smoothness and astringency showcased that each plant-protein exhibits distinct size, rigidity, solubility, protein and fat levels and also shows variation in its behavior with temperature. The Texture Profile Analysis (TPA) results of the 23 commercial products concluded that pea protein resulted in products with weaker structural strength while sausages and hotdogs containing a blend of soy protein and wheat gluten showed better replication to products formulated from beef and pork than pea protein. The two studies thus provided an insight into the textural domain of plant-proteins which can aid in future product development. Besides the sensory characteristics, the consumer acceptability of plant-based meat is challenged by several other product-specific and psychological parameters. Additionally, these parameters also prove to be challenging in reducing meat consumption. This study therefore conducted a consumer survey with 454 participants to determine the choice probability for hybrid meat. Hybrid meat products contain a blend of meat and plant-protein and are considered as a potential in reducing meat consumption. However, the results of a choice-based study known as conjoint analysis showed that hybrid meat hotdogs had the lowest preference in comparison to pure plant-based and pure meat hotdogs. The regression analysis determined that the product-specific attributes challenged the choice for hybrid hotdogs, while person-related parameters did not have any relationship, which was contrary to the results obtained for plant-based and beef hotdogs. This influence of the different parameters on the selection of hybrid meat was concluded to be due to the lack of consumer knowledge and familiarity with hybrid products.Publication Fat Lowering Effects of Daphnetin in Caenorhabditis Elegans(2024-05) Noh, SuyeunDaphnetin is a coumarin derivative, extracted from the different Daphne species, known to have anti-cancer, neuroprotective, anti-obesity, anti-inflammatory, anti-bacterial, and anti-malarial effects. However, the research on the anti-obesity effect of daphnetin is limited. Therefore, this study was conducted to determine the effects of daphnetin on lipid metabolism using an in vivo model, Caenorhabditis elegans. Treatment of 100μM daphnetin reduced fat compared to the control in wild-type C. elegans. The pumping rate has not been affected by daphnetin, suggesting daphnetin does not affect the food intake of worms. The bending rate also has not been affected, suggesting daphnetin does not affect the energy expenditure of worms. Mutants were tested to determine the fat-reducing mechanisms of daphnetin. The daf-2, daf-16, and aak-2 null mutants didn’t show a decrease in fat by daphnetin, suggesting daphnetin regulates fat accumulation in part via DAF-2, DAF-16, and AAK-2 dependently.Publication Evaluation of Blackberry Cultivars and Blackberry-Pear Synergies for Potential Management of Type Ii Diabetes and Hypertension(2012-09) Warner, Stephen DThe incidences of diabetes are on the constant rise, and thus need an alternative dietary approach to improve glucose metabolism in type II diabetes patients. Fruits and vegetables have long been known for their beneficial fiber, phenolics and antioxidants, and by incorporating these dietary components into our everyday diet have proven beneficial in controlling the glucose metabolism. In this study, Prime-Jan and Kiowa blackberry cultivars were evaluated for their anti-diabetic properties using a variety of in vitro assays. Overall, the Kiowa blackberry reigned supreme over the Prime-Jan blackberry in the majority of functionality assays, more specifically alpha-amylase, alpha-glucosidase, total soluble phenolics and DPPH free radical scavenging activity. In an attempt to incorporate anti-hypertensive properties into this study, we chose to integrate the Bartlett pear, known as the most widely consumed pear in the United States and recognized for its moderate ACE inhibition. Our results indicated a combination of 70% pear to 30% blackberry as the most beneficial ratio for exhibiting high alpha-amylase (96.5%) and alpha-glucosidase inhibition (95.6%). Additionally, the 70/30 combination exhibited high DPPH free radical scavenging activity (80.7%), total soluble phenolics (1.9 mg/g FW), while also maintaining moderately high ACE inhibition (25.2%). Therefore, there is vast potential for a combination of 70% pear to 30% blackberry to serve as a beneficial alternative in the diet of patients suffering from type 2 diabetes.Publication Accessing The Bioavailability Of Phytochemicals In Caco-2 Cell Model And Developing A Sensitive Method For The Detection And Quantification Of These Compounds(2012) Sobers, Hana ShataraNumerous studies have found certain unmethylated phytochemicals to possess anti-carcinogenic activity; however, they have been associated with poor oral bioavailability which is a major limiting factor in their usage in chemopreventative treatment. The purpose of this study was to investigate if methylation of a compound would affect bioavailability, in terms of transport and permeability, in a Caco-2 cell model as well as the effect of cell viability and cellular uptake in human colon cancer cell lines. Furthermore, a new analytic method using reversed-phase high performance liquid chromatography coupled with electrochemical detector (HPLC-EC) for the detection and quantification of resveratrol and pterostilbene was developed. This new method was simple, rapid, and more sensitive compared to other detection methods used to analyze resveratrol and pterostilbene. Linear range, limit of detection (LOD), precision and recovery were used to validate this new analytical method. There was a significant increase in intracellular uptake and stronger growth inhibitory of pterostilbene in human cancer cells lines in comparison to resveratrol. Resveratrol exhibited a higher and more rapid rate of transport than pterostilbene across the Caco-2 monolayer regardless of the concentration tested and direction. Pterostiblene exhibited little difference in the rate of transport from either direction. The HCT-116 colon cells had intracellular uptake of each of the polymethoxyflavones (PMFs) tested. Transport was observed by all the PMFs and each had different rates of transport. Overall, location and amount of methyl groups had an effect on bioavailablity of a compound and these compounds show promise as chemopreventative agents.Publication Synergistic Approach for Designing and Enhancing Bioactive Ingredients from Apple and Blueberry for the Management of Early Stages of Type 2 Diabetes(2012-05) Agustinah, WidyaType 2 diabetes is a worldwide and costly disease that requires complex cellular metabolic breakdown for its development. The onset of this disease is indicated by an abnormal elevated blood glucose level (hyperglycemia) and coexistence with hypertension. Apple and blueberry are the two popular fruits in the U.S. that are high in bioactive phenolic compounds. The objectives of this thesis were to investigate the synergistic health benefits of apple cider and blueberry juice for potential management of early stages of type 2 diabetes using in vitro enzyme assay models and enhance their synergistic effects through fermentation using probiotic strains of lactic acid bacteria. Apple cider and whole blueberry juice were combined at 5 different ratios. Synergistic interaction of the phenolic bioactives between the two juice sources was observed in all assays. For maintenance of high α-glucosidase, α-amylase and ACE inhibition activities, a proportion of 80% apple cider and 20% whole blueberry juice was selected as the optimum combination reflecting maximum health benefits to potentially manage hyperglycemia and hypertension associated with type 2 diabetes. The 80/20 apple cider and blueberry juice combination was fermented at 24 and 48 h using Lactobacillus helveticus R0052 and Bifidobacterium longum isolate. High inhibition of α-glucosidase, α-amylase and ACE enzymes was observed in apple cider/blueberry juice combination. Strong antimicrobial activity against H. pylori was exerted by L. helveticus- and B. longum-fermented sample at 48 h. A possible mode of action through the synergy between lactic acid and proline oxidation pathway was suggested.Publication Development of a Novel Lateral-Flow Assay to Detect Yeast Nucleic Acid Sequences(2012-05) Fill, Catherine EAs demand for food increases, rapid testing methods are becoming increasingly important. In the past few years, yogurt has become popular. Yeast species are the most common spoilage organism, costing consumers and food companies money. A novel lateral flow assay has been developed to detect yeast oligonucleotide sequences. Gold nanoparticles were used as the standard reporter and fluorescent nanoparticles were developed as the novel reporter. The fluorescent nanoparticles were ruthenium-doped silica nanoparticles synthesized using the modified Stöber method. Visual analysis of assays using standard reporters showed the limit of detection to be 10 femtomoles of target sequence. Analysis of the fluorescent nanoparticles using a plate reader showed the limit of detection to be 0.027 femtomoles. The fluorescent reporter’s limit of detection is 1000 fold lower due to a sophisticated, more sensitive analysis method. Gold nanoparticles are appropriate for presence or absence testing, but fluorescent nanoparticles are best for obtaining quantitative data with low detection limits. Pathogens have been used as biological warfare for centuries. A brief review of common biowarfare agents is included. Yersinia pestis, the causative agent of the Plague, and Bacillus anthracis, the causative agent of Anthrax, are the focus. Additional work using gold nanoparticles as reporter in a sandwich assay is also included. The novel dye covered reporter was compared to the control, which was a single dye molecule linked to the reporter sequence. Repeated testing showed the novel reporter had a lower limit of detection and higher sensitivity due to increased ability to bind target.Publication Purification and Characterization of Novel Nucleases from a Thermophilic Fungus(2012) Landry, Kyle SA thermophilic fungus was isolated from composted horse manure. The organism was as a Chaetomium sp. by sequencing the highly conserved ITS region of the fungus and comparing to known regions in a genomic database and was referred to as TM-417. TM-417 was found to have an optimal growth temperature of 45 oC and an optimal pH of 7.0. An extracellular DNase and RNase was found to be produced by the isolate and were purified 145.58-fold and 127.6-fold respectively using a combination of size exclusion chromatography and a novel affinity membrane purification system. The extent of purification was determined electrophoretically using 4-15% gradient polyacrylamide gels. Both DNase and RNase were dependent on metal co-factors for activity. The metal ion Mg2+ was the preferred ion for the DNase, whereas for the RNase, Zn2+ and Mn2+ yielded an increase in enzyme activity over that with Mg2+. The purified DNase demonstrated maximum activity at pH 6.0 with no activity at pH 2.0 or 10.0. The RNase exhibited two peaks of maximum activity, on at pH 3.0 and the other at pH 7.0 with no activity at pH 2.0 or 10.0. The optimal temperature for the purified DNase was 65oC. The optimal temperature for the RNase was 70oC. The molecular of the DNase and RNase were determined to be 56 kDa and 69kDa respectively using a Sephadex G-75 column. A standard curve was generated using several standard proteins of known molecular weight.Publication The Effect Of Curcumin (Curcuma Longa) On Biofilm Formation And Surface Proteins Of Listeria Monocytogenes(2012-02) Ruengvisesh, SongsirinThe food-borne pathogen Listeria monocytogenes can attach to the environmental surfaces and develop biofilm which can cause food contamination in the food industries. Sortase A and surface proteins are involved in biofilm and virulence of L. monocytogenes. Curcumin was reported to inhibit sortase A and biofilm in gram positive bacteria. The overall objective of this study was to observe the effect of curcumin (Curcuma longa) on the biofilm formation and surface proteins of L. monocytogenes. The antibiofilm effect of curcumin against the strain LM21 (wild type) and s22-11G (sortase A defective mutant) was studied using the microtiter plate assay. No significant differences between the growth of the wild type and the sortase A defective mutant were observed at sub-inhibitory concentrations of curcumin. However, a greater biofilm reduction was observed in the strain s22-11G. The effect of curcumin from two different manufacturers on the wild type was also compared by the microtiter plate assay. Both curcumin did not exhibit statistically different effect on the growth of the wild type. However, a greater biofilm inhibitory effect was observed in one curcumin. The HPLC results suggested that curcumin with the greater antibiofilm activity contained higher amount of curcumin which was reported to be the most potent curcuminoid compound in curcumin. Three different protein extraction methods were evaluated and the most efficient method was used for 2D-GE. When cells were grown in the presence of curcumin, 5 proteins, 16 proteins and 4 proteins were up-regulated, down-regulated and absent, respectively in L. monocytogenes LM21. The influence of the enzyme sortase A upon surface protein expression was evaluated by comparing proteins expressed by wildtype L. monocytogenes LM21 to that of the sortase A mutant, s22-11G. In strain s22-11G, 2 proteins, 8 proteins and 3 proteins were up-regulated, down-regulated and absent in comparison to wildype LM21. The exact information of these differentially expressed proteins still need to be identified by mass spectrometry.Publication The Effect of Cooking on Formation of Bioavailable Species of Iron from Chicken Breast Muscle(2011) Gokhale, Aditya SChicken breast muscle was cooked to an internal temperature of 165oF by four methods: boiling, baking, sautéing and deep-frying. All cooking methods led to a decrease in formation of dialyzable iron, formed by both extraction and digestion in vitro, compared to raw muscle. After cooking most of the dialyzable iron formed results from extraction and the formation of dialyzable iron by digestion is essentially eliminated. Cooking also decreased the levels of cysteine and histidine; these losses may contribute to the loss in dialyzable iron.Publication Transfer of Listeria Monocytogenes from Stainless Steel and High Density Polethylyene to Cold Smoked Salmon and Listeria Monocytogenes Biofilm Cohesive Energy Investigation(2011-05) Zhang, FujiaListeria monocytogenes is a major concern for the food industry. It is one of the major agents causing listeriosis. The objective of the first part of this study is to evaluate the effect of hydration level on attached listeria monocytogenes on stainless steel/High density polyethylene transferred to food products. Attached cells were prepared on stainless steel/High density polyethylene. Transfer experiments were conducted from inoculated surface material slides to cold smoked salmon fillets. This experiment was repeated 6 times. The results were analyzed with an analysis of variance by SAS. The differences between the different RH% and surface conditions were not statistically significant. There was variability in between packages, brands and over the course of storage after opening, and likely contributed to the variability of transfer observed in this set of experiments. The objective of the second part of the research is to study the effect of hydration level on the detachment of Listeria monocytogenes biofilm growing on stainless steel by using Atomic force microscope. Biofilms were grown on stainless steel in drip flow bioreactor at 32 °C for 72 h. Then biofilms were equilibrated over saturated salt solution at 20 °C for 48 h before the Atomic Force Microscope experiment. The results showed that cohesive energy value of the biofilm increased with biofilm depth. Only square shaped displaced 2.5X2.5 μm region were visualized after serious of raster scanning under high load which means that moisture condition of Listeria monocytogenes biofilm can significantly affect the cohesiveness between of Listeria monocytogenes biofilm.Publication A Multidisciplinary Approach to Food Safety Evaluation: Hummus Spoilage and Microbial Analysis of Kitchen Surfaces in Residential Child Care Institutions (rcci) in Massachusetts, U.S.A.(2011-05) Hagan, Elsina E.Food borne illnesses continues to be a public health challenge in the United States (U.S.); an estimated 9.4 million incident cases occurred in 2011. In view of this challenge we conducted two food safety studies; 1) related to product formulation (hummus spoilage challenge study) and 2) evaluating the microbial safety of domestic kitchen surfaces in Residential Child Care Institutions (RCCI pilot study). Hummus is of Mediterranean origin but is currently eaten globally. This challenge study evaluates a variety of industrial hummus formulations (four in total, differing in pH and/or addition of a preservative (natamycin). Two batches were setup: batch 1; aseptically inoculated hummus with 100 CFU/g fungal isolates and batch 2; uninoculated hummus. Samples of both hummus batches were stored at both 20oC (10 days accelerated testing) and 4oC (84 days recommended temperature testing). Inoculated samples were analyzed for fungus, whiles both fungi and bacteria (standard plate count (SPC) and Lactococci) counts were done for uninoculated samples. Results indicate that accelerated testing inaccurately predicts fungal growth at 4oC in hummus, also fungal growth inhibition requires a pH ≤ 4.0 ± 0.2 and refrigeration. Limited studies have specifically evaluated the prevalence of pathogenic bacteria in domestic kitchens in the U.S, for this reason we assessed the microbial safety of 6 RCCI locations in MA. Fifteen key food contact surfaces and dish washing sponges, if available at each RCCI facility were assessed for SPC, yeast and molds, total coliform and E. coli, Listeria sp and Salmonella sp. Microbiological assessments were conducted preceding and after a hazard analysis and critical control point (HACCP) food safety training and implementation at each location. Microbial growth varied by surface for each type of microorganism, wet surfaces had higher most probable number (MPN) counts. Compared to dry surfaces, wet surfaces had significantly higher mean total coliform counts. For both E. coli and total coliform, microbial load differed significantly by surfaces sampled (P = 0.0323 and 0.014) respectively. The surface and training interaction effect was highly significant for only E. coli (P = 0.0089). Training overall had no significant effect on reducing the microbial load on kitchen surfaces.Publication Antagonism of Serratia plymuthica against Gram negative food-borne pathogens (Escherichia coli O157:h7 and Salmonella Enteritidis)(2011-02) Ememu, Ejovwoke FBacteriocins are antimicrobial protein produced by certain Gram positive and negative bacteria as a defense mechanism against closely related bacteria competing for the same nutrient or in the same niche. The competition for the same nutrient is supported by the fact that bacteriocins have narrow range of effect and only likely to be effective against closely related bacteria for the same scares resources hence a bacteriocin produced by a Gram positive bacteria will be active against a Gram positive pathogens and a bacteriocin produced by a Gram negative bacteria will be active against Gram negative pathogens. This is due to the difference in cell wall composition, they are either bacteriocidal or bacteriostatic Bacteriocins have been used for thousands of years for food preservation unknowingly to man, they are considered advantageous not only to the producing bacteria, but it's now been used by the food industry as a tool to control both spoilage and pathogenic bacteria in food, in a natural manner which is acceptable to the consumer. With a lot of research been carried out on bacteriocins produced by Gram positive bacteria, antagonist to Gram positive food borne pathogens, little is known about bacteriocins produced by Gram negative bacteria which would be active against Gram negative food borne pathogens that predominate in produce. The objective of my research therefore is to screen for antimicrobial antagonist to Gram negative food borne pathogens (Escherichia coli O157:H7 and Salmonella Enteritidis) from produce, to determine an appropriate screening method, to carry out a preliminary characterization of antagonist discovered and also to determine antimicrobial spectrum of antagonist found. Lettuce was screened for antimicrobial antagonist against Gram negative pathogen (Escherichia coli O157:H7 and Salmonella Enteritidis) which were used as indicator strains With over 5000 colonies screen, 1 colony (Serratia plymuthica) was discovered to be antagonistic against these indicator strain. Further screening of cell free extract using the spot test method showed that extract from Serratia plymuthica grown alone in TSBYE showed antagonist activity against indicator strain with a little clearing on the spot of extract dropped. But extract of a co-culture of Serratia plymuthica and either Escherichia coli O157:H7 or Salmonella Enteritidis showed a more obvious clearing around spotted zone, which further indicates antagonism against indicator strains. Preliminary heat test indicates antagonist compound to be heat stable at 60oC for 30mins, 100oC for 30minutes and 60mins and 121oC for 20minites, and antagonist compound possessed antagonist activity against other strains of Escherichia coli when tested.Publication Encapsulation of Curcumin in O/w Nanoemulsions and Its Bioaccessibility After In Vitro Digestion(2010-09) Ahmed, KashifThe functional ingredient curcumin has a variety of biological and pharmacological actions, such as anti-tumor, anti-inflammatory, anti-virus, anti-oxidant, and anti-HIV properties coupled with low toxicity. However, curcumin possesses low bioavailability due to its poor solubility in water. The purpose of this study was to investigate the impact of different lipid-based formulations of curcumin on in vitro solubilization and bioaccessibility. Oils representing LCT, MCT, LCT:SCT mix and SCT were used to prepare O/W (nano)emulsions with droplet sizes as low as 174 nm. An in vitro digestion model simulating the small intestine milieu in the fasted and fed state was used to characterize rate, extent, and particle size associated with emulsion digestion. Rate and extent were oil dependent, but not particle size. SCT emulsions digested at the fastest initial rate, but MCT emulsions were digested to the largest extent. Bioaccessibility, a precursor to eventual bioavailability, was determined after digestion using a curcumin:lipid content dependent and independent method. MCT produced the highest bioaccessibility of curcumin for each method. Nanoemulsion digestion and bioaccessibility results were compared to conventional emulsions because an appropriate comparison was needed to determine the merits of the nanoemulsion delivery system. There was no significant difference in particle size and bioaccessibility between the conventional and nanoemulsions.Publication The Effects of Conjugated Linoleic Acid Isomer on Tumor Suppression(2010-05) Wong, Janice YSarcoma is a type of cancer in the connective tissues including bone, cartilage and adjacent adipose tissue. Osteosarcoma is a type of sarcoma specific to bone, as “osteo” comes from the Greek work, “osteon,” or “bone.” Osteosarcoma is a typically aggressive type of bone-forming mesenchymal cancer/ bone malignancy which comprises approximately 20% of primary bone cancers and 5 % of pediatric tumors overall. Four hundred children and adolescents are diagnosed with osteosarcoma in the US each year. Although the survival rate of patients with osteosarcoma has improved over time, osteosarcoma is still the second highest cause of cancer-related deaths in the pediatric age group. This is due, in part, to an inherent or acquired resistance to the chemotherapeutic agents, so it is critical to develop treatment strategies to prevent and/or treat this type of cancer. Conjugated linoleic acid (CLA) is a collective term used to describe positional and geometric isomers of linoleic acid, in which two double bonds are in conjugation. It occurs naturally in many dairy and meat products of ruminant animals. Upon the discovery of CLA as an anticancer component in the 1980s, CLA has been shown to be an effective prevention tool in a number of animal cancer models. It has been suggested that one of the main targets of CLA is non-steroidal anti-inflammatory drug-activated gene 1 (NAG-1), which is a key regulator of apoptosis. Thus, the overall goal of this proposed research is to determine CLA’s anticancer effect with the involvement of NAG-1 in an osteosarcoma model.Publication Colloidal Particles as Antimicrobial Carrier Systems(2007) Carnahan, Dustin WThe objective of this thesis is to develop a method by which antimicrobials are delivered into a food product as a concentrated dose to the specific area in which the microorganism is growing without interference from the food matrix. More specifically, we plan to achieve this by delivering the antimicrobials nisin and lysozyme attached to nanoparticles and emulsion droplets. We hypothesize that (a) the attachment to a delivery vessel may increase the local concentration of the antimicrobial in the vicinity of the bacterial pathogens and (b) that the size and charge of the nanoparticle following attachment of the antimicrobials will be critical to its efficacy against pathogens. This thesis is designed to test this hypothesis using silver nanoparticles with well defined sizes and surface chemistry that allow control over the loading of the particle and oil droplets to which nisin is a secondary layer attached to pork gelatin which acts as the primary emulsifier.