Food Microbiology Commons^™

Efficacy Of Antimicrobial Treatments In Vitro And On Fresh Produce Against Selected Foodborne Pathogens And Microbiome Diversity Amongst Blueberry Farms, Angelica Maria Abdallah Ruiz

Theses and Dissertations

This study focused on evaluating the antimicrobial activity of chlorine dioxide (ClO₂) and different plant-based antimicrobials (carvacrol, thymol, and eugenol as bioactive compounds and muscadine extract- ME and blueberry extract- BBE as plant extracts) against selected foodborne pathogens under in vitro conditions and on produce (spinach and blueberries). In addition, bacterial microbiota associated with blueberries and blueberry farm environments from three different regions: Cundinamarca, Colombia; Mississippi, United States; and Guadalajara, Mexico, was determined. Under in vitro conditions, carvacrol and thymol were more effective (lower MICs and MBCs) than eugenol against Salmonella spp., Escherichia coli O157:H7 (MIC=MBC=0.2 mg/ml), and …

Microstructure And Sensory Attributes Of Rabbiteye Blueberries Subject To Osmotic Dehydration And Two Freezing Methods, Antonio Carlos Garcia

Theses and Dissertations

Frozen, thawed and osmotically-dehydrated highbush (HB) (Vaccinium corymbosum) and rabbiteye (RB) (V. virgatum) blueberries were analyzed under a scanning electron microscope (SEM) to observe microstructural differences in their skin. Rabbiteye blueberries of both frozen, thawed and osmotically-dehydrated treatments, had thicker skins than highbush blueberries. Rabbiteye blueberries, collected from local farms, packed and blast frozen (PBF), had thinner skins than individually quick-frozen (IQF) blueberries. Washing berries prior to freezing had no effect on skin thickness. Sensory analysis of samples determined there were no differences (p > 0.05) between PBF and IQF methods and species with respect to skin intactness, grittiness, sweetness, and …

Seasonal Trends And Sampling Time Of Day On Overall Microbial Population And Indicator Organisms In Catfish Parts And Catfish Processing Environment, Maria Gabriela Hidalgo-Sindoni

Theses and Dissertations

Commercial production of catfish is the leading aquaculture industry in the United States. Production in Mississippi, Louisiana, Alabama, and Arkansas representing 96% of the total catfish sales in the USA. In 2017, the USDA-FSIS added testing of generic Escherichia coli and Enterococcus to the sampling of Siluriformes. The incidence of Escherichia coli in fish and seafood has been associated with possible fecal matter contamination. However, this indicator bacteria could also be a part of the natural microflora of catfish ponds where processing plants collect hybrid catfish. Aerobes, Psychrotrophs, Coliforms, Escherichia coli, and Enterobacteriaceae counts among environmental, liquid and fish …

Antimicrobial Efficacy Of A Citric Acid/Hydrochloric Acid Blend, Peroxyacetic Acid, And Sulfuric Acid Against Salmonella On Inoculated Non-Conventional Raw Chicken Products, Emma Nakimera

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

The utilization of non-conventional chicken parts as human food varies widely across countries. The high prevalence of Salmonella, especially in the giblets, poses a high risk to public health. Poultry processors have implemented multiple hurdle technology to reduce this gram-negative pathogen in chicken parts. This study was conducted to evaluate the antimicrobial efficacy of a commercial blend of citric acid/ hydrochloric acid (CP), peroxyacetic acid (PAA), and sulfuric acid (SA) in reducing Salmonella inoculated on two chicken giblets: livers and hearts. Chicken hearts and livers were inoculated (6 log CFU/ml of rinsate) by individually immersing them in a cocktail …

Evaluation Of Biological And Chemical Seed Treatments For Management Of Rice Diseases, Sherif Adam Sharfadine

Graduate Theses and Dissertations

Rice is the primary staple for more than half of the global population and is the second most important cereal worldwide. In the US, rice is primarily grown in the southern states, with Arkansas leading production and responsible for 47% of the total rice production in the country. Diseases cause significant yield losses in rice. Sheath blight, rice blast and bacterial panicle blight are the main diseases in rice and cause significant yield losses. Sheath blight alone could cause up 50% yield loss in heavily damaged fields with highly susceptible cultivars. Additionally, rice seed and seedling diseases primarily caused by …

Evaluating Mislabeling Of Raw, Ready-To-Eat Seafood Products In Orange County, California, Courtney Kitch

Food Science (MS) Theses

Raw, ready-to-eat (RTE) seafood products have become increasingly popular globally, but they are vulnerable to species mislabeling and substitution. DNA barcoding allows for fish species identification by extracting, amplifying, and sequencing a standardized gene target. A wide variety of fish products have been studied with DNA barcoding, but notably missing are ceviche and poke, particularly in the United States. Sushi is known to be a target of mislabeling but has not been extensively studied in Orange County, CA. The objective of this study was to investigate species labeling and use of acceptable market names for sushi, poke, and ceviche sold …

Sub-Acute Oral Toxicity Evaluation Of Philippine Bignay (Antidesma Bunius (L.) Spreng Cv. ‘Kalabaw’) Fruit In Icr Mice, Jonina Marie Tengco, Liezl Atienza, Maria Amelita Estacio, Mark Joseph Desamero, Roxanne Gapasin, Jonna Rose Maniwang, Katherine Ann Castillo-Israel, Rohani Navarro, Dianne Jane Sunico, James Ryan Aranzado, Ann Cayetano, Joan Delomen, Loraine Ancheta

The Philippine Agricultural Scientist

This study evaluated the safety of Bignay (Antidesma bunius (L.) Spreng cv. ‘Kalabaw’) fruits through a sub-acute oral toxicity test in male and female ICR mice. The evaluation was done through oral gavage of the aqueous fruit sample at 2,000 mg kg^-1 body weight dose for 28 d. Results showed that there were no significant changes in feed and water intake of male and female ICR mice as compared to the control groups that received distilled water (p < 0.05). Blood chemistry and hematology values for all mice groups were comparable to the controls and published values. All mice groups also had appreciable body weight gain (10.89% – 21.69%) with zero morbidity and mortality. Lastly, the gross and microscopic examination of the brain, heart, lungs, GI tract, liver, spleen, and kidneys showed normal architecture and histology, suggesting that the fruits did not induce any morphological abnormalities. Results of this study showed that Bignay (cv. ‘Kalabaw’) fruits are safe for consumption with an LD₅₀ of greater than 2,000 mg kg^-1 body weight.

Thermal Inactivation Kinetics Of Salmonella In Milk Powder As Impacted By Water Activity And Powder Type, Erika Litta Kadas

Graduate Theses and Dissertations

Historically, low-water activity (aw) foods (aw <0.65) were considered to be microbiologically safe for consumption. However, these foods have been implicated in outbreaks of pathogens such as Salmonella enterica, at a frequency that surely challenges this assumption of safety. Although usually implicated in outbreaks involving poultry and egg products, Salmonella spp. have frequently been the culprit in several outbreaks and recalls associated with low-water activity foods (LWAF) due to contamination resulting from the environment, animals, or even the employees during pre-or post-processing. One such LWAF that has been associated with Salmonella spp. outbreaks is milk powder. Milk powders are used in a variety of products ranging from infant formula to confectionary goods. With their widespread use, improving their safety is imperative. A key step in improving their safety is to thoroughly investigate preventive controls related to milk powder processing. The Food Safety Modernization Act (FSMA) established the Preventive Controls for Human Foods Rule, which mandates that processors design and establish a food safety plan outlining any potential hazards and the steps they will take to ensure those hazards do not compromise the safety of the product. Presently, the dairy industry does not have an established kill-step for milk powders post-spray drying. Spray drying may reduce some microbial populations, however, desiccation(e.g., spray drying) is not considered a kill-step. The work outlined in this thesis aims to assist our dairy industry partners in establishing their own thermal process for milk powders post-spray drying. Moisture sorption isotherms of two milk powders (nonfat dry milk: NFDM and a milk protein concentrate with 85% protein content: MPC-85) were determined and showcased that the temperatures at which the isotherms were determined (23, 40, or 60°C) significantly affected both the adsorption and desorption isotherms (p<0.0001) for each powder. Secondly, the thermal inactivation kinetics of Salmonella spp. in both powders were evaluated at two different water activities (0.20 and 0.30) and three temperatures (75, 80, and 85°C) to determine the effect of water activity on the thermal resistance of a cocktail of Salmonella spp. The D-values of Salmonella were heavily influenced by the thermal treatment temperature (p< 0.0001), but not the water activity (p >0.05). The overall findings contained within this thesis provide valuable information about the thermal inactivation kinetics of Salmonella spp. to our partners in the dairy industry so that they may implement an appropriate thermal process for their milk powders.

Evaluating The Efficacy Of Germination And Fermentation In Producing Biologically Active Peptides From Pulses, Ashley Newton

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

Recently, there has been a profound increase in demand of plant-based proteins, especially pulse proteins. However, pulses contain high concentrations of antinutritional factors that hinder the digestibility of proteins. Processing techniques such as enzymatic hydrolysis, microbial fermentation, and physical processing modulate nutritional quality and functionality of pulses. Processing also releases peptides from parent proteins that exhibit health-beneficial bioactivity against various disease risk factors. In this study, germination, gastrointestinal digestion, and microbial fermentation were evaluated to determine the nutritional quality and release of bioactive peptides during and after processing.

Germination of chickpeas (Cicer arietinum L.) modulated the protein profile, and …

The Invisible Meat Microcosmos: Investigations Of Processed Meats' Specific Spoilage Organisms, Rebecca Furbeck

Department of Animal Science: Dissertations, Theses, and Student Research

As humankind grows in population, so will our need to compete against bacterial populations which spoil foodstuffs before we are able to consume them. This dissertation aims to identify the bacterial communities responsible for meat spoilage, and the mechanisms that govern the behaviors of these organisms. The literature review summarizes the state of knowledge regarding factors that influence meat microbiome composition, and how analytical methods can influence research outcomes. Study 1 aimed to identify the impact of additional ingredients and processing steps on the microbial ecology of processed turkey products. The main specific spoilage organisms (SSOs) belonged to the orders …

Safety Assessment Of Novel Foods And Food Proteins, Niloofar Moghadam Maragheh

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

The global food market needs to grow and supply food demand to feed the growing world population. Alternative food proteins, including novel sources of safe foods and ingredients, are the candidates that could provide more environmentally sustainable choices, animal welfare, and consumers health. Novel foods and food proteins must undergo premarket safety evaluations including allergenicity assessment to reduce the risk of cross-reactivity with known allergens and uncharacterized risk to food allergic individuals. This research addressed the safety assessment of some novel foods and food ingredients using the study of stability of proteins in pepsin and sequence identity analysis in the …

Identification Of Gut Microbiome Composition Responsible For Gas Production, Erasme Mutuyemungu

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

Gas production remains a significant barrier to increasing intake of dietary fiber-containing foods for many consumers. Therefore, this thesis is comprised of two studies focusing on the role of the gut microbiome in contributing to gas production during fermentation of dietary components. Previous studies have reported significant correlations between Megasphaera elsdenii and gas production during fermentation of pulses. Therefore, the objective of the first study was to determine the role of M. elsdenii in gas production by the microbiome during fermentation of foods commonly associated with gas production. Human fecal microbiomes were separated based on the presence (Me+) or absence …

Occurrence Of Hydroxyproline In Proteomes Of Higher Plants, Olivia Huffman

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

Food allergies affect millions of individuals across the United States and worldwide. Peanut allergies are among the most severe food allergies because of their potentially life-threatening symptoms and lifelong persistence. Potent peanut allergen, Ara h 2, is known to contain an amino acid motif containing the posttranslational modification, hydroxyproline (HyP). HyP is associated with immunogenic response when present both in Ara h 2 and in timothy grass pollen allergen, Phl p 1. To further explore the presence of HyP in higher plants and specifically to investigate its potential presence in commonly allergenic plants, a study of 26 plant seeds was …

Lactic Acid Bacteria Isolated From Fresh Vegetable Products: Potential Probiotic And Postbiotic Characteristics Including Immunomodulatory Effects, Fatima Khaled Alameri

Theses

The ability to perform effectively in the gastrointestinal system (GIT) is one of the most significant criteria for selecting the best probiotic bacteria. Thus, the present study aimed to investigate the potential probiotic characteristics of some selected lactic acid bacteria (LAB) isolated from vegetable products. Probiotic characteristics included tolerance to acid and bile, cholesterol removing ability, bile salt hydrolysis, resistance against lysozyme and antibiotics, production of exopolysaccharides (EPS), antimicrobial and hemolytic activities, and cell surface characteristics (auto-aggregation, co-aggregation, and hydrophobicity). Out of 46 isolates, 17 isolates that exhibited remarkable survivability under gastrointestinal conditions were selected for further analysis. Almost all …

Influence Of Hesperidin On The Physico-Chemical, Microbiological, And Sensory Characteristics Of Frozen Yogurt, Roberto Antonio Cedillos Hernández

LSU Master's Theses

Frozen yogurts contain yogurt culture bacteria which might impart health benefits to its consumers. Global frozen yogurt market sales are expected to grow 4.8% by 2028 which represents an important opportunity for the industry, consumers, and researchers. Polyphenols are metabolites found in plants which have antioxidant and anti-inflammatory properties and might prevent chronical diseases such as cancer, diabetes, and cardiovascular diseases. The objective of this study was to elucidate the effect of the polyphenol hesperidin on the physico-chemical, microbiological, and sensory characteristics of frozen yogurts. Hesperidin was incorporated in frozen yogurt at three concentrations (500, 250 and 125 mg/90g of …

Effectiveness Of Selected Pre-Enrichment Broths For The Detection Of Salmonella Spp. In Meat Analogs, Georgia L. Sampson, Shannon B. Ruelle, Lieuchi Phan, Donna Williams-Hill, Rosalee S. Hellberg

Food Science Faculty Articles and Research

With the increasing variety of meat analog products, it is important to verify that the methods used for Salmonella detection are effective. The objective of this study was to compare the efficacy of three pre-enrichment broths for the detection of Salmonella in meat analog burgers: the currently used Bacteriological Analytical Manual (BAM) broth (lactose broth with Triton X-100, LB-T), universal pre-enrichment (UP) broth, and buffered peptone water (BPW). Five different meat analog products (coded A-E) were inoculated with Salmonella serotypes (S. Enteritidis or S. Agona) following the Food and Drug Administration Method Modification and Method Extension Criteria for Existing …

Comparative Assessment Of Human Exposure To Antibiotic-Resistant Salmonella Due To The Consumption Of Various Food Products In The United States, Yifan Wu

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

Antibiotic resistance (AR) was increasingly recognized as a global and national problem. Prevention efforts are hampered by a lack of complete understanding of how transmission pathways contribute to human AR exposure. Many reports have indicated the presence of antibiotic-resistant bacteria in foods at retail, suggesting that food consumption, animal-derived foods in particular, can represent a significant source of AR exposure among consumers. The presence of Salmonella, including antibiotic-resistant Salmonella, has been frequently reported in terrestrial animal-derived foods such as meat, poultry, and dairy products, as well as in aquaculture products. Identification of the significant food sources that harbor …

Modeling The Impact And Accelerating The Process Of Transitioning To A Sustainable Healthy Diet Through Decision Support Systems, Prince Agyemang

Graduate Theses and Dissertations

Food production and consumption are essential in human existence, yet they are implicated in the high occurrences of preventable chronic diseases and environmental degradation. Although healthy food may not necessarily be sustainable and vice versa, there is an opportunity to make our food both healthy and sustainable. Attempts have been made to conceptualize how sustainable healthy food may be produced and consumed; however, available data suggest a rise in the prevalence of health-related and negative environmental consequences of our food supply. Thus, the transition from conceptual frameworks to implementing these concepts has not always been effective. This paper explores the …

Microbial, Chemical, And Functional Components In Kefir, Natto, And Feed Ingredients, Dana Mccurdy

All Dissertations

Kefir grains were purchased from online, home kitchen vendors in the United States (n = 22), inoculated into UHT milk, and incubated at 25°C for 22 hours. Results indicated lactobacilli, lactococci and yeast in all samples. Six out of 11 samples contained coliform, and all samples contained pseudomonal and staphylococcal species. Using targeted genome sequencing (16S) of kefir grain samples 1, 2, and 3 revealed that lactobacilli were the predominant genera of bacteria. ITS sequencing revealed different fungal species in each grain. Results indicated potential presence of menaquinone-4 and menaquinone-7 by UPLC-MS/MS analysis.

The fermentation of whole and ground soybeans, …

The Role Of Microbiota On Campylobacter Jejuni Colonization And Growth Performance In Broiler Chickens, Ayidh Almansour

Graduate Theses and Dissertations

The successful poultry production at modern era comes from the vertical integratedindustrialization, which has fundamentally changed how animals have been living for millions of years. Antimicrobial growth promoters have been used to sustain the efficient industrialized animal production, driving antimicrobial overuse and resistance. Because of the increasing pressure from consumer’s concerns and government regulations, it is urgent to develop antimicrobial free alternatives as growth promoters in poultry production, but few effective antimicrobial alternatives are currently available. Campylobacter jejuni is one of the worldwide prevalent foodborne bacterial pathogens mainly transmitted from poultry. However, few mechanisms are available on why C. jejuni …

Allelopathic Effect Of Cereal Straw Extracts On Growth Of Raphidocelis Subcapitata And Microcystis Aeruginosa, Holly Wren

Graduate Theses and Dissertations

Harmful algal blooms are increasing in size, duration, and intensity around the globe. For several decades, cereal straws have been recognized as a viable algal control method, though the mechanisms by which cereal straws inhibit algae remain a topic of research. The objectives of this study were to evaluate the effectiveness of decomposing cereal straw extract, particularly rice (Oryza sativa) and barley (Hordeum vulgare) straw extract, to inhibit the green alga Raphidocelis subcapitata or cyanobacteria Microcystis aeruginosa in bioassays and to determine if the effectiveness of decomposing rice straw extract is altered by the presence of natural organic matter or …

Chondronecrosis With Osteomyelitis In Broilers: Bacterial Species Involvement And Influence Of Probiotics And Synbiotics, Amer Abdullah Hasan

Graduate Theses and Dissertations

Since 1945, the market for broiler production has evolved from a collection of smallholder poultry farms into an industry worth billions of dollars. Poultry production has not gone without challenges. Lameness in young broilers is presently a serious issue in the poultry industry for reasons of animal health and welfare, as well as significant lost production and revenue. Bacterial chondronecrosis with osteomyelitis (BCO) is a major form of lameness in broilers. This dissertation contains information about (i) the influence of Staphylococcus agnetis, Staphylococcus saprophyticus, Staphylococcus epidermidis and Enterococcus faecalis on inducing BCO lameness, (ii) evaluation of of probiotics for reducing …

Bacterial Chondronecrosis With Osteomyelitis In Broilers: Genomics, Phylogenomics, And Methods To Detect Specific Pathogens During Outbreaks., Abdulkarim Abdulaziz A. Shwani

Graduate Theses and Dissertations

Lameness is a major issue in animal welfare and the broiler industry. Bacterial chondronecrosis with osteomyelitis (BCO) is one of the main causes of lameness. Many staphylococcal species, including Staphylococcus agnetis isolate 908, have been isolated from the bones and blood of lame broilers at the University of Arkansas. Staphylococcus agnetis is a coagulase-variable, Gram-positive bacterial species that has been previously associated with subclinical or mild clinical cases of mastitis in dairy cattle. The annotated complete genome of hypervirulent strain 908 was published at NCBI. In this study, it has been compared to nine genomes we assembled for hypervirulent isolates …

The Biological Activity Of Tea Tree Oil And Hemp Seed Oil, Lakatos Lakatos, Samuel Obeng Apori, Julie Dunne, Furong Tian

Articles

The interest in hemp seed oil (HSO) and tea tree oil (TTO) in the medical and food industries is increasing. The current study compares their bioactivity to other plant oils, mainly focusing on hemp seed oils (HSOs) with various cannabidiol (CBD) contents. A DPPH assay was employed to evaluate the antioxidant activity. The antimicrobial activity against Escherichia coli, Staphylococcus aureus, and Salmonella enteritidis was evaluated using time–kill, minimum inhibition concentration (MIC), and Kirby–Bauer disk diffusion methods. Tea tree oil showed significantly higher antimicrobial activity against S. enteritidis compared to E. coli and S. aureus (p < 0.05). The antioxitant activity range (lowest to highest) was sesame < vetiver < rosehip < tea tree < organic hemp < pure hemp < 5% CBD < vitamin C. Tea tree oil and 5% CBD showed antioxidant activity at IC50 of 64.45 μg/mL and 11.21 μg/mL, respectively. The opposing antimicrobial and antioxidant results for TTO and HSO indicate that these activities arise from different components within the oil compositions.

Development Of A Non-Dairy Yogurt Alternative Using High Protein Brown And White Rice Flour, Anita Morris

LSU Doctoral Dissertations

There is a great demand for plant-based yogurt alternatives (YAs) due to societal prevalence of milk sensitivities and allergies as well as some consumers abstaining from animal-derived products. Producing YAs from rice flour has considerable potential because (1) rice is not a major food allergen, (2) using rice flour is more economical compared to plant milks, the main ingredient in commercially available YAs, and (3) there are no rice-based yogurt alternatives in today’s marketplace. The overall goals of this study were to develop probiotic YAs from brown and white rice flours, and to evaluate their storage stability, probiotic’s survival in …

Differential Effects Of Protein Isolates On The Gut Microbiome Under High And Low Fiber Conditions, Marissa Behounek

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

Protein isolates are a growing market share in the food industry both as food ingredients and as supplements. All dietary habits can influence and alter the gut microbiome; however, little is known about how protein isolates from different sources will change the composition and function of the gut microbiota under high and low fiber conditions. The study aims to determine the microbiome response to plant and animal protein isolates under high- and low-dietary fiber (H/LDF) conditions. Six commercially available protein isolates (beef, egg white, milk, pea, and two soy protein isolates) were subjected to in vitro enzymatic digestion and dialysis …

Growth Of Foodborne Pathogens Listeria And Salmonella And Spore-Forming Paenibacillus In Commercial Plant-Based Milk Alternatives, Klaudia Bartula

ORBioM (Open Research BioSciences Meeting)

An increase in vegan diet preference, lactose intolerance, calorie concern and environmental awareness has led to a rise in the popularity of plant-based alternatives to bovine milk. Non-dairy products are a fast-growing food industry sector; however, there are still gaps in understanding how the known bacterial food contaminants behave in plant-based beverages. The present study is the first to compare the growth of food-pathogens Listeria monocytogenes and Salmonella enterica and an industrial milk product isolate, spore-forming Paenibacillus, in commercially available ultrahigh temperature processed (UHT) bovine milk and plant-based milk alternatives (coconut, almond, cashew). Beverage samples were inoculated with a strain …

Application Of Fructans-Degrading Lachancea Fermentati Fst5.1 As An Alternative To Baker’S Yeast In The Production Of A Low-Fodmap Whole Wheat Bread., Małgorzata Borowska

ORBioM (Open Research BioSciences Meeting)

FODMAPs are a group of poorly absorbed dietary carbohydrates comprised of easily fermentable oligo-, di-, monosaccharides and polyols. When consumed, they can exert gastrointestinal symptoms of pain, flatulence, or an irregular bowel movement in individuals with irritable bowel syndrome. Whole wheat bread is an excellent source of proteins, vitamins, polyphenols, and other nutrients, but its consumption is restricted in a low-FODMAP diet due to high fructans content. Although alternatives exist, these are primarily gluten-free, often inferior in terms of quality, nutritional profile, and consumer acceptance. Bioprocessing using microbial fermentation has a proven capacity to reduce FODMAPs in cereal products, but …

A Study On Plant-Derived Small Proteins And Peptides With Antiyeast Activity And Preliminary Investigations In Food Materials, Giulia Mignone

Theses

The discovery of novel antimicrobial molecules would benefit considerably different biotechnological fields, including medicine, agriculture and the food industry, on which this thesis work focuses. Specifically, here are presented fundamental studies on plant-derived antimicrobial proteins for the reduction of food spoilage caused by yeast microorganisms. Small proteins and peptides from the plant innate immune system possess several characteristics which could make them ideal candidates for a novel and natural antispoilage agent. The first Chapter reviews proteins families associated with the plant innate immune system that exhibit antiyeast activity and low molecular weight (<30 kDa), focusing on their structure and antiyeast mode of action. Chapter 2 investigates two peptides, Pn-AMP1 and Pn-AMP2 belonging to the hevein-type peptides family; peptides were synthetically generated using their native amino acid sequence. Synthetic Pn-AMP1 showed fast action activity against common food spoilage yeasts, it resulted potentially safe for consumption, and it was successfully incorporated in UHT milk and Fanta Orange, where it contained the growth of Kluyveromyces lactis and Zygosaccharomyces bailii, respectively. A different family of antimicrobial plant proteins (2S albumins) was studied in Chapters 3, 4, 5 and 6. Chapter 3 describes the selective extraction of an antiyeast protein (labelled WMS1 in this thesis work) of ~14 kDa from white mustard (Brassica hirta) seeds. The protein was purified in a relatively high yield, using a simple protocol that included only one chromatographic method step. In Chapter 4, bioinformatics tools and wet-lab techniques are used to study the structure and classify the antiyeast protein. The WMS1 antiyeast protein was identified as an isoform of the Napin protein Allergen Sin a 1 belonging to the 2S albumins family, characterised by high structural stability which donates to the protein resistance heat treatment and proteolytic degradation. Chapter 5 describes the antimicrobial spectrum of WMS1 , its antiyeast mechanism of action and its validity as preservative agent. Although WMS1 resulted potentially safe for consumption and inhibited the growth of Z. bailii in several beverage systems, its biotechnological potential is limited by its allergic properties. In Chapter 6, the protein WMS1 was cloned in a pET28a-MBP vector and expressed in an E. coli BL21 system. Interestedly, recombinant WMS1 and native WMS1 showed similar activity against the yeast Z. bailii. Thesis abstract 2 Chapter 7 includes a protocol for the rational design of ultra-short antimicrobial peptides. Since ultra-short antimicrobial sequences can be found within the sequence of any larger protein, the protocol was applied using WMS1 primary sequence, and seven ultra-short SinA-AMPs were chemically generated. Among the various SinA-AMPs, the peptide labelled SinA-pepIII had in vitro activity against several common yeast spoilage strains via membrane permeabilisation and it could be employed as a food preservative as it was pH- and heat- stable, potentially safe in terms of human consumption and it prevented the growth of Z. bailii in cranberry juice. The results obtained in this work offer new perspectives in the research for novel and clean-label food preservatives to fight the food waste phenomenon.

High Pressure Processing Of Cashew Milk, Rachel Coggins

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

Plant-based foods are becoming increasingly popular because of changing consumer preferences. Most plant-based milks are not a direct replacement for cow’s milk because they do not have the same nutritional value and physicochemical properties. However, these properties could be modified and enhanced through processing. For example, high pressure processing (HPP) can affect irreversibly protein structure and functionality and potentially enhance enzymatic hydrolysis. HPP is used widely in the beverage industry for cold pasteurization. In this study, the effects of HPP treatment on (a) the inactivation of Listeria innocua, a commonly used surrogate for Listeria monocytogenes in HPP research, in …