Food Microbiology Commons^™

Evaluating Variety- And Market-Class-Specific Effects Of Dietary Pulses On Human Health, Jiayu Tang

Department of Food Science and Technology: Dissertations, Theses, and Student Research

While pulses are globally recognized for their high levels of dietary fibers, protein, and polyphenols, research often focuses on characterizing the physiological effects of a single variety. This approach overlooks the substantial genetic and compositional diversity that exists across pulse varieties and individual market classes, which can differ extensively in nutrient content and structure. These compositional differences have the potential to produce distinct physiological and microbial responses in humans, yet variety- and market-class-specific effects remain poorly characterized.

This thesis uses two complementary research methodologies to investigate the health-relevant effects of different pulse varieties and market classes, providing foundational knowledge to …

Evaluating The Impact Of Region, Vintage, And Carbon Dioxide-Based Winemaking Techniques On Wine Quality Of Mediterranean Varietals, Coleman R. Imrisek

Master's Theses

Changing Vitis vinifera ripening patterns as a result of increasing climate variability has provided challenges against the production of wines with a balanced sensory profile, with adequate acidity, color, aroma, and texture. This thesis aimed to evaluate the ripening patterns and wine profiles of potentially climate-adaptive Mediterranean varietals in two different California Central Coast climates. Additionally, different carbon-dioxide based winemaking techniques were also assessed. Viognier and Grenache Noir grapes were sourced from the warmer, diurnal Paso Robles AVA and the cooler, marine Santa Maria AVA during the 2024 and 2025 growing seasons, with Syrah and Grenache Blanc grapes being only …

Examining The Ligands, Location, And Function Of Toll-Like Receptor 10, Kiefer Keanu Tam

Master's Theses

Toll-like receptors are a class of innate immune pattern recognition receptors that detect pathogen-associated molecular patterns and regulate downstream inflammatory responses. Toll-like receptor 10 remains the only human TLR whose ligand specificity, cellular localization, and immunological function are not fully defined. Emerging evidence suggests that TLR10 may play an anti-inflammatory role and can heterodimerize with TLR2 to modulate immune signaling. Previous studies from our laboratory demonstrated that stimulation with heat-killed Mycobacterium tuberculosis promotes TLR2-TLR10 heterodimerization and trafficking to the cell surface. In this study, we expanded our ligand panel to include additional gram-positive bacteria, particularly anti-inflammatory probiotic species, to further …

Advancing Targeted Food Allergen Detection: Extraction Optimization And Sample Preparation Method Comparison Using Lc-Ms/Ms, Zhenhao Wang

Department of Food Science and Technology: Dissertations, Theses, and Student Research

Accurate quantification of food allergens in processed foods by liquid chromatography-tandem mass spectrometry (LC-MS/MS) requires effective protein extraction and sample cleanup. However, no single sample preparation workflow has shown consistent performance across diverse food matrices. This study evaluated extraction buffer formulations and post-extraction cleanup strategies for quantification of milk, soy, and peanut allergens in multiple processed food matrices.

Six extraction buffers with varying combinations of SDS, urea, and thiourea alongside a common Tris-HCl/DTT/PVPP base were evaluated across five food matrices. No significant differences in extraction efficiency were observed among buffer formulations for nonfat dry milk (NFDM), non-roasted soy flour, peanut …

Detection And Quantification Of Allergen Cross-Contact In Shared Frying Oil Using Targeted Mass Spectrometry, Francisca Asigri

Department of Food Science and Technology: Dissertations, Theses, and Student Research

Cow’s milk and egg allergies are prevalent IgE-mediated food allergies that pose significant public health concerns worldwide. Although strict avoidance remains the primary management strategy, unintended exposure can still occur through allergen cross-contact, particularly in commercial and industrial food operations that utilize shared frying oils. The objective of this study was to identify and quantify allergen transfer in shared frying oil and assess the robustness of existing targeted mass spectrometry methods (LC-MS/MS) for detecting milk and egg proteins in heated oil matrices.

Heated oil spikes were developed by incorporating non-fat dry milk (NFDM) and whole egg powder (WEP) into oil …

Effects Of Fermented Soybean Products On The Human Gut Microbiome, Microbial Metabolism, And Host Physiology, Shannon Moncier

Biology Dissertations

Fermented soybean products (FSPs) contain soybean-derived substrates, fermentation-associated microorganisms, and bioactive compounds that may interact with the human gut microbiome and host physiology. However, despite the growing interest in FSPs, longitudinal human studies specifically evaluating traditional Korean-FSPs (K-FSPs), particularly among United States-based populations, remain limited. The objective of this work was to evaluate the effects of three K-FSPs, including Cheonggukjang, Gochujang, and Doenjang, on host physiological responses, gut microbial community structure, predicted microbial functional potential, and fecal butyrate responses in healthy adults. Three independent dietary intervention cohorts were conducted using FSP formulations produced either by traditional artisan methods (Product A) …

Surrogate-Based Approaches For Evaluating Post-Harvest Food Safety Interventions In Fresh Produce, Md Shafiul Islam Rion

Graduate Theses, Dissertations, and Problem Reports (ETD)

Pathogenic bacteria are still a threat to human beings worldwide as their presence is often unknown even if they are already present in fresh produces. This in turn resulted in several outbreaks and recalls across the United States. This dissertation investigated the survival of pathogenic bacteria and their potential non-pathogenic surrogates after antimicrobial interventions in different modes of applications on the surface of cantaloupes, butternut squash, and fresh cilantro. In the first study, peroxyacetic acid (PAA) was applied in three separate doses on nalidixic acid resistant Salmonella Typhimurium, Listeria monocytogenes, Enterococcus faecium, and Listeria innocua inoculated cantaloupe surfaces …

Concentration-Dependent Effects Of Green Tea Extract On The Growth And Metabolism Of Lacticaseibacillus Rhamnosus: An In Vitro Analysis, Jingxian Zeng, Francesco Noci, Kishor Keekan, Ulrich Hoeche

SURE Journal: Science Undergraduate Research Experience Journal

Green tea extract (GTE) is widely recognised for its bioactive compounds, which exhibit potential health benefits, including modulation of gut microbiota. However, the concentration-dependent effects of GTE on specific probiotic strains remain underexplored. The aim of this study was to systematically evaluate the concentration-dependent effects of green tea extract (GTE) on Lacticaseibacillus rhamnosus (L. rhamnosus). The promoting and inhibiting effects of GTE in the range of 0–50 mg/mL were analysed in vitro by OD₆₀₀ growth curve, pH change and colony forming unit (CFU) count. The experimental results showed that the concentration range of 0.05–2.05 mg/mL in the low concentration group …

Defining The Causal Contribution Of The Gut Microbiota To Cardiomyopathy Pathogenesis As A Basis For Developing Microbiome-Targeted Therapies, Xu Shi

Department of Food Science and Technology: Dissertations, Theses, and Student Research

Heart failure (HF) is a leading cause of morbidity and mortality worldwide, placing substantial clinical and economic burdens on society. Although advances in therapy have improved patient outcomes, the biological mechanisms that drive HF onset and progression remain incompletely understood. Increasing evidence suggests that the gut microbiota, the trillions of microorganisms residing in the gastrointestinal tract, plays a key role in some forms of heart disease, especially cardiovascular disease. Moreover, gut microbial dysbiosis has been associated with systemic inflammation, metabolic imbalance, and immune dysregulation, all of which contribute to the pathophysiology of HF. Cardiomyopathy, a primary disorder of the heart …

Comparative Analysis Of Probiotic Viability In Alcoholic And Non-Alcoholic Kombucha, Isabella N. Cerrone, Brooke Pirkle, Danielle Williamson, Gianna Vendrell, Chloe Kraft

Humboldt Journal of Microbiology

Kombucha is a fermented tea beverage valued for its probiotic and antimicrobial properties that arise from complex molecular interactions between yeast, acetic acid bacteria (AAB), lactic acid bacteria (LAB), and metabolic byproducts of fermentation. With the rising demand for non-alcoholic versions of traditionally alcoholic kombucha beverages, ethanol reduction methods have become common, though their impact on probiotic viability and antimicrobial properties remains poorly understood. This study investigates the effects of ethanol removal on kombucha’s functional properties, including probiotic survival, antimicrobial activity, and organic acid composition (pH). We compared alcoholic and non-alcoholic versions of JuneShine kombucha across five flavors. Probiotic viability …

Detection Method For Escherichia Coli Using Real-Time Polymerase Chain Reaction Targeting The Yhav Gene, Muktiningsih Nurjayadi, Anisa Fitriyanti, Royna Rahma Musie, Gusti Angieta Putri, Puan Aqila Azizah, Helzi Angelina, Grace Grace, Ananda Indah Putri Sihombing, Agus Setiawan, Jefferson Lynford Declan, Gladys Indira Putri, Dandy Akbar Juliansyah, Siti Fatimah, Ayu Berkahingrum, Irma Ratna Kartika, Fera Kurniadewi, Vira Saamia, Shyi-Tien Chen, Bassam Aboemolak, Hesham Ali El Enshasy

Makara Journal of Science

Escherichia coli is a foodborne pathogenic bacterium that can cause diarrhea, while yhaV is a virulence-associated gene linked to the toxin–antitoxin system in E. coli. This study was aimed at evaluating the confirmation, specificity, and sensitivity of a yhaV gene primer using real-time polymerase chain reaction. The yhaV-targeting PCR successfully amplified a DNA fragment with an amplicon length of 207 bp (base pairs) under an annealing temperature optimized to a range of 54 °C to 62 °C via gradient PCR. The PCR using the primer pair produced a consistent Ct (cycle threshold) of 14.14 ± 0.05 and showed …

Comparison Of Pcr-Based Methods For The Detection Of Canned Tuna Species, Chloe P. Castanon, Denise Hernandez, Akshay N. Khetrapal, Rosalee S. Hellberg

Food Science Faculty Articles and Research

Canned tuna is susceptible to mislabeling due to its high consumer demand, complex global supply chains, and range of prices. DNA barcoding of a short fragment of the mitochondrial control region (CR), termed the CR mini-barcode, has been established as an effective method for tuna species identification. However, the high level of DNA degradation in canned tuna products reduces the effectiveness of this method. Therefore, this study aimed to compare CR mini-barcoding to targeted (i.e., real-time or multiplex) PCR-based methods to determine the most effective approach for canned tuna species identification. DNA was extracted in duplicate from 24 canned tuna …

Assessment Of Microbial Quality And Safety, Including Aflatoxin B1, In Buckwheat Flour And Groats, La Fontaine Bahatsi

Department of Food Science and Technology: Dissertations, Theses, and Student Research

Buckwheat (Fagopyrum esculentum), a gluten-free pseudocereal, has gained popularity in global food markets for its nutritional value and functional properties. However, despite its health-promoting potential, buckwheat is vulnerable to microbial contamination and mycotoxin accumulation during cultivation, processing, and storage. These factors present significant food safety concerns that remain understudied, particularly in North America.

This study investigated the microbiological quality and mycotoxin contamination of buckwheat flour and groats collected from different suppliers via online sourcing. Samples were collected in two consecutive years (2024-2025). Microbiological quality, including aerobic plate counts (APC), Enterobacteriaceae, coliforms, E. coli, yeasts, and molds, was evaluated …

Cazyme Gene Cluster Diversity In Human Gut Microbiome, Yi Xing

Department of Food Science and Technology: Dissertations, Theses, and Student Research

In gut microbiome research, carbohydrate-active enzyme gene clusters (CGCs) have emerged as key functional units for understanding microbial glycan degradation. Unlike taxonomic or broad pathway annotations, CGCs offer gene-cluster-level resolution and capture substrate-specific microbial functions. However, their diversity and distribution in relation to host metabolic phenotypes, such as obesity, remain poorly characterized. This study tests the hypothesis that the composition and abundance of fiber-targeting CGCs vary between obese and healthy human gut microbiomes, reflecting distinct microbial carbohydrate utilization strategies. To examine this, we constructed a high-quality reference CGC dataset comprising 94,019 clusters from the Unified Human Gastrointestinal Genome and profiled …

One Health Interventions And Challenges Under Rural African Smallholder Farmer Settings: A Scoping Review, Evanson R. Omuse, Honest Machekano, Bonoukpoè M. Sokame, Daniel M. Mutyambai, Thomas Dubois, Sevgan Subramanian, Frank Chidawanyika

All Peer-Reviewed Publications

The global human population is rapidly increasing, escalating interactions of people, animals and the environment. This has led to more convoluted health challenges, for which African smallholder farmers bear the brunt. The One Health (OH) approach recognises the interconnectedness of these health challenges and thus follows a transdisciplinary approach involving diverse stakeholders to address them. Although there have recently been global concerted efforts and studies on OH, an information gap exists in Africa, particularly regarding smallholder farmers and their needs. Additionally, evaluation frameworks and outcome metrics for OH initiatives are still unclear. Thus, this study was conducted to critically map …

Decoding Bacterial Resilience: Srnas And Sigma Factors In Stress Adaptation And Persistence Of Salmonella, Anita Nguyen

Poster Presentations

Small RNAs (sRNAs) are noncoding RNA molecules in bacteria that function primarily to regulate gene expression, including those associated with stress. The Borchert Lab has identified 173 sRNAs and > 500 sRNAs that are responsive to desiccation and carbon starvation (c-starvation), respectively. Prokaryotic transcription involves an RNA Polymerase (RNAP) that transcribes DNA into RNA. RNAP involves sigma factors, which recognize promoters for the initial steps of RNA synthesis. The Borchert Lab has determined that there are significant overlaps between sRNAs expressed in cells subjected to both short-term durations and long-term durations of carbon starvation. Salmonella enterica serovars can have outbreaks associated …

Identification Of Antigens For Food Allergy And Food Allergen Detection, Ellenor Sell

Department of Food Science and Technology: Dissertations, Theses, and Student Research

Antibody-based allergen testing is an essential part of allergen management in the food industry. These methods directly detect one or more molecules of the allergenic foodstuff (target’ molecule(s)) and the presence of the allergenic foodstuff is inferred. The identity of these target molecules is crucial to the performance of the method and the interpretation of results. The goal of this study was to develop protein/antibody capture methodology for the identification of antibody binding partners using mass spectrometry.

This study is broken down into three separate projects: the characterization of the antigen-antibody complexes present in sandwich ELISAs, LFDs, and human sera. …

State Case Count As An Indicator Of Successful Multistate Outbreak Investigation, Lorisa M. Pennell

Capstone Experience: Master of Public Health

Background/Objectives: Shiga-Toxin producing Escherichia coli (STEC) is a contaminant found in multiple food types and causes multistate outbreaks due to the industrialization of food production. In this report I examine the differences in outbreaks categorized by the regulating agency responsible in outbreak prevention and compare outbreak case counts when organized by positive outbreak investigation and response outcomes.

Methods: STEC Multistate outbreak data was obtained from the Center for Disease Control’s National Outbreak Reporting System (NORS) for outbreaks occurring from 2006-2023. Outbreaks were organized into those regulated by either the US Food and Drug Administration (FDA) or the US Department of …

Inactivation Of E. Faecium Nrrl B-2354 In Whole Black Pepper By Fluidization With Hydrogen Peroxide Vapor, Daniela Segura

Department of Food Science and Technology: Master of Science with Project Option

This study evaluated Enterococcus faecium NRRL B-2354 as a surrogate for Salmonella inactivation in black peppercorns treated with hydrogen peroxide (HP) vapor via fluidization. The selected parameter for dwell temperature was 60ºC for 60 minutes. The reduction of both Salmonella and E. faecium, along with changes in water activity, color, and residual hydrogen peroxide, were measured before, immediately after treatment and at 24 and 48 hours post-treatment. Results showed that E. faecium exhibited a significantly greater reduction (4.63 ± 0.55 log CFU/g) compared to Salmonella (2.94 ± 0.16 log CFU/g) (p < 0.05), making E. faecium unsuitable as …

Aflatoxin Prevalence And Association With Maize Grain Physical And Nutritional Qualities In The Informal Markets In Meru County, Kenya, C. Cherotich, M. W. Okoth, Abong’ Go, S. W. Kariuki, E. R. Omuse

All Peer-Reviewed Publications

In Kenya, aflatoxin contamination in maize remains a persistent issue, with potential negative impacts on both public health and economic growth. Aflatoxins are toxic secondary metabolites produced by certain mold species, primarily Aspergillus flavus. The extent of Aspergillus fungal invasion in maize grains and the resulting increase in aflatoxin levels is heavily influenced by pre-and post-harvest practices. Before harvest, factors such as insect damage and exposure to warm, humid conditions increase the crop's susceptibility to Aspergillus infection and subsequent aflatoxin formation. Post-harvest, additional risks arise when kernels are damaged by pests like rats or when they are stored in unfavorable …