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Item A period of 10 weeks of increased protein consumption does not alter faecal microbiota or volatile metabolites in healthy older men: a randomised controlled trial(Cambridge University Press on behalf of The Nutrition Society, 2020-07-02) Mitchell SM; McKenzie EJ; Mitchell CJ; Milan AM; Zeng N; D'Souza RF; Ramzan F; Sharma P; Rettedal E; Knowles SO; Roy NC; Sjödin A; Wagner K-H; O'Sullivan JM; Cameron-Smith DDiet has a major influence on the composition and metabolic output of the gut microbiome. Higher-protein diets are often recommended for older consumers; however, the effect of high-protein diets on the gut microbiota and faecal volatile organic compounds (VOC) of elderly participants is unknown. The purpose of the study was to establish if the faecal microbiota composition and VOC in older men are different after a diet containing the recommended dietary intake (RDA) of protein compared with a diet containing twice the RDA (2RDA). Healthy males (74⋅2 (sd 3⋅6) years; n 28) were randomised to consume the RDA of protein (0⋅8 g protein/kg body weight per d) or 2RDA, for 10 weeks. Dietary protein was provided via whole foods rather than supplementation or fortification. The diets were matched for dietary fibre from fruit and vegetables. Faecal samples were collected pre- and post-intervention for microbiota profiling by 16S ribosomal RNA amplicon sequencing and VOC analysis by head space/solid-phase microextraction/GC-MS. After correcting for multiple comparisons, no significant differences in the abundance of faecal microbiota or VOC associated with protein fermentation were evident between the RDA and 2RDA diets. Therefore, in the present study, a twofold difference in dietary protein intake did not alter gut microbiota or VOC indicative of altered protein fermentation.Item Industrial multi-shot gin manufacture : a thesis presented in partial fulfilment of the requirements for the degree of Master of Engineering in Chemical and Bioprocess Engineering at Massey University, Manawatu, New Zealand(Massey University, 2022) Welch, Beau EvanThis study investigates whether a concentrated gin ‘hotshot’ could be developed to increase production efficiency and still output. This concentrated ‘hotshot’ would also decrease transport costs and be later diluted to final strength. This ‘hotshot’ must have the same characteristics as the original gin once diluted with water and ethanol but, after distillation should be far more concentrated in flavour compounds. Recent literature published at the end of this study call this technique multi-shot gin. Since this was found at the end of this project the title and aim were renamed from gin ‘hotshot’ to ‘multi-shot’ gin to match industry standard. There are many different gas chromatography (GC) methods to analyse the volatile organic compounds (VOC) present in gin samples. An analytical method was developed to analyse the VOC via gas chromatography – flame ionization detector (GC-FID) and gas chromatography – mass spectrometry (GC-MS). This method utilised both internal and external standardisation techniques to determine the concentration of the key analytes within the gin. Out of the tested solvents, chloroform, hexane, dichloromethane and dimethyl sulfoxide it was found that hexane produced the highest extraction yield for the key analytes of interest. The highest yield was found using 1 mL of hexane to 3 mL of gin sample and extracted by gently agitating for 17 hours. GC-MS analysis was performed to identify 28 total volatile organic compounds within the gin. The key compounds of interest were found to be α-pinene, β-myrcene, limonene, γ-terpinene, and citronellal and their concentration in the original gin specimen was found to be 116 ± 5 mg/L, 57 ± 3 mg/L, 18 ± 1 mg/L, 8 ± 1 mg/L and 23 ± 1 mg/L respectively. During gin manufacture the complex flavour extraction process can be broken down into several smaller micro-processes that were focused on in this study: maceration, macerate distillation, condensed vapour percolation and vapour infusion. Analyte extraction parameters were investigated and as the botanical ratio increased, the concentration of the analytes in the distillate increased but with gradually declining effectiveness for maceration and the condensed vapour percolation. Vapour infusion had not yet reached the threshold of declining returns. The results from the research conducted for this project show that a concentrated ‘hotshot’ is possible. Vapour infusion was found to be the most efficient extraction process and can be combined with macerate distillation for a hybrid method to maximise analyte extraction.Item Neuropsychological symptoms in workers handling cargo from shipping containers and export logs(Springer-Verlag GmbH, 2022-10) Hinz R; 't Mannetje A; Glass B; McLean D; Douwes JPURPOSE: Acute poisonings of workers handling shipping containers by fumigants and other harmful chemicals off-gassed from cargo have been reported but (sub)-chronic neuropsychological effects have not been well studied. METHODS: This cross-sectional study assessed, using standardised questionnaires, current (past 3-months) neuropsychological symptoms in 274 container handlers, 38 retail workers, 35 fumigators, and 18 log workers, all potentially exposed to fumigants and off-gassed chemicals, and a reference group of 206 construction workers. Prevalence odds ratios (OR), adjusted for age, ethnicity, smoking, alcohol consumption, education, personality traits and BMI, were calculated to assess associations with the total number of symptoms (≥ 3, ≥ 5 or ≥ 10) and specific symptom domains (neurological, psychosomatic, mood, memory/concentration, fatigue, and sleep). RESULTS: Compared to the reference group, exposed workers were more likely to report ≥ 10 symptoms, statistically significant only for retail workers (OR 6.8, 95% CI 1.9-24.3) who also reported more fatigue (OR 10.7, 95% CI 2.7-42.7). Container handlers with the highest exposure-duration were more likely to report ≥ 10 symptoms, both when compared with reference workers (OR 4.0, 95% CI 1.4-11.7) and with container handlers with shorter exposure duration (OR 7.5, 95% CI 1.7-32.8). The duration of container handling was particularly associated with symptoms in the memory/concentration domain, again both when compared to reference workers (OR 8.8, 95% CI 2.5-31.4) and workers with the lowest exposure-duration (OR 6.8, 95% CI 1.5-30.3). CONCLUSION: Container handlers may have an increased risk of neuropsychological symptoms, especially in the memory/concentration domain. Retail workers may also be at risk, but this requires confirmation in a larger study.Item Volatile organic compounds emitted by invasive and native plant species under invasion scenarios and their potential ecological roles : a thesis presented in partial fulfilment of the requirement for the degree of Doctor of Philosophy in Ecology at Massey University, Palmerston North, New Zealand(Massey University, 2020) Effah, EvansClimate change, human migration, and global trade favour the spread of plant species beyond their natural ranges. Many of these plants become invasive, posing a risk to the persistence and survival of native species and the ecosystems they invade. In New Zealand, the European woody shrub Calluna vulgaris (heather) is the most widespread invasive weed on the Central Plateau of North Island. Like most exotic invasive plants, the chemical behaviour (i.e. chemical production and chemical mediated interactions) of heather in its invaded habitat is poorly understood. Moreover, despite the struggles of native plants to endure the stress induced by exotic weeds, no study has documented the chemical behaviour of native plant species in plant invasion scenarios. Volatile organic compounds (VOCs) are secondary plant metabolites that play a vital role in plant communication with other organisms and are highly responsive to biotic and abiotic stress. Therefore, measuring VOC emissions during plant invasion could provide valuable information about plant responses to the changing environment and their potential impacts on other community members. This thesis aimed to investigate VOCs emitted by the invasive weed heather and a New Zealand native plant Leptospermum scoparium (mānuka) under field conditions, while determining the environmental factors regulating their emissions and exploring their potential ecological impacts under lab and field conditions. Results from the field trials on the Central North Plateau showed variations in the volatile profiles of heather and mānuka growing at different sites, with both plants emitting lower amounts of VOCs at sites where other exotic invasive plants were present. This reduction in VOC emissions was mostly due to indirect changes in environmental factors, like soil properties, which were driven by the invasive weeds heather and Cytisus scoparius (Scotch broom; henceforth broom). This thesis also documents the chemical responses of heather to two major stresses encountered in New Zealand; 1) elevated solar ultraviolet radiation (UV) and 2) damage caused by its introduced specialist herbivore and biocontrol agent Lochmaea suturalis (heather beetle). Results from these trials demonstrate that high UV radiation reduced the volatile emissions of some compounds (mainly terpenoids) and that the impacts of herbivory by heather beetle on VOC emission depended on the developmental stage of the herbivore, plant phenology, and season. The ability of VOCs emitted from heather and broom to affect the germination and growth of mānuka was also tested in the lab, while the impact on arthropod communities were investigated at sites on the Central North Plateau. The results suggest that VOCs produced by invasive plants may have phytotoxic effects toward mānuka and may alter arthropod community structure. This thesis highlights the complexity of plant chemical communication under invasion scenarios and invites further exploration of the interactions between exotic invasive plants and native species to broaden our understanding of invasion ecology to support weed management, biocontrol, and conservation efforts.Item Characterisation of volatile constituents of six native New Zealand ferns and changes in volatile emission in response to herbivore, mechanical wounding and phytohormone treatments : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Ecology at Massey University, Manawatū Campus, New Zealand(Massey University, 2018) Soriano, KeyleeEvolution has led to the development of countless defence strategies in terrestrial plants to deal with the threat of herbivory and disease. The production of specialised morphological structures, such as thorns and trichomes, is a prominent defence mechanism that directly deters potential herbivores. However, plants are capable of enlisting the aid of natural predators and parasites of attacking herbivores as a means of indirect defence, through the production and release of volatile organic compounds. This has prompted much research into the regulation and ecological roles of volatile organic compounds in many higher plant groups. However, similar studies are seldom in lower plants such as the Monilophytes thus we know very little concerning the ecological importance of plant emitted volatiles in this group. In this study, I investigated the volatile compounds released by six abundant native fern species using direct solvent extraction and headspace collections, and characterized the volatile emissions under natural herbivory, phytohormone treatment, and mechanically induced stress. Solvent extracts and headspace collections were analysed using gas chromatography coupled with mass spectrometry allowing the quantitative and qualitative description of the volatile profiles. These results were then used to relate volatile emission to the growth mode and other potential defence strategies of these species. A total of 15 volatile compounds were identified over the course of this thesis with links to fern physiology. Quantitative results revealed no differences in emissions under phytohormone treatment or artificially induced stress. The comparison of two methods, solvent extraction and headspace sampling, reveals the limitations the solvent extraction method has on elucidating fern-insect interactions. Research on fern volatiles could give insight into the evolution of anti-herbivore defence mechanisms in plants and the interactions between native ferns and arthropod communities. Potential applications of research in fern chemistry include pharmaceutical or perfumery uses and fern conservation, which should be incentives for further work. The results and conclusions made from this thesis does not only contribute to the limited pool of knowledge in this field of research but may also serve as a foundation for future studies.Item Enhancement of aroma volatile compounds in apples : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Plant Science at Massey University(Massey University, 1997) Wirut, Ampun; Ampun, WirutApple aroma is a complex of volatile compounds produced by fruit. It is one of the most important quality factors giving a characteristic flavour to fruit and its products. The present study investigated the effect of short-term hypoxic concentrations and duration of CO2 and/or N2 treatments at 20°C on changes in production of important aroma volatile compounds after treatment during shelf-life conditions at 20°C and 70% RH, in some commercial apple cultivars at harvest and following storage in air or controlled-atmospheres (CA). Different methods of extracting and analysing aroma volatiles from apples were compared in order to optimise a process for subsequent experiments. Juice from homogenised apple fruit could be held in an ice bath for up to 60 minutes after homogenisation without loss of major volatile compounds. Octyl acetate concentrations between 50 and 5000 ppm in the final concentrated sample was a suitable internal standard for GLC analysis; as an external standard, a mixture of authentic volatile compounds of known concentration provided accurate quantification of aroma volatiles from juice samples. Volatiles were obtained from apple juice either by a dynamic headspace (purge and trap) technique using a Tenax® trap or by direct extraction with a diethyl ether:n-pentane (2:1, v/v) mixture. The solvent extraction technique was simpler and faster than the purge and trap method, taking 5 seconds rather than 1 hour; it was also more efficient, resulting in 1.7 fold more total volatiles with better reproducibility. Application of hypoxic gas atmosphere to apples (100% CO2, 100% N2 or < 2.5% O2) demonstrated consistently enhanced headspace acetaldehyde, ethanol and ethyl acetate in 'Granny Smith', 'Braeburn' and 'Red Delicious' cultivars. A marked increased production of ethanol in response to hypoxic treatments was always followed by a several fold enhancement in both number and concentration of ethyl esters, including the aroma-impact volatiles ethyl butanoate, ethyl 2-methyl butanoate and ethyl hexanoate in juice from all cultivars. The increased concentration of these compounds was accompanied by decreased production of other esters requiring the same acyl group for their synthesis, such as propyl butanoate, butyl acetate and hexyl acetate, and some alcohols and aldehydes, including hexan-1-ol, 2/3-methyl butan-1-ol and trans-2-hexenal. These results confirmed the hypothesis of the competitive nature of the acyl esterifying system in apples. Exposing apples to 100% CO2 for 18 - 24 hours at 20°C achieved optimum enhancement; a longer time (48 hours) did not further increase important aroma-impact ethyl esters but caused a marked reduction in non-ethyl esters, while a shorter period of exposure (6 - 12 hours) had minimal effect. Apples previously stored (0°C) for 6 months or longer before exposure to hypoxic treatments did not have important volatile ethyl esters enhanced. Application of 1000 ppm ethylene for 24 hours did not increase volatile production in apples compared with non-treated fruit. Poststorage production of most aroma volatile compounds from 'Granny Smith' and 'Fuji' apples stored in a controlled-atmosphere (CA) of 2% CO2 + 2% O2 at 0.5°C was depressed after 10 - 14 weeks storage, although 2-methyl butan-1-ol was enhanced and there was no effect on trans-2-hexenal. Poststorage treatment with 100% CO2 (24 hours at 20°C) consistently and markedly enhanced headspace acetaldehyde, headspace ethanol, headspace ethyl acetate and aroma impact compounds, ethyl butanoate, ethyl 2-methyl butanoate and ethyl hexanoate in fruit from both refrigerated air (RA) and CA storage regimes. The hypoxic treatment had no effect on production of butan-1-ol and hexan-1-ol in CA, or hexanal in RA 'Granny Smith', propan-1-ol and butan-1-ol in either RA or CA, or hexanal and trans-2-hexenal in RA 'Fuji' apples. Hypoxic treatments reduced production of butyl and hexyl acetate in 'Fuji' apples, and 2-methyl butan-1-ol in both cultivars. The ability to sustain enhanced production of ethyl esters in CO2 treated RA or CA 'Granny Smith' or CA 'Fuji' apples decreased as time of storage progressed, probably due to shortage of acyl CoA substrates for volatile synthesis. CA retarded flesh softening and acid loss in both cultivars. Examination of volatile production from 6 commercial apple cultivars established that esters, alcohols and hydrocarbons accounted for 70% - 88% of the total number of volatiles found and compounds with straight chain and even numbered carbons predominated in the composition of esters and alcohols. Differences among apple cultivars were associated with number and concentration of volatile compounds produced. Treatment with 100% CO2 (24 hours at 20°C) consistently enhanced production of headspace volatiles in all cultivars. Production of aroma impact ethyl esters following hypoxic treatments consistently occurred with 'Red Delicious', 'Braeburn', 'Granny Smith' and 'Pacific Rose', with less of a response in 'Cox's Orange Pippin' and none in 'Royal Gala' apples. Non ethyl esters and alcohols, other than ethanol and propan-1-ol, were reduced after CO2 treatment in all cultivars, except for butan-1-ol in 'Cox's Orange Pippin' apples. Hexanal and trans-2-hexenal were either reduced or not affected following CO2 treatment, depending on cultivar. The magnitude of enhancement and the degree of reduction in production of aroma volatile compounds following hypoxic treatment varied among cultivars; the higher the magnitude of enhancement of ethyl acetate, the greater the degree of reduction in other acetate esters, supporting the concept of a competitive interaction in the acyl esterification in apples. Hypoxic treatments consistently caused profound increases in aroma volatiles in most apples cultivars studied. Such a treatment has potential to increase the strength and value of commercially important flavour fractions in apple juice and aqueous essence and enhance aroma in fresh apples.Item Enhancement of aroma and flavour volatiles in apple juice : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Plant Physiology at Massey University(Massey University, 1999) Dixon, JonathanAroma typical to apples develops during ripening and is comprised of a large range of volatile chemical compounds from several chemical classes. Previous research has established that exposing apples to hypoxic conditions induces changes in volatile concentrations; acetaldehyde and ethanol accumulate to high concentrations and after return to aerobic conditions ethyl esters increase and non-ethyl esters decrease. The present study investigated the effect of short term-hypoxic treatments on the enhancement of ethyl esters and decrease in non-ethyl esters with respect to: organoleptic changes in apple aroma induced by exposure to hypoxia; the influence of temperature and time at 0 °C before treatment on the magnitude of enhancement of ethyl esters after exposure to hypoxia; the effect of cultivars and ripeness stage on types and quantities of ethyl esters enhanced after exposure to hypoxia. Brief periods of hypoxia at ambient temperatures have potential for disinfestation treatments or as pre-treatments to maintain fruit quality during extended storage. Volatile compounds were extracted from 20 mL aliquots of apple juice with an equal volume of diethyl ether:n-pentane (2:1 v/v), vigorously stirred for 3-5 seconds, frozen at -18 °C to separate solvent and aqueous phases, concentrated with a fast stream of oxygen free nitrogen (200 mL min-1) to 200 μL and analysed by gas chromatography. Apple juice could be held in ice or air up to 256 minutes without loss of volatile compounds. Loss in solvent washes was 76.5% for octyl acetate and recoveries during concentration of the solvent extract ranged from 2.5% for ethyl acetate to 86.4% for trans-2-hexenal. Solvent extraction was simpler, faster, extracted more compounds, and had better reproducibility than dynamic headspace extracts obtained using Tenax® traps. Nine cultivars of apples, Cox's Orange Pippin, Fuji, Golden Delicious, Granny Smith, Pacific Rose, Red Delicious, Royal Gala, Splendour and Southern Snap were exposed to 100% carbon dioxide for 24 h at 20°C. Apples exposed to hypoxia had concentrations of acetaldehdye, ethanol, ethyl acetate and ethyl esters consistently enhanced while concentrations of acetate esters and aldehydes were depressed. Maximum ethyl ester enhancement occurs within 2 to 3 d after removal from hypoxia. Exposure to hypoxia for 24 h at 20 °C did not affect rates of softening or induce physiological damage. Cultivars varied considerably in response to hypoxic treatment with Cox's Orange Pippin and Golden Delicious having the least and Fuji and Red Delicious the greatest enhancement in ethyl esters. Fruit exposed to hypoxia had larger odour unit scores than control fruit suggesting that such changes in volatile concentration may affect the aroma and/or flavour. Fuji and Royal Gala apples were exposed to 100% CO2 for 24 h, at 10, 15, 20 or 25 °C and maintained at treatment temperature for up to 14 d. Carbon dioxide and ethylene production and firmness were proportional to temperature but were unaffected by exposure to hypoxia. Ethyl esters were enhanced at all temperatures at differential rates according to cultivar. Apples treated and maintained at 10 °C had the greatest overall enhancement of ethyl esters and the least decrease in other esters compared to apples at 15, 20 or 25 °C. This enhancement in volatiles persisted for up to 10 d after removal from hypoxia. Best maintenance of apple quality after treatment with hypoxia is at low temperatures suggesting that apples treated with hypoxia and maintained below 15 °C would have enhanced volatile concentration. Noncooled Fuji and Royal Gala apples at preclimacteric to postclimacteric ripeness stages were exposed to 100% CO2 for 24 h at 20 °C for up to 14 d. A batch of the same fruit were placed at 0 °C, removed to 20 °C and exposed to hypoxia at monthly intervals for up to 5 months. Exposure to hypoxia decreased carbon dioxide production in Fuji apples at the preclimacteric and rising climacteric stages and at the climacteric. Respiration rate, ethylene production and volatile concentration of RG apples were not affected by exposure to hypoxia at any stage of ripeness or period at 0 °C. After exposure to hypoxia Fuji apples had enhanced ethyl esters at the preclimacteric and rising climacteric stages and after being at 0 °C for up to 5 months. Volatile concentrations were lower in apples maintained at 0 °C compared to noncooled apples. Apples at 0 °C had the greatest enhancement of ethyl esters after hypoxia suggesting that exposure to low temperatures did not just slow volatile biosynthesis but had an additional effect on volatile biosynthesis. Apple aroma consists of mainly low molecular weight esters produced by esterification of alcohol's by alcohol acyl CoA transferase (AAT) where acyl CoA's are substrates. Increased esterification activity in apples returned to air, following a hypoxic treatment, is due possibly to enhanced AAT activity or to competitive inhibition of other alcohols by ethanol. Concentrations of acetate and ethyl esters from skin disks of Cox's Orange Pippin, Fuji, Golden Delicious, Granny Smith, Pacific Rose, Red Delicious, Royal Gala, Splendour and Southern Snap apples exposed to 100% CO2 for 24 h at 20 °C, were compared to disks from control fruit, after addition of C2 to C6 alcohols, either individually, or as a mixture in equimolar amounts to the disks. Ethanol added as an individual alcohol induced high ethyl acetate concentrations, but when added as part of a mixture, little ethyl acetate was produced indicating substrate preference was for longer chain alcohols. Apple cultivars had four patterns of change in ester production after exposure to hypoxia: increased acetate and ethyl esters; increased acetate esters and decreased or no change in ethyl esters; no change or decreased acetate esters and increased ethyl esters; no change or decreased acetate esters and decreased or no change in ethyl esters, implying that AAT activity is affected differentially by hypoxia. Hypoxia induces changes in capacity to produce esters which last up to 7 d indicating that pre-storage treatments using hypoxia has the potential to change the aroma profile of apples. Juice of Fuji and Royal Gala apples exposed to a brief period of hypoxia (100% CO2 for 24 h at 20 °C) and ripened at 20 °C for up to 8 d, was analysed by taste panels using quantitative descriptive analysis. Hypoxia induced large increases in ethyl esters including ethyl butanoate and ethyl-2-methyl butanoate in Fuji apples but not in Royal Gala apples. There was no difference in average panellist scores for sensory characteristics for Fuji and Royal Gala apples at any sampling time. The lack of difference may have been due to large variation between panellist's assessment of sensory characteristics and/or inability to assess aroma, flavour and sweetness independently. A number of individual volatiles correlated with aroma in juice from apples exposed to hypoxia, including hexan-1-ol, butyl acetate, 2 methyl butyl acetate and propyl butanoate for Fuji; and ethanol, ethyl acetate, propyl acetate and propyl butanoate for Royal Gala. Multivariate analysis indicated that panellists associated increased ethyl esters with off flavour rather than more intense apple aroma. This could have been due to juice from apples exposed to hypoxia having a different apple-like character than control fruit which did not fit the definition of apple aroma used to train panellists. The enhanced ethyl ester concentrations in fruit exposed to hypoxia are probably due to large increases in ethanol concentration that competitively inhibited formation of non-ethyl esters. Golden Delicious and RG did not have enhanced concentration of ethyl esters and/or decreases in acetate ester concentration even though fermentation volatiles were enhanced to high concentrations and ethyl acetate increased to concentrations similar to those found in fruit which had enhanced ethyl esters. The mechanism producing ethyl acetate and ethyl esters in GD and RG was probably different from that in CO, FU, PR, RD, SP, SS cultivars. Therefore, after exposure to hypoxia, additional factors influence changes in volatile concentration other than the increased pool of substrate available for esterification. A possible mechanism by which hypoxia affects ester biosynthesis is that under hypoxic conditions cytoplasmic pH falls below the optimum of 7 to 8, inducing increased ADH activity and synthesis and producing large increases in ethanol concentration. Ester biosynthesis is suppressed during hypoxia leading to increased alcohol and aldehyde concentrations creating a pool of substrates that could be rapidly utilised by AAT on return to aerobic conditions. It is possible that AAT activity or concentration changes are induced by hypoxic conditions. The different capacity of apple cultivars to esterify alcohols from control and hypoxic treated fruit may be due to changes in substrate specificity of either, or both, newly induced ADH and AAT. Exposure to hypoxia consistently caused increases in ethyl esters in several apple cultivars. The practical uses for treatments where apples are exposed to hypoxia for 24 h include: disinfestation treatments, manufacture of apple juice concentrates, enhancement of aroma in apples maintained in long term air or controlled atmosphere storage and as a tool for examining volatile biosynthesis.