Food Science Commons^™

The Use Of Membrane Filtration To Increase Native Whey Protein In Infant Formula, And Effects On Bioaccessibility And Bioactivity, Yihong Chen

Theses

Breastfeeding is recognised as the gold standard for feeding newborns and infants. However, infants who cannot be breast-fed or for whom breast milk is not available, can be fed with bovine infant milk formula (IMF) as a substitute. Researchers and producers of IMF strive to continually improve or “humanise” the composition and functionality of IMF. During production of IMF it must undergo several heat treatment steps, e.g. heat-sterilisation or spray-drying, in order to provide a safe product to the infant. These heat treatments denature the globular whey proteins in IMF. In contrast, breast milk is by its nature unheated, so …

Investigating Optimal Lipid:Protein Profiles For Infant Milk Formula, Valentina Ivanova

Theses

From the early twentieth century onward, much research has focused on improving infant milk formula (IMF). During the development of IMF, breast milk is commonly considered as the reference and IMF manufacturers are thriving to mimic the composition and/or to match the functionality of breast milk as closely as possible. A variety of bioactive ingredients, found in human breast milk, have been isolated and investigated for their potential functionality and utilised in the production of IMF. This study evaluated the current knowledge on compositional differences between human breast milk and IMF, and recent advances and developments in IMF production. Following …

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.

Investigating The Antioxidant, Immunomodulatory And Anti-Obesogenic Propertiesof Novel Bsg-Derived Extracts And Their Potential As Ingredients In Functional Foods For Older Adults, Suzanne O Brien

Theses

Brewer’s Spent Grain (BSG) represents a substantial waste product of the brewing industry, with 39 million tonnes generated globally every year. To date the primary use of BSG is as animal feed but there is significant interest in identifying alternative uses for this agro-industry by-product. BSG is rich in protein and fibre and is known to contain health-promoting bioactive compounds, thus one application would be in the area of functional foods. People are living longer and as the older adult population continues to increase globally so too is the prevalence of age-related chronic conditions. Diet plays an essential role in …

Isolation, Identification And Characterisation Of Enterococcus Faecalis Isolates For The Generation Of Multifuctional Bioactive Peptides From Milk, Kenneth Patrick Graham

Theses

Enterococci are lactic acid bacteria (LAB) that have the paradoxical position of possessing biochemical properties of technological importance, but are also considered as opportunistic pathogens capable of causing infection in immunocompromised patients. However, they have a long history of safe use in foods and have been evaluated in several studies for their role as starter, adjunct, probiotic and protective cultures. They show higher proteolytic activities than other LAB and have demonstrated the ability to produce bioactive peptides during the fermentation of milk. The aim of this project was to identify proteolytic Enterococcus faecalis isolates capable of generating health-promoting bioactive peptides …

Nutritional Labelling Providing Education On Its Usage Could It Impact On Patient's Food Choice Selection For Those In The Obese Classification?, Celia Lane

Theses

A build-up of too much body fat can cause significant health risks and development of medical conditions and disabilities (National Institute Clinical Excellence (NICE), 2014). The causes of obesity involve the disproportionate intake of calories that are not utilised (World Health Organisation (WHO), 2016). The rising trend towards obesity threatens to bankrupt medical systems (Heifer and Shultz, 2014). There has been a heighten awareness from the general public in the last decade of the affiliation between health and nutrition (Irish Universities Nutrition Alliance (lUNA), 2011). In light of the ever increasing obesity trend, individuals still desire to take control of …

Development And Validation Of Gas Chromatographic Methods For Free Fatty Acid Determination In Dairy Products, David Mannion

Theses

Quantification of free fatty acids (FFA) in dairy products by gas chromatography flame ion'^ation detection is an important requirement for qua'ity, research, nutritional, authenticity and legislative purposes. Common procedures are typically variants of either the fatty acid methyl esterification (FAME) or direct on-column injection methods developed more than two decades ago. This study involved the development of an alternative novel derivatization method using butylation, incorporating automation, reducing solvent usage that is applicable for a wide range of dairy products. The accuracy, precision, linearity, limits of detection and limits of quantification of all three methods were assessed for the quantification of …

Listeria Monocytogenes'. A Genomic Perspective On Its Pathogenesis, Persistence And Bacteriophages., Aidan Casey

Theses

The objective of this study was to investigate the genetic characteristics of Listeria monocytogenes that contribute to the threat it poses to the food processing industry. Transcriptomic analysis of a persistent L. monocytogenes isolate following exposure to an industrial detergent identified key upregulations in biological processes involved m peptidoglycan biosynthesis, chemotaxis and motility. Two bacteriophages against serotype 4b and 4e isolates of L. monocytogenes were isolated and sequenced. Comparative genomic and functional analysis identified the receptor binding proteins in each phage, whi]e transmission electron microscopy demonstrated a conserved baseplate architecture which also exists in other Gram­positive phages. Comparative genomics of …

Exploiting Bacteriophages And Associated Peptidoglycan Hydrolases With Potential For Biocontrol In Food Related Applications, Lorraine Endersen

Theses

The work presented in this thesis describes the isolation and characterisation of novel bacteriophages, and the subsequent exploitation of their bactericidal properties against two opportunistic food related pathogens, Mycobacterium avium subsp. paratuberculosis (MAP) and Cronobacter sakazakii.

MAP is a proven animal pathogen known to cause Johne’s disease in cattle but has been implicated as a causative agent of Crohn’s disease in humans. Despite the fact that this association has yet to be proven, significant focus has been directed towards evaluating the consequences of consuming milk contaminated with MAP. Accordingly, six mycobacteriophages were isolated and characterised in terms of temperature and …

Investigation Of Factors Influencing Trichloromethane Levels In Milk And Its Control., Siobhan Ryan

Theses

Trichloromethane (TCM) is an undesirable chemical residue that can develop in milk. While TCM levels in milk are not within ranges of public health concern, it is important that minimal levels are maintained in order to promote the marketing of Irish dairy products abroad. Germany has enacted strict regulations on TCM concentrations in foodstuffs with a recommended level of0.002 mg/kg and re-analyse those milks, subsequent to cause identification and provision of advice on reducing TCM levels in milk. Milk samples were analysed using Gas chromatography (GC) with electron capture detection. The GC method was adapted and a standard curve was …

Evaluation Of Novel Low Molecular Weight Antimicrobial Compounds Produced By Lactic Acid Bacteria., Jiahui Leona Guo

Theses

Fungal food spoilage plays a pivotal role in the deterioration of food and feed systems and some fungi are also able to produce compounds toxic for humans and animals. The mycotoxins produced by fungi can cause serious health hazards and include toxins which are cancerogenic, immunotoxic, teratogenic, neurotoxic, nephrotoxic or hepatotoxic effects and Kashin-Beck disease. In addition to this, fungal spoilage/pathogens cause losses of marketable quality and hygiene of foodstuffs, resulting in major economic problem throughout the world. Nowadays, food spoilage can be prevented using physical and chemical methods, but no efficient strategy has been proposed so far to reduce …

Development Of Pcr Assays To Detect And Characterise Salmonella Isolates From Cheese And Meat Products By Utilizing An Integrated Genomics Approach, Noelle Geraldine Mccarthy

Theses

Salmonella is an extremely important foodborne pathogen which is responsible for millions of cases of gastroenteritis annually. Salmonella outbreaks have been associated with numerous common food stuffs such as meat, dairy and seafood. Traditional culture based methods for the detection Salmonella are labourious and costly. Rapid detection and serovar identification would dramatically decrease the time required to identify Salmonella outbreaks and potential health risks.

In the US 99% of all Salmonella infections are caused by members of Salmonella enterica subspecies 1. Serovars within subspecies 1 can vary due to host specificity and pathogenicity. DNA sequencing projects have provided valuable genomic …

The Development Of Functional Food Ingredients From Yeast Cell Wall Beta Glucans, Susan Keogh

Theses

The intracellular contents of spent yeast can be used to produce flavours and flavour enhancers. However there still remains after this process, a significant quantity of cell wall material, which makes up 20-25% of the dry weight of yeast biomass. A major component of the yeast cell wall is the polysaccharide P-glucan. This project involved the investigation of the extraction and characterisation of p-glucan as well as its evaluation as a functional food ingredient. A preparation of spent yeast p-glucan was obtained from two types of spent yeast species, Saccharomyces cervisiae (brewers yeast) and Kluyveromyces marxianus (dairy yeast) obtained from …

System Identification Of A Pasteurisation Process: A Comparison Of Direct And Indirect Methods, Niel Canty

Theses

The primary focus of this research is to identify a linear model for a direct steam injection (DSI) pasteurisation process which is a component of a large-scale pilot evaporation process widely used in the dairy industry. The pasteurisation process has been identified as a key component of the evaporation process. The author believes that no previously published work has focused on identifying models for a DSI pasteurisation process which makes this work an original contribution to the area. The pasteurisation process can be modelled as a single-input, single-output (SISO) process with a measurable disturbance. Thus two transfer functions were required …