Nutrition & Food Science Theses and Dissertations

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    (2023) Tamia, Gillian; Lee, Seong-Ho; Nutrition; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Cancer is a major public health problem and the second-leading cause of death in the world. Colorectal cancer (CRC) is the third most diagnosed cancer in the U.S. CRC is highly associated with daily diet and eating patterns. A plant-based diet rich in phytochemicals has been known to be protective against the initiation and progression of CRC occurrence. The hop plant, a key ingredient in beer, contains a diverse form of bioactive compounds that possess biological benefits in tumorigenesis. Xanthohumol (XN), the most abundant prenylated flavonoid, has been used over the years to treat a broad range of chronic diseases such as diabetes, obesity, and cancer. Several derivatives of XN, including isoxanthohumol (IXN), 8-prenylnaringenin (8-PN), and tetrahydroxanthohumol (TXN), possess similar and greater biological benefits compared to XN. While XN's anti-cancer properties are well known, the effects of these derivatives have not been evaluated in human CRC models. Our study aimed to test the cancer-suppressive activities of these derivatives and elucidate anti-cancer mechanisms using human adenocarcinoma CRC cells. The results indicate that four hop compounds (XN, IXN, 8-PN, and TXN) significantly suppressed the proliferation of different types of human CRC cell lines. We selected TXN and XN for further studies due to their more significant and promising anti-proliferative activity compared with other forms. Flow cytometry analysis indicated that TXN and XN led to significant induction of S-phase and G2/M-phase arrest. An apoptotic assay showed a huge induction of early and late apoptosis in cells treated with TXN and XN at doses of 12 µM and 18 µM. Western blot data indicate that TXN and XN induce the cleavage of PARP and increase the expression of CHOP, IRE1α, and ATF4, indicating activation of caspase-dependent apoptosis and ER stress. In addition, a dose-dependent increase in intracellular ROS was observed in cells treated with 12 and 18 µM of TXN and XN, affecting mitochondrial dysfunction. Taken together, our current study proposes an anti-cancer mechanism by TXN and XN through their action on the induction of ROS release and mitochondrial dysfunction, ER stress, and apoptosis in human CRC cells.
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    (2023) Muruvanda, Tim; Meng, Jianghong; Nutrition; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    The longstanding problem with culture-dependent methods has been a reliance on pre-enrichment/enrichment steps which often comprise within them background microbial flora capable of outcompeting the target organism. Here, the genomic factors associated with Pseudomonas virulence and antagonism were studied in strains from selective media where it was shown to outcompete Salmonella, the target organism. 34 Pseudomonas strains of various species were sequenced and annotated. Results identified quorum sensing (QS) as the main factor of driving virulence and antagonism through the recruitment the type VI secretion system (T6SS). Additionally, two potential effectors corresponding to DUF 4225 and 4280 were found along with P.fluorescens strains containing the Pseudomonas virulence factor (PVF). These results may be valuable in the development of new strategies to better circumvent the effects of Pseudomonas in cultures.
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    Age, Nutrition, and Bone Metabolism: Analyses of Effects Using a Short-Term In Vivo Bone Model
    (1987) Sinha, Rashmi; Soares, Jos; Nutritional Sciences Program; Digital Repository at the University of Maryland; University of Maryland (College Park, Md)
    The preventative effects of dietary calcium, zinc, and vitamin D metabolites on the net loss of bone were assessed using rats of different ages. Biochemical changes were monitored in femurs, humeri, mandibles, scapulas, and tibias. In addition femora were sectioned into epiphyses-metaphyses and diaphyses to evaluate nutritional influences on the trabecular and cortical type bone. since measurable bone degradation due to aging and nutritional status requires long period of time, a short-term in vivo system was developed to simultaneously examine bone formation and resorption. The system consisted of subcutaneous implantation of demineralized (DB) and mineralized (MB) bone powders. There was evidence of bone formation and resorption in the DB and MB implants respectively, as assessed by marker enzyme (formation-alkaline phosphatase; resorption-acid phosphatase) activities, mineral concentrations, radioisotope incorporation, and histological studies. The results indicated that several different bone samples are required to adequately predict changes occurring in the skeletal system. The epiphysesmetaphyses of long bone is a useful sample site examining changes occurring in trabecular bone while the diaphysis can assess cortical bone status. There was decreased bone formation and resorption as assessed by alkaline and acid phosphatase activity in the MB and DB implants in the 24 month-old rats as compared to 2 month-old rats. Dietary calcium and zinc levels did not affect the overall status of the bones and implants in the aged rats. Conversely, in 2 month-old rats dietary calcium at 1.0% stimulated bone formation in the DB implant, whereas 0.2% calcium increased bone resorption in the MB implants. Furthermore, 75 ng dietary 1,25-dihydroxycholecalciferol (l,25(OH) 2 D) per day increased resorption in MB implant and inhibited mineralization of DB implants in the young rats. Dietary zinc at 300 ppm reduced bone calcification in 2 month-old. The results of these studies indicated that neither high levels of dietary calcium, nor zinc, act as prophylaxes to counteract bone loss due to aging. The dietary use of l,25(OH) 2 D in old animals needs to be investigated further, since results in young animals are contradictory with reports in older rats.
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    (2022) Montemayor, Abraham Moses; Tikekar, Rohan V; Food Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Ultraviolet (UV) radiation has been used in the food industry during processing, and with increased demands for safer and higher quality foods, UV-A and UV-B are being explored as antimicrobial treatments. This project consisted of three studies: the first study investigated the production of reactive oxidative species (ROS) by the action of UV radiation on fructose. The second study focused on evaluating the impact of UV-A irradiated chitosan-gallic acid (CH-GA) antimicrobial film on the quality of strawberries. The third study evaluated the effects of using UV-C individually or in combination with UV-A and UV-B to improve the fruit color and safety, respectively, of Honeycrisp apples. It is known that fructose can generate ROS under thermal treatments and UV-C (254 nm) exposure. However, it is unknown whether UV-A or UV-B exposure can generate similar effects. For the first study, fluorescein, a fluorescent dye, was used as an indicator due to its known loss of fluorescence when exposed to ROS. Varying concentrations of fructose solutions combined with fluorescein were exposed to up to 1 J/cm2 of UV-A or UV-B radiation. Ascorbic acid (AA), a known ROS scavenger, was added to the fructose-fluorescein solutions prior to UV exposure to verify ROS generation. The fluorescence was measured at 485 nm (excitation) and 510 nm (emission), respectively. A storage study was done to determine whether ROS continued to generate following UV exposure. Fructose-fluorescein solutions were exposed to 0.1 J/cm2 of UV-B radiation and stored at 4°C or 37°C. The UV-B exposure of fructose-fluorescein showed a dose-dependent fluorescence decay, whereas UV-A did not elicit this response. Fluorescein degradation followed first-order kinetics, as indicated by the rate constants. The rate constants in the presence of 10-, 50-, and 100- mM fructose were 0.7±0.01 J/cm2, 4.3±0.6 J/cm2, and 0.3±0.03 J/cm2, respectively. However, in the presence of AA, fluorescein degradation deviated from first-order kinetics. The storage study indicated no significant difference between the UV-B exposed and control solutions, indicating ROS generation ceased after UV-B exposure. The results of the studies using control solutions were extrapolated to coconut water, a commonly consumed beverage. UV-B exposure did have a degradation effect on AA, but the ROS generated did not affect the AA. The ROS was produced only when fructose was exposed to UV-B. ROS can have adverse effects on the organoleptic properties of foods containing fructose, and the addition of AA can help quench ROS in a concentration-dependent manner. The second study evaluated quality parameters such as color, texture, pH, total soluble solids, and titratable acidity of strawberries coated with an edible chitosan-gallic acid (CH-GA) coating. The strawberries were dipped in the CH-GA solution and allowed to dry. The coated strawberries were exposed to UV-A with appropriate, unexposed controls also being used for comparison. Previous studies have indicated that the coating can exhibit moderate antimicrobial activity when irradiated with UV-A at 360nm. A 180-minute exposure reduced Escherichia coli (E. coli) O157:H7 on CH-GA coated strawberries by ~2-3-log CFU/mL. However, when the quality parameters were evaluated, it was found that the UV irradiated strawberries may have been initially affected with respect to color and texture, but the loss in quality slowed down over a 14-day refrigerated storage period. It was also seen that no significant differences were observed in color and firmness between the control and experimental groups on day 14. The third study (appendix 1) aims to evaluate UV-C radiation's efficacy on the inactivation of Listeria monocytogenes (L. monocytogenes) on apple surfaces. This study was performed within the broader aim of evaluating the effects of UV-A, UV-B, and UV-C and their combinations on the quality and safety of Honeycrisp apples. UV-C radiation can serve as an antimicrobial agent, while UV-A and UV-B radiations can affect the quality parameters such as color through the hormetic effect. Therefore, our goal was to identify optimum UV-A, UV-B, and UV-C radiation doses that can be applied to Honeycrisp apples to improve their coloration and microbial safety as the marketability of apples often depends on the redness of the fruit. The UV-C dose of 7.5 kJ/m2 resulted in a 1.2±0.06 log CFU/sample inactivation of L. monocytogenes on the apple surface. Interestingly, the additional UV-C dose exposure did not result in additional inactivation. This observed lack of dose-dependence could be the result of a) UV-C penetration interference from previously inactivated microbial cells resulting in a shadowing effect, b) the formation of a biofilm during ambient air drying and 4°C incubation that provided some protection during treatment, or c) higher resistance of L. monocytogenes sub-population against UV-C inactivation. This data will allow for future exploration of a synergistic treatment that can improve the color and appearance of Honeycrisp apples and improve their safety at the same time. UV radiation has shown promising antimicrobial activity and, through the studies carried out in this project, demonstrated potential beneficial or deleterious effects on food quality. The results from the first study showed the significance of understanding the interaction of food ingredients with UV radiation. The strawberry and apple studies show that UV radiation, when used at the correct dosage, can increase, or maintain the visual appearance of the fruits, making them more marketable. When used at the correct wavelength and for the appropriate duration, UV radiation can mitigate the prevalence of foodborne pathogens and contribute to food products' quality and shelf life.
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    (2022) Mendez, Izabelle; Sahyoun, Nadine; Nutrition; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    The Expanded Food Security Screener (FSS-Exp) is a screening tool for determining food insecurity risk based on individuals’ physical, economic, and social access to food. The FSS-Exp is the only tool that provides a simple and quick method for identifying which home-delivered meal (HDM) applicants are most vulnerable. However, further testing is required to determine the tool’s validity when compared with health and food-related measures associated with food security. Therefore, this study aimed to validate the FSS-Exp and HDM prioritization tool using concurrent and construct validity methods. To evaluate the concurrent validity, we examined the correlations between the FSS-Exp and other health and food-related tools such as SF-36, MOS-SSS, SWFL, SNAQ, and DST, which were associated with economic food insecurity and physical limitation To determine construct validity using the known-groups approach, we compared those health and food-related scores among participants grouped by different access barriers to food (priority levels). The results showed that the FSS-Exp correlated moderately (r=0.20 to 0.33) with other “gold standard” measures: SF-36, MOS-SSS, and SWFL. Furthermore, our results showed that individuals categorized as priority level A and B had significantly lower mean scores than priority level E for the SF-36 (HRQL) summary measures (p<0.05), SWFL (p<0.05), and the tangible social support ( p<0.01). Thus, the FSS-Exp was shown to be a valid measure in identifying and prioritizing older adults with physical and/or economic access to food, which is especially important for HDM programs with limited resources experiencing increased demand for services. For HDM programs which exist to serve vulnerable older adults, using the validated FSS-Exp tool can help identify those who are most vulnerable and in need of immediate service.