Food and Nutritional Sciences - Doctoral Theses

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    Evidence-based design, physiological efficacy testing and consumer analysis of an exemplar model of a fruit derived bioactive functional food for use in physical performance and exercise settings
    (University College Cork, 2023) Carey, Conor C.; Lucey, Alice; Doyle, Lorna; Department of Agriculture, Food and the Marine, Ireland
    The overall aim of this thesis is to examine the new product development practices used within the scientific design, development and testing of new nutritional products in the performance nutrition sector. Despite recent growth in the area there is a general lack of publicly available information to guide the incorporation of nutritional science into the processes underpinning the design and development of new performance nutritional products. Performance nutrition provides a promising area for the creation of value-add products using Irish agrifood outputs, a key priority in Irelands Food Vision 2030 strategy (Gov.ie - Food Vision 2030 – A World Leader in Sustainable Food Systems, 2021). In chapter 1, frameworks that were created as part of this PhD thesis to inform and guide the incorporation of nutritional science in the development of new products are introduced. These frameworks are applied throughout the subsequent chapters in the design and development of an exemplar model of a functional food to support post exercise recovery and endurance exercise performance. This exemplar model took the form of a blackberry polyphenol enriched high protein milk. Chapter 2 reviews the literature on new product development and discusses the role of polyphenols and protein in post-exercise recovery and supporting endurance exercise performance. The review confirms the efficacy of dairy protein, particularly in the form of bovine milk, for muscle repair and regeneration post-exercise. RCTs have consistently shown the benefits of consuming between 1.2-1.6g/kg/day of high-quality protein for those undergoing frequent exercise. While there's growing evidence to support the use of plant-derived polyphenols for exercise-induced muscle damage (EIMD) recovery and endurance exercise performance, gaps remain in understanding their mechanisms, dosing, and optimal dietary sources. Chapter 3 presents an online survey that assesses the nutrition priorities, practices and preferences of athletes and active individuals. This survey was designed as part of this thesis following a series of focus group sessions with athletes of various levels and backgrounds. This survey provides key end-user insights into the nutritional wants and needs of athletes and active individuals. Key findings highlight muscle recovery as the primary nutritional priority among the athletic community and reveal a clear preference for food product forms over supplements. The data collected provides invaluable guidance for new product development in sports nutrition and allows the meaningful incorporation of end-user insights into the process. Chapter 4 bridges a crucial knowledge gap by conducting a systematic review and meta-analysis investigating the efficacy of flavonoid-rich polyphenols to support post-exercise recovery. The meta-analysis of 26 randomised controlled trials (RCTs) observed significant benefits in muscle strength and soreness recovery post intensive exercise. However, a notable limitation in the included studies was the inadequate characterisation of the polyphenol subclasses and dosages used, emphasising the need for more detailed reporting in future human studies. Chapter 5 presents an RCT assessing the efficacy of the RubusElite beverage prototype to support post-exercise recovery. Results suggest that this beverage augments recovery of muscle strength and reduces muscle soreness in comparison to both high protein and low protein milks. In collaboration with RubusElite project partners, this RCT includes detailed characterisation of the beverage's polyphenol content and a verification of polyphenol stability within the treatment beverage for the study duration. Chapter 6 further investigates the efficacy of the RubusElite prototype in relation to physical performance during a 15km cycling trial. In contrast to previous findings, no significant improvement in performance or exertion-related measures was observed. However, thorough polyphenol characterisation alongside these findings offers critical insights into the lack of observed benefits and provides direction for the reformulation of the prototype. This also provides considerable insights into future RCT design to reassess the efficacy of the reformulated prototype. In summary, this thesis offers a comprehensive investigation into the development of performance nutrition products through the creation of an exemplar model using novel frameworks which allow for the incorporation of scientific best practice. It provides innovative insights into the role of polyphenols and protein in supporting exercise and is one of the first undertakings to assess their efficacy in combination. By combining rigorous scientific evaluation, consumer insights, and product prototyping, the research offers a comprehensive roadmap for future product development in the rapidly evolving domain of performance nutrition.
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    Microfiltration of skim milk: assessing serum protein removal from a mass balance and energy consumption perspective
    (University College Cork, 2023) Subhir, Surabhi; McSweeney, Paul L. H.; Tobin, John; Food Institutional Research Measure
    Application of microfiltration (MF) to skim milk as a separation technology offers a valuable source of versatile milk protein ingredients. Optimization of the microfiltration process is crucial to ensure product quality, reduce costs and enhance filtration performance in the dairy factory. An extensive review of the literature has identified gaps relative to quantification of serum protein partition dynamics and the influence of process conditions on the separation efficiency, both from a total protein and energy perspective. The objective of this thesis was to investigate the impact of filtration conditions, using both ceramic and polymeric MF systems on subsequent serum protein (SP) removal, to provide a comprehensive mass and energy balance relative to milk component separation dynamics. Initial studies using ceramic MF carried out at 50°C at a volume concentration factor of 3 (VCF3), with two diafiltration steps, established a benchmark for subsequent studies in this thesis, providing a quantitative mass balance for fractionated milk protein components and estimating corresponding energy requirements in kW h kg-1 SP removed. This study identified inaccuracies associated with standard nitrogen fraction determination and non-casein nitrogen analysis in particular, as applied to dilute/concentrated streams leading to discrepancies in protein quantification. To address this, quantitative tests were combined with complementary qualitative methods like SDS-PAGE and HPLC to provide insights into partitioning of serum proteins, which comprise both whey and caseins. Subsequent studies focused on polymeric spiral wound MF technologies, which investigated the impact of operational parameters such as membrane configuration (in-series or in-parallel), trans-membrane pressure (TMP) in the range of 75 to 120 kPa, VCF and process temperature on serum protein permeation, energy efficiency and foulant accumulation dynamics. When comparing and contrasting ceramic to polymeric MF systems under similar operating conditions (50°C, VCF3), the ceramic MF system had higher flux and cumulative SP removal rates (46 L m-2 h-1 and 90.14%, respectively) compared to the polymeric MF system (22.2 L m-2 h-1 and 62.1%, respectively). However, the ceramic MF system also required higher energy in kW h kg−1 SP removed (12.2 vs. 1.23 kW h kg−1 SP). The MF retentates produced from cold and hot polymeric MF were utilized to create whey-depleted recombined cheese milk, which altered the resultant sweet whey streams, which were subjected to in-depth compositional analysis. Sweet whey derived from MF retentate based cheesemilk had lower concentrations of whey proteins compared to traditional cheese whey along with alterations in essential amino acid composition and, in particular, threonine. Collectively, the observations and findings presented in this thesis contribute to the overall understanding of MF efficiency and quantification of fractionated milk proteins. This thesis has established a benchmark for optimizing the filtration performance of future milk protein ingredients produced by MF, providing insights into the impact of plant configuration and operating conditions on protein transmission rates, fouling behavior and energy requirements.
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    Characterising the techno- and bio-functional properties of milk protein-polyphenol complexes for application in performance nutrition
    (University College Cork, 2023) van de Langerijt, Tessa M.; Crowley, Shane; O'Mahony, Seamus Anthony; Food Institutional Research Measure
    There is increased consumer interest in performance nutrition, focusing especially on enhancing muscle strength and recovery. Dairy-plant hybrid beverages, rich in milk proteins and polyphenols, have considerable potential in this area, because both proteins and polyphenols have been positively linked to muscle strength and recovery. However, there is limited knowledge of the effects of protein-polyphenol interactions on the techno- and bio-functional properties (e.g., physical stability of casein micelles, heat stability, bioaccessibility and bioavailability) of liquid dairy systems. In these studies, the addition of polyphenols to systems containing casein micelles increased the attractive forces within the casein micelles, due to complex formation, preventing casein micelle dissociation. When milk protein systems contained blackberry polyphenols, their heat stability increased in the pH range 6.2-6.4. In this pH range, blackberry polyphenols bound calcium, which prevented protein aggregation and increased heat stability. Co-concentration of milk proteins and polyphenols was achieved by ultrafiltration, enabled by milk protein-polyphenol complex formation, allowing the complexes to be retained. Milk fat in mixed milk protein-blackberry systems positively influenced the bioaccessibility of polyphenols but had a negative effect on their bioavailability after in vitro digestion. Increasing the leucine content in these systems did not impact the bioaccessibility or bioavailability of polyphenols. In contrast, proteins increased the bioaccessibility of polyphenols and reduced the hydrolysis of polyphenols during in vitro digestion, which resulted in an increased polyphenol bioavailability. In conclusion, protein-polyphenol complexes showed considerable promise for preventing casein micelle dissociation, improving heat stability, facilitating co-concentration by ultrafiltration and improving the bioaccessibility and bioavailability of blackberry polyphenols. This new knowledge may help support the successful development of protein-polyphenol rich beverages for performance nutrition.
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    Investigations of the complex relationships between minerals, pH and heat stability in milk protein systems
    (University College Cork, 2023) Aydogdu, Tugce; O'Mahony, Seamus Anthony; McCarthy, Noel; Teagasc
    The complex composition of milk and derivatives therefrom, mean that its stability in respect to thermal treatment, while well studied, is ever evolving. Non-fat milk powders are rich in protein, of which there may be greater than 4500 different nitrogenous compounds, often present in conjunction with milk minerals. Variations in the total concentration and individual components of proteins and minerals makes dairy science a multifaceted system from which nutritional dairy products emerge, manipulated and produced by processing factors such as temperature, pressure, dehydration, shear and filtration. At the centre of dairy processing lies the most basic element fundamental to solvent chemistry; hydrogen, used as a measure of chemical reactions, but more often taken as a control parameter for physical and sensory properties. Therefore, the objective of this thesis was to advance considerably our knowledge on milk protein and milk mineral systems with regard to three main properties; heat stability, viscosity and pH changes, which have cumulative effects on dairy processing performance and finished product quality and functionality. A novel method of measuring pH at ultra-high temperatures was adapted from the pharmaceutical industry and used to examine the hydrogen ion concentration in dairy systems. For the first time, a non-linear decrease in skim milk pH was shown with increasing temperature from 25 to 140°C. The pH of skim milk decreased from 6.7 at 25°C to 6.1 at 140°C, with this reduction being reversible on cooling. This was not the case for milk permeate, where the pH remained low after sequential heating and cooling, due to irreversible calcium phosphate formation and precipitation. This highlights the stabilizing ability of micellar casein in skim milk against significant levels of calcium phosphate precipitation. However, while precipitation might be reduced, the addition of milk permeate to milk protein concentrate (MPC) resulted in substantial levels of age thickening after evaporation (45% dry matter), whereas MPC with added lactose showed no age related viscosity increase. The former system also had lower pH compared to the latter. Given the significant influence milk permeate had on viscosity of protein solutions, the heat coagulation time of commercial bulk skim milk obtained across the spring period was assessed to determine if the changes in milk composition from early lactation affected heat stability. Type B HCT-pH profiles were shown for bulk milk samples taken in February and March, compared to a type A profile for April milk, with this type A profile continuing for the remainder of the year. This is the first time that a change in HCT profile has been shown for commercial bulk milk samples; although there was no obvious difference in milk composition between any of the samples. Ultrafiltration of the skim milks was performed to obtain milk permeate fractions and was used to swap the retentate obtained in February with the permeate from April milk. This showed that a type B HCT-pH profile in February could be changed to a type A profile by simply swapping the serum phase. The outcomes of the research in this thesis are highly applicable to the thermal processing of complex nutritional formulations (e.g., infant formulas), where mineral additions and substitutions are common practice. The ability to measure pH during UHT processing is certainly a highlight of the work presented herein. In addition, a key new finding is that macro composition, specifically protein and mineral profile, is not always a good predictor of HCT, but that the serum phase of milk has the more substantial effect on heat stability than the colloidal phase on its own. The work presented in the thesis provides novel information to both the dairy industry and academia, in terms of process control through in-line pH measurement, and the fundamental effects of milk serum on protein heat stability.
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    Formulation, processing and functionality of plant-based alternatives to cheese
    (University College Cork, 2023) Grasso, Nadia; O'Mahony, Seamus Anthony; Crowley, Shane; Lauritzson Foundation
    Numerous plant-based cheese alternatives developed using different raw materials, formulations, and processes are currently commercially-available. However, most of these products differ significantly from their dairy counterparts, and a lack of knowledge of the science underpinning development of plant-based cheese alternatives is evident in the scientific literature. This thesis investigates the physicochemical characteristics of commercially-available products against dairy benchmarks and studies the influence of different protein concentrations and profiles, ingredients, and calcium fortification strategies, to achieve the development of plant-based cheese alternative prototypes with enhanced nutritional profile and functionality than these types of products currently available. Chickpea protein ingredients were used to formulate samples with high protein contents and different texture and microstructure; however, such samples did not have acceptable melting behaviour. Binary blends of zein and chickpea protein ingredients allowed development of plant-based cheese alternatives with improved meltability and stretching properties, due to the unique rheological characteristics of zein. Different calcium fortification approaches were proposed to improve the nutritional profile of plant-based cheese alternatives; however, fortification resulted in changes in the physicochemical properties of the samples. The learnings obtained were used to develop a plant-based cheese alternative prototype with similar texture to processed cheese, and enhanced nutritional and physicochemical properties compared to the commercial plant-based cheese alternatives. However, further improvements of protein digestibility and sensory properties of the prototype are needed. The findings presented in this thesis represent significant advancements in our understanding of the ingredient, formulation and processing science required to develop plant-based cheese alternatives.