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Item Insights into wheat grain microstructure and composition for the development of novel flour with slow digestion properties and enhanced functional characteristics : 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(Massey University, 2025) AbhilashaWheat has been consumed as whole grains, broken grains, flattened format, and puffed format other than the flour format, which has a wide application in different types of food preparations. Wheat flour possesses a unique ability to form a cohesive dough that has viscoelastic properties. A range of products with wheat as their major ingredient are high glycaemic index (GI) foods as wheat flour contains highly digestible starch. However, the consumption of high GI foods is associated with chronic diseases such as diabetes, coronary heart disease, and obesity due to a rapid increase in blood glucose levels and secretion of insulin. The major objective of the research studies of this thesis included creating slowly digestible flour with improved functionality using slowly digested starch sources and non-starch components. Modifying wheat grain through different processing techniques alters the microstructure, and therefore, starch digestibility is impacted. Microstructure modification through various processing techniques, which can control the access of digestive enzymes to starch, could help develop products with controlled starch digestibility. To advance the understanding of the impact of wheat grain microstructure on starch hydrolysis, Chapter 3 explored a study on whole wheat grain in different commercially available forms (kibbled, cut grains, and flour) to understand the influence of microstructural changes on in vitro starch digestibility. The process of size reduction from raw intact grains to kibbled grains and flour caused an increase in overall starch hydrolysis (%) during simulated digestion in the order of flour>kibbled>cut>intact whole wheat grains. Cooking of these formats further increased their starch hydrolysis. However, both cooked cut and intact grains were low glycaemic with the expected glycaemic indices (eGI) of values of 54.08±0.03 and 41.98±0.04, respectively, revealing the role of intact microstructure in starch hydrolysis of wheat grains. Based on the role of intact microstructure, Chapter 4 investigated the possibility of reducing the starch hydrolysis in wheat grain formats (whole, flakes, and flour) by hydrothermal treatment and low-temperature storage of whole wheat grains. The extent of starch hydrolysis after oral-gastro-small intestinal digestion in vitro was significantly lower (p<0.05) in intact grains, flakes, and flours from the cold-stored grains than their non-cold-stored counterparts. In this study, scanning electron micrographs, pasting properties, water retention capacities, and relative crystallinity of the resulting flours revealed an enhanced degree of gelatinisation with the treatment temperature; however, cold-storage of treated grains resulted in a change in these properties due to the retrogradation of the starch. This study indicates that hydrothermal pre-treatment of grains followed by low-temperature storage for prolonged periods might help to reduce the starch digestibility of wheat grains and their resulting products and could be an effective strategy in developing reduced glycaemic impact grain products. However, in our preliminary trials, the flours from hydrothermally treated and low-temperature stored grains resulted in doughs of inferior viscoelastic properties. Furthermore, intending to create slowly digestible flour, Chapter 5 employed two approaches to modify a resistant starch: one involving soluble extracts from wheat flour and vital gluten (water solubles, salt-assisted water-solubles, and acid-solubles) and the other utilising hydrocolloids (guar gum, xanthan gum, locust bean gum, and carboxymethyl cellulose). Modifications from both approaches resulted in modified starch morphology with the formation of starch clusters mimicking the wheat flour. Moreover, the modification with hydrocolloids resulted in an improved pasting profile. Furthermore, in vitro digestion studies revealed that the starch hydrolysis rate was decreased for most of the cooked modified starches with wheat solubles and a slower starch hydrolysis profile until 60 min of simulated small intestinal digestion for most of the hydrocolloids used, carboxymethyl cellulose being the least effective in slowing the starch hydrolysis rate. Additionally, Chapter 6 evaluates the functionality and starch digestibility of a wheat flour system (dough and flatbread-chapatti) by utilising the modified starches created in Chapter 5 as low glycaemic ingredients. The interaction of the modified starches with vital gluten and wheat flour components resulted in improved viscosity of the functional flour. The microstructure of the functional flour dough indicated that the modified starches with wheat solubles (soluble extracts from wheat flour and vital gluten) and hydrocolloids improved the starch-protein matrix and gluten network. Furthermore, the in vitro digestion study revealed the overall starch hydrolysis of chapattis from all the functional flour formulations was significantly lower than the wheat flour chapatti. In conclusion, structural modifications of wheat grain could help reduce the overall starch hydrolysis of wheat grain products. Moreover, the wheat grain components have the potential to modify resistant starch sources to improve their functionality while retaining their slow digestion property. Also, utilising hydrocolloids to modify resistant starch sources could be an effective strategy to enhance the functionality of resistant starches in wheat-based systems. Modified resistant starches created using wheat solubles (soluble extracts from wheat flour and vital gluten) and hydrocolloids have potential applications with slow digestibility and improved functionality in wheat-based products.Item 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, BoyingBackground: 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 abstractItem Investigating the impact of tobacco particulate matter and selected components on monoamine oxidase activity, protein expression, and gene expression in brain SH-SY5Y cells : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Health Sciences at Massey University, Wellington, New Zealand(Massey University, 2023) Niraula, PrakshitSmoking addiction is one of the most widely discussed topics today due to a large number of smokers and the millions of lives it claims every year. Though a large population makes effort to quit smoking, the quit attempts mostly end in relapse, indicating the complex nature of smoking addiction. Nicotine is believed to be the major component responsible for the addiction, however, nicotine replacement therapy (NRT) has not proved to be a completely satisfying approach to smoking cessation. The low efficacy of NRT, as well as much research related to smoking addiction, suggest the role of non-nicotinic components in smoking addiction. It is hypothesised that monoamine oxidase inhibitors (MAOIs) present in tobacco smoke play a role in smoking addiction by prolonging nicotine’s reinforcing effect. Based on this hypothesis, Tobacco Research Group, Wellington has identified six candidate MAOIs in cigarette smoke. This PhD project aims to investigate the effect of nicotine, tobacco particulate matter (TPM) and the candidate MAOIs on MAO activity, MAO protein levels, MAO genes expression and global gene expression. A human neuroblast SH-SY5Y cell line was exposed to different regimens, which included ethanol (control), nicotine, TPM and the cocktail of candidate MAOIs for a period of 1, 3, 5 and 7 days. A modified kynuramine assay was performed after SH-SY5Y cells were exposed to the different treatments to determine the effect of the exposure treatments on MAO activity and to identify the optimum period of exposure that would result in maximum MAO inhibition. Exposure for a period of 3 days was chosen as an optimum period of time for exposure and for expression and whole genome experiments. Similarly, a MTT assay was performed to determine if the exposure treatment had any cytotoxic effect. Change in MAO protein and MAO gene expression after exposure to the different treatments for the optimum period of time were then determined using Western blot and qPCR, respectively. Finally, the effect of exposure treatments for an optimum period of time on global gene expression was determined using RNA sequencing (RNAseq) technology. It was observed that nicotine did not have any significant MAO inhibitory effect compared to the control in any of the treatments examined. TPM and MAOIs caused significant inhibition of total MAO activity when exposed for 1 and 3 days. However, no significant inhibition was seen in the exposure for 5 and 7 days. Change in MAO A and MAO B gene and protein expression levels after the exposure treatment for 3 days was not observed. Nevertheless, several genes were found to have differential expression after exposure to the treatments for 3 days. Many of these differentially expressed genes were linked with diseases and conditions related to smoking and addiction. The results suggest that the candidate MAO inhibitors identified by the Tobacco Research Group, Wellington could be the primary contributors of the MAO inhibitory property observed in cigarette smoke. This data could also possibly answer the major question regarding the component responsible for MAO inhibition by cigarette smoke in smokers. Further research is required to fully elucidate and understand the mechanisms behind the MAO inhibition from the MAOIs, and a better understanding of these mechanisms may provide a framework for the development of novel smoking cessation therapies.Item Evaluation of formulation design on the physical and structural properties of commercial cream cheeses(John Wiley and Sons Ltd on behalf of Institute of Food, Science and Technology (IFSTTF)., 2022-10) Kim J; Watkinson P; Matia-Merino L; Smith JR; Golding MThis study investigated how the compositional properties and formulation design of commercial cream cheese products model cheese influenced physical and structural properties as compared to a model cheese composition. Of the seven products evaluated, three were block format (B), two were spreadable (S) and two were spreadable light (SL), with fat contents ranging from 13.7 to 35.7%. The majority of cream cheese products indicated the inclusion of starter culture, and all formulations contained one or more stabilisers. Protein/moisture (p/m) ratio, i.e. the effective protein concentration in the non-fat substance, was seen to most strongly correlate with material properties, with a positive slope for fracture stress (R2 = 0.808) and modulus of deformability (R2 = 0.721). In terms of outliers, the datapoint for SL2 on this modulus versus p/m graph was lower than its regression line, and one rationale is that lower fat content (13.7%) gave a lower modulus from the milkfat component at 10°C test temperature. B1, with the highest p/m of 0.17, had a more dense distribution of larger fat globules coated with proteins than B2 and B3. Fracture stress and modulus of deformability were noted to be higher for full-fat than for lower fat cheese. In all products, elastic characteristics dominated viscous flow as expected. Findings have demonstrated that significant variance exists across the material properties of commerical cream cheeses, and which shows specific dependencies on their formulation.Item Biochemical characterisation of six novel monoamine oxidase inhibitors identified in tobacco smoke : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Health Sciences at Massey University, Wellington, New Zealand(Massey University, 2023) Hong, Sa WeonBackground: Tobacco smoking is supposed to be the most difficult addiction to give up, and nicotine has been observed as the main addictive agent found in tobacco smoke. However, research is showing that nicotine alone does not account for tobacco dependence. One hypothesis is that monoamine oxidase (MAO) inhibition from non-nicotine compounds in tobacco smoke contributes to nicotine addiction. Six new MAO inhibitors in tobacco smoke have been identified before this PhD project. Overall research aim: The overall research aim for this project was to characterize these six novel monoamine oxidase (MAO) inhibitors identified in tobacco smoke and study their interaction with MAO A and B enzymes. Methods: First, non-nicotinic components of tobacco smoke were tested for MAO inhibitory activity, using the kynuramine assay and recombinant human MAO enzymes. Next, a centrifugation-ultrafiltration method and a time-dependent assay were used as the primary tests of reversibility of the phenolic compounds. Then, Lineweaver-Burke (LB) plots were prepared to understand the kinetics and mechanism of inhibition of recombinant human MAO enzymes by the polyunsaturated fatty acids (PUFAs). Finally, molecular docking and in silico studies using SwissADME and PreADMET web tools were performed. Results: Catechols and hydroquinone showed potent irreversible MAO A inhibition. Among these, 4-methylcatechol displayed the highest activity for MAO A with an IC₅₀ value of 0.267 μM after 1h preincubation. Two PUFAs, α-linolenic acid and linoleic acid displayed potent inhibitory effect for MAO A with IC₅₀ values of 15.74 and 23.8 μM, respectively. Kinetic analysis revealed that α-linolenic acid and linoleic acid are competitive inhibitors of MAO A and MAO B. Molecular docking studies suggest that ternary complexes [MAO B-linoleic acid₂ species (EII)] may be formed. Conclusions: This PhD project showed that six novel MAOIs in tobacco smoke inhibited human MAO A and MAO B isoenzymes. The catechols and hydroquinone are irreversible MAO inhibitors, suggesting they may play a role in contribution to the addictive effects of nicotine and the low incidence of Parkinson’s disease in smokers. In addition, α-linolenic acid and linoleic acid are found to be reversible MAO inhibitors, suggesting these PUFAs may play a role in the lower MAO levels or activity in smokers. Overall, these findings suggest that MAO inhibitors from tobacco smoke may have pharmaceutical possibilities, perhaps in smoking cessation, or in relief of anxiety or depression or in Parkinson's and Alzheimer disease.Item Antioxidant and antimicrobial properties of by-products (peels and seeds) from 'Hass' avocado (Persea americana Mill.) : 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 6 May 2028.(Massey University, 2023) Shi, DanxiaBackground: ‘Hass’ avocado (Persea americana Mill.) is the most common variety of avocado grown for the global market. Avocado is rich in fibre; vitamins C, B, and E, unsaturated fatty acids (oleic, linoleic, linolenic acids); potassium; and other nutrients. Avocado oil production discards a large amount of by-product, which could be a potential source of bioactive molecules. Avocado peel and seed are rich in vitamins, fatty acids, proteins, and other bioactive substances. The main phytochemicals found in avocado seed and peel are procyanidins, flavanols, catechins, hydroxybenzoic acids, and hydroxycinnamic acids. Extracts of avocado by-product have antioxidant, antimicrobial, antimutagenic, cancer-preventing, and anti-cariogenic properties. Objective: There is a lack of New Zealand (NZ) research on the chemical composition and biological activity of ‘Hass’ avocado seed and peel. The utilization of avocado by-products (peel and seed) could provide a potential value-added resource for the NZ avocado industry. This thesis aimed to investigate the bioactive components, antioxidant activity, and antibacterial activities of NZ ‘Hass’ avocado seed and peel extracts. Methods: In this thesis, the total polyphenol content (TPC) was measured by the Folin−Ciocalteu assay, the tannin content (TTC) was measured with a microplate assay kit, and the procyanidin content (PC) was measured by the HCl-n-butanol assay. High-performance liquid chromatography–mass spectrometry was used for characterizing and quantifying the procyanidin B2 content of NZ ‘Hass’ avocado by-products. The in-vitro antioxidant activity of ‘Hass’ avocado by-products (peel and seed) was evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2’-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) assays. A 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay was developed for characterizing the in vitro antibacterial activity of NZ ‘Hass’ avocado by-products. In addition, thin-layer chromatography was combined with direct microbiological detection to show the areas of antibacterial activity from the separated compounds of hexane extracts of NZ ‘Hass’ avocado by-products. Mass spectrometry analysis was used to characterize the target components from hexane extracts of avocado peel and seed. The main antibacterial compounds (Fragment Ion Search score > 80 or match score > 80) have been tentatively identified by Compound Discoverer 3.3. Results: In this study of NZ ‘Hass’ avocado by-products, the ripe seed extract showed the highest TPC (64.55 ± 2.26 mg GAE/g) than the extracts of ripe peel, mature unripe seed, and mature unripe peel. After flash chromatography separation, the low-polarity fraction of the ripe peel had the highest DPPH and ABTS scavenging capacities (90 ± 0.08%; 93 ± 0.05%) compared with other extracts. In addition, the phytochemical content, in vitro antioxidant activity, and antibacterial activity were compared among NZ, Chinese, and Chilean ‘Hass’ avocado by-products. The extract from ripe seeds of NZ avocado had a higher TPC (52.82 ± 0.04 mg GAE/g) than the corresponding extracts from Chinese and Chilean avocados. The TTC and PC values showed non-significant differences (p > 0.05) among extracts from Chinese, Chilean, and NZ ‘Hass’ avocado by-products. Chilean ripe avocado seed extracts had the greatest inhibition of Staphylococcus aureus (98.21% ± 0.98) of all the extracts. Chilean ripe avocado seed extracts had the highest DPPH and ABTS scavenging capacities (90.94 ± 0.94 % and 92.83 ± 0.62 %, respectively). Moreover, (15Z)-9,12,13-trihydroxy-15-octadecenoic acid, (±)9-HpODE, and NP-011548 are three antibacterial fatty acids tentatively identified from hexane extracts of avocado peel, and (2E,4E,6E)-12-hydroxy-2,4,6-heptadecatrienoic acid, pentadecanoic acid, ascorbyl oleate, and ascorbyl stearate are the antibacterial fatty acids found in hexane extracts of avocado seed. Conclusion: NZ ‘Hass’ avocado seed and peel contain several valuable phytochemical components (polyphenols, tannins, procyanidins, and fatty acids). Moreover, they showed good antioxidant and antibacterial activities. The peel and seed from NZ ‘Hass’ avocado could be considered as a natural antibacterial and antioxidant in developing food additives in the future.Item Characterisation and protein complexation of an anthocyanin-bound pectin extracted from New Zealand blackcurrant (Ribes nigrum) : a thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Food Technology at Massey University, Palmerston North, New Zealand(Massey University, 2022) Salleh, NurhazwaniThe main objective of this thesis was to investigate the cause of physical instability in blackcurrant juice-milk system. Poor phase stability in fruit juice-milk beverages is a major challenge for the clean-label beverage industry as milk protein can interact with fruit components, like polysaccharides and polyphenols, generating unwanted characteristics such as coagulation of milk proteins and phase separation. Hence, the principal step to understand the causes of poor phase stability was to identify and study the key interactive components of the juice, which was extracted from the New Zealand blackcurrant (Ribes nigrum), and then investigate their interactions with milk proteins. The key components of the blackcurrant juice were first isolated using mild extraction procedures, via ethanol precipitation and dialysis, and were identified as a complex fraction particularly rich in pectin and anthocyanins (Chapter 4). Proximate analysis revealed that the fraction contained carbohydrate (78% w/w), uronic acid (21% w/w), protein (4.8% w/w), anthocyanin (3.9% w/w) and calcium (2.2% w/w). The pectin-rich fraction had a net negative surface charge of -23.1 mV (at pH 4.8), a pKₐ value of 1.7 and a relatively high degree of esterification (65.2%). Constituent sugar analysis showed that the fraction was mostly made of galacturonic acid, rhamnose, arabinose and galactose, and NMR spectroscopic analysis revealed that it was rich in rhamnogalacturonans with arabinogalactan side chains. This pectic fraction was unique as it was highly pigmented, with cyanidin 3-O-rutinoside as its major anthocyanin. Liquid chromatography revealed that the anthocyanins were tightly bound to the fraction as methanol used in the technique failed to separate them. Results from size-exclusion chromatography coupled with multi-angle laser light scattering showed that the blackcurrant juice contained two major pectic fractions—≈283 kDa present at 14.6% w/w and ≈97 kDa at 85.5% w/w—with the latter producing higher UV₂₈₀ ₙₘ signal, signifying that proteins and/or polyphenols were present mainly in the second fraction. Association of anthocyanins to biopolymers like pectin and protein can occur via multiple interactive forces (electrostatic, hydrophobic and hydrogen bonding forces), and pH is known to play a significant role as it can affect the associative mechanisms of anthocyanins by changing their molecular configuration and ability to electrostatically interact. An attempt to dissociate blackcurrant anthocyanins from the blackcurrant biopolymers was carried out by disrupting electrostatic interactions and changing the planarity of anthocyanins via pH adjustments and ultra-filtration (Chapter 5). Lowering the juice pH to 2 did not result in anthocyanins dissociation, likely because anthocyanins were bound to the biopolymers by other interactive forces apart from the electrostatic bonds. Increasing the juice pH to 4.5 might have dissociated some anthocyanins from the biopolymers, but this was not reflected in the analysis of anthocyanins, probably because the freed anthocyanins had degraded before the analysis was carried out. Overall, size segregation of the juice components via ultra-filtration was relatively effective. Regardless of the pH, majority of the anthocyanins were still tightly associated with the large molecular weight biopolymers, confirming the involvement of multiple interactive forces. In order to uncover the cause of phase instability in blackcurrant juice-milk system, a complexation study between the isolated pectin-rich fraction and whey proteins was conducted (Chapter 6). The impact of bound anthocyanins on pectin-protein interactions was studied by exploring the effects of pH (pH 3.5 and pH 4.5), heating (85 °C, 15 min) and heating sequence (mixed-heated or heated-mixed). The pH was found to influence the colour, turbidity, particle size and surface charge of the mixtures, but its impact was most drastic when heating was introduced. Heating increased the amount of blackcurrant pectin within the complexes—especially at pH 3.5, where 88% w/w of the initial pectin was found in the sedimented (insoluble) fraction. Based on physical stability measurements, the mixed-heated system at pH 4.5 displayed better stability than at pH 3.5. A noteworthy finding was that heating sequence was found to be effective in preventing the destabilisation of the systems. Mixing of components before heating produced a more stable system with small complexes (<300 nm) and relatively low polydispersity. However, heating whey proteins before mixing with blackcurrant pectin prompted protein aggregation, producing large complexes (>400 nm) that worsened the destabilisation. The influence of bound anthocyanins on pectin-protein complexation was further studied by comparing two types of pectin-protein mixtures: (i) a mixture that is rich in anthocyanin (blackcurrant pectin-whey protein, BCP-WP) and (ii) a mixture that is free of anthocyanin (citrus pectin-whey protein, CP-WP) (Chapter 7). The mixtures were prepared at pH 4.5 with and without heat treatment at 85 °C. The study revealed that there was no direct relationship between anthocyanin presence and the destabilisation of mixtures. The Fourier-Transform Infrared (FTIR) spectrum of the heated and non-heated BCP-WP sedimented fractions showed the emergence of a peak at 800-1200 cm⁻¹, signifying the presence of anthocyanin-protein interactions. This peak, however, was absent in the spectrum of any of the anthocyanin-free CP-WP sedimented fractions, indicating that the bound anthocyanins of blackcurrant pectin provided the whey proteins with additional binding sites. The findings from FTIR analyses also indicated that non-electrostatic forces were most likely the governing forces of the heated BCP-WP mixture, via hydrophobic interactions and later reinforced by hydrogen bonds upon cooling. This thesis revealed that poor phase stability of the blackcurrant juice-milk system should not be attributed exclusively to the blackcurrant juice components, particularly the polyphenols. Environmental factors like pH and heat were likely the leading cause of phase instability as they could intensify the interactions that occurred in the mixed system, which eventually destabilised the mixture. This suggests that appropriate processing conditions can be applied to positively affect the blackcurrant juice-milk system.Item Nutrition related health of female recruits in the New Zealand Army : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Nutritional Science at Massey University, Albany, New Zealand(Massey University, 2023) Martin, NicolaBackground: Basic training for military recruits is a physically demanding course that is generally a sudden change from an individual’s habitual lifestyle. Female recruits have physiological disadvantages in comparison to males, which contribute to lower aerobic fitness and higher risk of musculoskeletal injuries. Nutrition related health, including iron and vitamin D status, dietary intake and body composition is essential to support the health and physical fitness of female recruits. However, little is known about how these nutrition related health factors change during completion of basic training, their determinants or associations with measures of physical fitness in female recruits in the New Zealand Army. Objectives: The objectives of this research in females undertaking 16-weeks of basic training in the New Zealand Army were to 1) characterise iron status in female recruits during basic training and investigate associations with physical fitness; 2) investigate associations between iron stores, dietary patterns and non-dietary determinants of iron stores in female recruits at the commencement of basic training; 3) characterise vitamin D status in female recruits during basic training and investigate potential determinants at the commencement of basic training; and 4) characterise body composition, physical fitness and dietary intake during basic training and investigate associations between these three factors in female recruits. Methods: Data were collected at weeks 1 and 16 of basic training from female recruits who enlisted in the New Zealand Army between February 2014 and March 2016. Demographic, lifestyle and medical history information were self-reported via an online questionnaire at week 1. Dietary intake data from a food frequency questionnaire (FFQ) administered online and body composition measurements were collected at weeks 1 and 16. Body composition was determined by the InBody230 bioelectrical impedance analyser and included body mass (BM), skeletal muscle mass, fat mass (FM), fat free mass (FFM), total body water and percent body fat (%BF). Height and body mass index (BMI) were also determined. Biochemical data were assessed at weeks 1 and 16 and included serum ferritin (SF), transferrin saturation (TS), soluble transferrin receptor (sTfR), erythrocyte distribution width (RDW), haemoglobin (Hb) and serum 25-hydroxyvitamin D (25(OH)D). A 2.4km run, push-ups and curl-ups were performed at weeks 1 and 8 to assess physical fitness. Changes during basic training in iron status, 25(OH)D, body composition, physical fitness and dietary intake were investigated using paired t-tests. To explore dietary determinants of iron stores at the commencement of basic training, dietary patterns (DPs) from the FFQ were identified using factor analysis. The DPs were then examined alongside potential non-dietary determinants of iron stores. Following univariate analysis, age, %BF, previous blood donation, ≥6-hours of exercise per week and a vegetarian DP were analysed using a multiple linear regression model. To explore vitamin D status, changes in 25(OH)D were characterised by ethnicity and season. Following univariate analysis, age, BMI, ethnicity, season, exercise and SF were analysed as potential determinants of 25(OH)D at the commencement of basic training using a hierarchical linear regression model. Associations between physical fitness and iron status indicators and %BF were investigated using Pearson’s correlation coefficients. Associations between frequency intake of food categories and %BF were explored using the rho-Spearman’s correlation. Results: Of the 108 female recruits invited to take part in this research, 106 volunteered to participate. During basic training, the mean ± standard deviation (SD) changes for iron status indicators were that SF decreased (56.6 ± 33.7 to 38.4 ± 23.8μg/L, P<0.001), TS decreased (38.8 ± 13.9 to 34.4 ± 11.5%, P=0.014), sTfR increased (1.21 ± 0.27 to 1.39 ± 0.35mg/L, P<0.001), RDW increased (12.8 ± 0.6 to 13.2 ± 0.7%, P<0.001) and Hb increased (140.6 ± 7.5 to 142.9 ± 7.9g/L, P=0·009). At week 16, sTfR was positively associated (r=0.29, P=0.012) and TS was negatively associated (r=–0.32, P=0.005) with the week 8 run time. There were no significant associations between iron status and push-ups or curl-ups. Serum ferritin was positively associated with %BF (P<0.009) and negatively associated with blood donation in the past year (P<0.011), explaining 17.5% of the variance in SF. There was no association between SF and DPs in the multiple linear regression model. From week 1 to week 16, the mean ± SD for 25(OH)D was 102.5 ± 33.6 to 67.4 ± 22.6nmol/L (P<0.001) for basic training commenced in summer and 67.4 ± 21.5 to 73.8 ± 18.9nmol/L (P=0.033) for basic training commenced in winter. Overall, more than two-thirds of participants had suboptimal vitamin D status (<75nmol/L) at the end of basic training, regardless of the season training commenced. Increasing age and BMI, being of Pacific or Māori ethnicity and commencing basic training in winter were negatively associated with 25(OH)D. Collectively these determinants explained 45.0% of the variance in 25(OH)D at the commencement of basic training. From week 1 to week 16, the mean ± SD change for FM was -3.8 ± 3.6kg, %BF was -5.5 ± 3.7% and FFM was 3.8 ± 1.8kg (all P<0.001). There was no change in BM or BMI. All measures of physical fitness improved during basic training (P<0.001). There was a significant increase in frequency intake of protein, grains, fats, discretionary items and beverages (all P<0.001). A higher %BF at week 1 was positively associated with the 2.4km run time and negatively associated with push-ups at both weeks 1 and 8 (all P<0.05). Conclusions: Overall, 16-weeks of basic training in the New Zealand Army provides adequate nutrition to support training-induced adaptations in physical fitness and body composition of most female recruits. Optimal %BF and FFM were associated with improved physical fitness, while BMI is an unreliable measure of body composition in this physically active cohort. However, storage and functional iron parameters indicated a decline in iron status and 25(OH)D indicated a decline in vitamin D status in female recruits during basic training. Diminished tissue iron status was associated with impaired aerobic fitness. A lower %BF and blood donation in the past year were the strongest determinants of reduced iron stores while wintertime and being of Pacific or Māori ethnicity were the strongest determinants of reduced 25(OH)D at the commencement of basic training. Therefore, while positive changes in nutrition related health are occurring during basic training, several factors are negatively impacting the iron and vitamin D status of female recruits, both before and during basic training. These factors are limiting the potential of female recruits to achieve optimal health and physical fitness. Delivering education, clinical screening and early supplementation of iron and vitamin D are recommended strategies to counter suboptimal iron and vitamin D status and enhance the success of female recruits during basic training in the New Zealand Army.Item The role of microorganisms in shaping the nectar chemistry of mānuka plants (Leptospermum scoparium) : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Ecology at Massey University, Manawatū, New Zealand(Massey University, 2022) Bresciano Kauffman, Jorge CarloMānuka (Leptospermum scoparium) honey is one of the main export products from New Zealand. The distinctiveness of this honey comes from the floral nectar, which possesses dihydroxyacetone, a carbohydrate with UV protection capabilities, which converts to methylglyoxal, usually during the honey maturation process. Methylglyoxal gives mānuka honey its biological activity (antimicrobial and antioxidant properties) and is often used as a quality marker. While it is acknowledged that microorganisms play an important role in plant ecology, their abundance and impact on nectar chemistry remain understudied. Microorganisms can arrive in the nectar by pollinator activity or through the phloem and can change nectar chemical properties. This thesis aims to fill a gap in the knowledge of the microbial diversity of the nectar; the impact of pollinators in the microbial nectar community, and the effect of bacteria on dihydroxyacetone production and sugar content in mānuka nectar. To achieve this aim, a combination of metagenomics, bacterial cultivation, chemical analyses, and biological in vivo and in vitro assays was conducted. The results show that mānuka nectar bacterial communities were dominated by Pseudomonadales, followed by Rhizobiales, Sphingomonadales, Corynebacteriales, Baccillales, Enterobacteriales, Xanthomonadales, Clostridiales, and Lactobacillales, while nectar fungi communities were dominated by Microbotryomycetes, Dothideomycetes, Malasseziomycetes, Sordariomycetes, and Ustilaginomycetes. When comparing bagged (pollinator restricted) and unbagged (with pollinator access) flowers, a bioinformatic and statistical analysis showed the bacterial community did not differ in community composition. In contrast, the fungal community was affected by pollinator visitation, and by plant genotype. The inoculation of an important functional bacterial Pantoea agglomerans, that previously was identified as a biomarker for the bacterial community, determined by linear discriminant analysis and network analysis, showed a significant increase in DHA using natural nectar under the laboratory. However, P. agglomerans in vivo inoculation did not change the composition of the main nectar sugars, suggesting that bacterial inoculation can maximize important plant metabolites like DHA, with minor disruption to nectar sugar content. The cultivable bacterial community differed little from the main groups found through metabarcoding, meaning the stability or structure of a core bacterial community in the nectar can be maintained through cultivation. This thesis fills an important gap in the knowledge of microbial ecology of mānuka plants and provides insights into how to manipulate key bacteria to increase DHA nectar content.Item Peptide fingerprinting and predictive modelling of fermented milk : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Food Technology at Massey University, Palmerston North Campus, New Zealand(Massey University, 2021) Murphy, FionnualaFermented milk products are valued by consumers and the food industry for their nutritional properties, pleasant taste, and texture. Consumer demands and expectations for such products are constantly changing. Understanding how consumers perceive the sensory characteristics of food and the relationship these characteristics have with the chemical components of food can provide insight that can enable food researchers and manufacturers to develop food products that are tailored to provide enhanced sensory qualities. Establishing techniques that allow for in-silico prediction or correlation of sensory qualities can enable a more rapid approach that would aim to enable researchers to meet the demands of consumers. This research firstly explored mass spectrometric techniques for the rapid fingerprinting of milk and fermented milk products, using Matrix-Assisted Laser Desorption Ionisation - Time-of-Flight Mass Spectrometry (MALDI-TOF MS) and Rapid Evaporative Ionisation Mass Spectrometry (REIMS), two technologies that require minimal sample preparation and can rapidly generate a fingerprint of a food’s chemical components. Peptide fingerprints obtained by MALDI-TOF MS and analysed by principal component analysis were effective at discriminating the two fermented milk and milk samples. Supervised discrimination of low molecular weight fingerprints obtained via REIMS and MALDI-TOF MS proved less effective but demonstrated some potential and could be used alongside other analyses in future studies. These techniques were explored with a view to establishing a technique that could provide rapid insights into a food’s chemical composition, and which could also effectively discriminate the chemical components of the product. Such techniques could be used for rapid screening of products and can provide insight into the chemical components that are driving the variation in different products, which may be reflective of the differences in sensory characteristics. Next, peptide fingerprinting and predictive modelling were investigated in milk fermented with various bacterial combinations, including probiotic cultures. Fingerprinting was performed on samples collected at each hour of fermentation. Predictive modelling techniques, using both regression and classification approaches, were trialled in order to predict the change in signal intensity throughout fermentation. This aimed to understand if peptides could be predicted throughout fermentation, with a view to enable the targeted prediction of desirable peptides, or other relevant components, which may impart favourable sensory qualities in the final product. Regression techniques were somewhat effective for predicting the signal intensity of individual m/z ions throughout fermentation. Most of the ions did not follow a linear relationship, and, as such, a multiple linear regression model was unable to model most of the ions. Using a generalised additive model, a non-linear approach, improved the performance in most cases and could predict the signal intensity of individual ions throughout fermentation. However, the model was unable to correctly predict all cases. Classification techniques were effective for predicting the general direction of the signal intensity between start and end fermentation times. Five classification techniques were trialled, with each model providing accurate predictions for the increase or decrease of signal intensity between early and late fermentation times. Lastly, consumer panellists were recruited to evaluate the change in important sensory characteristics throughout the fermentation of milk prepared using two different starter cultures. This aimed to understand if consumer responses to such products could be correlated with instrumental analysis, in order to predict the consumer responses from instrumental data. Consumers perceived significant differences in bitterness and flavour intensity between fermented milk samples at different fermentation time points. There were significant correlations between peptide fingerprints and the consumer rankings for the sensory attributes in each fermented milk product. XGBoost regression could predict consumer responses with reasonable accuracy. This thesis explored the fermentation of milk using specific bacteria and fermentation processes. To validate this work, further products could be explored, in addition to different processing parameters. Furthermore, a more in-depth analysis of the chemical components of the products could be investigated and analysed with additional sensory evaluation to further explore and confirm the findings.
