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    Investigating the health benefits of Monty’s Surprise apple phytochemicals : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Nutritional Science at Massey University, Manawatū, New Zealand. EMBARGOED until 18 November 2027.
    (Massey University, 2024) Nezbedová, Linda
    Cancer is a major health concern worldwide, requiring effective prevention strategies to reduce its burden. There is evidence suggesting that diet plays an important role in disease prevention. Apples are an example of a commonly available fruit that can be easily incorporated into a diet to reduce the risk of chronic disease and some cancers. Apples are rich in phytochemicals with chemo-preventative properties. However, assessing their benefits in humans is complex due to various factors affecting phytochemical composition and low bioavailability. Understanding and controlling for these factors is crucial for maximising their potential in preventing cancer and promoting human health. The PhD project presented in this thesis uses a multidisciplinary ‘from orchard to fork to function’ approach to evaluate the health benefits of phytochemicals in a New Zealand heritage apple cultivar known as Monty’s Surprise, with an emphasis on cancer prevention. This thesis particularly focuses on apple’s most abundant phytochemical group known as phenolic compounds. After controlling fruit harvest and maturity, Monty’s Surprise apple was found to contain high concentrations of health beneficial phenolics, especially procyanidins, with apple skin having higher total phenolic content compared to its flesh. Pureeing was identified as a suitable processing technique with minimal impact on apple’s phenolics, allowing long-term preservation and creating uniform material for use in intervention and feeding trials. Moreover, Monty’s Surprise apple extract depleted of sugars inhibited the proliferation of lung, breast, and colorectal cancer cells in a dose-dependent manner in vitro. Lastly, in a human acute feeding trial, Monty’s Surprise apple puree increased plasma antioxidant capacity and decreased postprandial glucose response compared to sugar-matched placebo. The feeding trial also showed that procyanidins were not detected in the participant’s blood, while epicatechin and chlorogenic acid, which are prevalent phenolics in Monty’s Surprise apple puree, were absorbed into the bloodstream. Therefore, these compounds were available to contribute to the improved health parameters measured in the study. This study offers practical recommendations for optimising harvesting, storage, and processing practices to preserve and more clearly elucidate the health-promoting properties of phenolics in apples. Overall, this research demonstrated the potential health benefits of Monty’s Surprise apple and its phenolics, suggesting its value as a functional food for improving human health and well-being.
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    Characteristisation of acetic acid bacteria and yeast isolated from kombucha produced in New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Food Technology at Massey University, Auckland, New Zealand. EMBARGOED until 21 August 2026.
    (Massey University, 2024-08-13) Wang, Boying
    Background: Kombucha is a popular functional tea beverage commonly fermented by a complex symbiotic culture of acetic acid bacteria (AAB) and yeast (SCOBY) in a base of sugared tea infusion at ambient temperature for 7-14 days. Regular consumption of Kombucha confers potential health benefits due to the presence of live cultures and high concentrations of bioactive components such as vitamins, polyphenols, and organic acids. However, industrial production of Kombucha faces challenges due to the limited information on the dynamic changes in its microbial community composition and the lack of knowledge regarding their health-promoting characteristics. The impact of fermentation conditions and added substrates on starter cultures, physicochemical characteristics and functional activities is also not well understood. Objectives: This study aimed to determine the microbiological characteristics of New Zealand Kombucha starter cultures and evaluate the probiotic potential of AAB and yeast isolated from commercial Kombucha products. The bioactive components, antioxidant activity, and antimicrobial activities of Kombucha fermented using a New Zealand starter culture under different fermentation conditions were also determined.--Shortened abstract
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    Assessment of process variables on the structural, material, and physical properties of acid milk gels : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Food Technology at Massey University, Palmerston North, New Zealand. EMBARGOED until 9 June 2026.
    (Massey University, 2023) Kim, Ji Uk
    The aim of this study was to investigate the effect of process and formulation variables on cream cheese microstructure, properties, and their interactions. A systematic approach toward assessing these effects was conducted with a model cream cheese that was developed as part of the study design. Preliminary analysis compared the structural and material properties of commercial cream cheeses against the model composition to determine the extent of formulation variations on the performance of the cream cheese. In terms of compositional variables, both the ratios of fat to moisture and protein to moisture were found to positively correlate with large deformation material properties cream cheeses. These ratios were accordingly fixed in the model cream cheese formulation used within the study. The impact of coagulation kinetics on the structural and material properties of the model cream cheese was then investigated. Milk coagulation was conducted using either glucono delta-lactone (GDL) or lactic acid starter. Acid milk gels formed using GDL showed faster pH decrease during the early stage of acidification, causing earlier gelation at higher gelation pH when compared to gels using culture as acidulant. Amongst other observations, it was seen that the application of GDL as acidulant produced greater acid gel firmness (i.e., storage modulus (G′)) and higher rigidity in the corresponding cream cheeses when compared to acid gels and cream cheeses prepared using starter cultures as the acidulant. The role of additional processing and formulation variables (homogenisation pressure, coagulation pH, coagulation temperature, and stabiliser level) on cream cheese physical, material, and microstructural properties was also determined. Protein-protein and protein-fat interactions were hypothesised as the primary structural contributors to the physical properties of cream cheese, and thus variables that impacted on these interactions were considered as most actively influencing cream cheese properties. Findings were able to show that cream cheese microstructure and its associated properties demonstrated well-defined correlations to specific and controllable processing elements within the manufacturing process, showing significance in interactions between parameters in multivariable linear regression analysis (P < 0.05). Finally, the role of mineral balance of the properties of creams cheese was investigated. Here, different concentrations of the calcium chelating agent, ethylenediaminetetraacetic acid (EDTA), were added to the milk prior to coagulation. Progressive addition of EDTA was seen to reduce levels of insoluble calcium, which in turn led to weakened structural and material properties of both acid milk gels and corresponding cream cheeses. Findings here indicated the particular contribution of ionic content and equilibrium on cream cheese properties during manufacture.
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    Commercial and public health applications of DNA monitoring : a thesis presented in partial fulfillment of requirements of the degree of Doctor of Philosophy in Microbiology and Genetics at Massey University, Palmerston North, New Zealand. EMBARGOED indefinitely.
    (Massey University, 2015) Sugrim, Kenneth
    This thesis reports analyses and findings from microbiology and metagenomic assessments of microorganisms at a beverage processing plant in Fiji. It includes metagenomics analyses from rivers and soils in Western Viti Levu. Chapter 1 provides a general overview of microbiological issues associated with product quality in beverage plants. It outlines regulatory expectations and accepted protocols for product quality assurance. It then introduces methods of comprehensive microbial assessments based on DNA sequencing technologies, some of which were applied in the present study. Chapter 2 addresses the issue of biofilms at the plant, asks and answers the question of whether existing Clean in Place (CIP) protocols are necessary and sufficient to ensure product quality. It was shown that ozonation is a redundant component of the current CIP protocols. Furthermore, it was established that CIPs could be extended from 24 hour intervals to 36 hour intervals without compromising product quality. These findings have led to procedural changes at the plant. This refinement has been estimated to annually save the plant US $11 million. Chapter 3 provides a comprehensive assessment of microorganisms at the plant (storage tanks, buffer tanks and boreholes) and in rivers and tributaries within a 10 km radius of the plant. Whole genome shotgun sequences showed that microbial compositions were similar in the rivers and boreholes. Although water bottled at the plant is drawn from an aquifer, the similarity of microbial compositions suggests that management of water quality at the plant needs to consider surrounding rivers that may affect aquifer water quality. Chapter 4 examines the microbial composition of soils within and outside the plant (farmlands). The microbial composition was found to be similar in these two zones. This suggests that environmental management plans also need to consider the close relationship between land-based activities within and surrounding the plant (farmlands). In both Chapter 3 and 4 a small proportion of reads were reported from organisms that have the potential to impact water quality. This included organisms with pathogenic potential and also organisms whose properties could affect the aesthetic quality of the beverage. Thus, this raises the need for their continuous monitoring and control. Chapter 5 compares two methods of comprehensive assessment (Whole Genome Shotgun Sequencing WGSS and 16S rDNA sequencing) with the Illumina sequencing platform. It was shown that WGSS sequence analysis provided up to 100 orders of magnitude more taxonomic resolution than 16S rDNA. 16S rDNA was nevertheless shown to be useful for drawing conclusions regarding composition differences with some samples. Thus, given its relative low cost in comparison to WGSS, 16S rDNA sequencing is likely to be a useful tool for some applications and questions in environmental microbiology. Chapter 6 reports a bioinformatic approach to characterise bacteria recovered from the beverage product at the plant. The genomes of these isolates contained pathogenicity, virulence and antibiotic resistance loci, raising the issue of the need for their possible future monitoring at the plant. One advantage of the bioinformatics approach adopted for characterisation of bacteria over characterisation using biochemical tests is that the sequence data obtained provide a means to now develop DNA amplification primers to be used in future monitoring. Chapter 7 describes loop mediated amplification (LAMP), and the possibility of using this isothermal DNA amplification approach for future monitoring at the plant. This method could be used to specifically target microorganisms of potential concern identified in comprehensive assessments, such as undertaken for the current project. LAMP methodology is currently seeing widespread uptake in clinical health, environmental monitoring and food safety sectors because of its low cost, robustness and quantitative nature.