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    Mathematical modelling of airflow during forced draft precooling operations : 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, 2024-11-01) Tapia Zapata, Nicolas Ignacio
    By the year 2020, the kiwifruit industry represents approximately 37 % of the horticultural export industry sector in New Zealand. Thereof, the kiwifruit cold chain aim is to reduce losses due to poor temperature control and energy usage during refrigeration. By forced convection aided by fans in palletised kiwifruit, field heat is removed rapidly prior to storage, thus optimising shelflife of the produce. Previous Computer Fluid Dynamics (CFD) model determined the optimal operating point for palletised kiwifruit during forced-draft cooling. However, CFD requires complex simulation, in detriment to computational efficiency and solving time. Therefore, there is an imperative to provide innovative tools that optimise package design by iterating several designs and that is applicable to the local industry sector for cold chain optimisation. In this spirit, this projects aimed to development of a simplified approach for the prediction of airflow distribution of palletised kiwifruit during forced-draft cooling, that can be coupled with an alternative heat transfer model, thus providing a fast and robust package optimisation routine that can inform cooling performance of several package design and pallet configuration.
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    Effects of Green and Gold Kiwifruit Varieties on Antioxidant Neuroprotective Potential in Pigs as a Model for Human Adults.
    (MDPI (Basel, Switzerland), 2024-04-09) Kanon AP; Giezenaar C; Roy NC; Jayawardana IA; Lomiwes D; Montoya CA; McNabb WC; Henare SJ; Digiacomo M
    Kiwifruit (KF) has shown neuroprotective potential in cell-based and rodent models by augmenting the capacity of endogenous antioxidant systems. This study aimed to determine whether KF consumption modulates the antioxidant capacity of plasma and brain tissue in growing pigs. Eighteen male pigs were divided equally into three groups: (1) bread, (2) bread + Actinidia deliciosa cv. 'Hayward' (green-fleshed), and (3) bread + A. chinensis cv. 'Hort16A' (yellow-fleshed). Following consumption of the diets for eight days, plasma and brain tissue (brain stem, corpus striatum, hippocampus, and prefrontal cortex) were collected and measured for biomarkers of antioxidant capacity, enzyme activity, and protein expression assessments. Green KF significantly increased ferric-reducing antioxidant potential (FRAP) in plasma and all brain regions compared with the bread-only diet. Gold KF increased plasma ascorbate concentration and trended towards reducing acetylcholinesterase activity in the brain compared with the bread-only diet. Pearson correlation analysis revealed a significant positive correlation between FRAP in the brain stem, prefrontal cortex, and hippocampus with the total polyphenol concentration of dietary interventions. These findings provide exploratory evidence for the benefits of KF constituents in augmenting the brain's antioxidant capacity that may support neurological homeostasis during oxidative stress.
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    Acute effects of fresh versus dried Hayward green kiwifruit on sleep quality, mood, and sleep-related urinary metabolites in healthy young men with good and poor sleep quality
    (Frontiers Media S.A., 2023-03-14) Kanon AP; Giezenaar C; Roy NC; McNabb WC; Henare SJ; Scholey A
    Background and aims: Daily kiwifruit (KF) consumption has been associated with improved sleep quality, but underlying physiological mechanisms are unknown. This study examined acute effects of fresh and dried green KF, compared with a water control, on sleep quality, mood, and urinary serotonin and melatonin metabolite concentrations. Methods: 24 men (age: 29 ± 1 years, body mass index: 24 ± 1 kg/m2) with poor (n = 12) or good (n = 12) sleep quality participated in a randomized, single-blind crossover study. One of three treatments was consumed with a standardized evening meal; (1) the flesh of two fresh green KF, (2) dried green KF powder (including skin; equivalent to dry matter of two fresh KF) mixed with water, or (3) a water control, in their own home. Subjective and objective sleep quality, mood, waking urinary 5-hydroxyindoleacetic acid (5-HIAA), 6-sulfatoxymelatonin (aMT6s), vitamin C and B-vitamin concentrations were determined. Results: Regardless of sleep quality group, compared to control, morning sleepiness, alertness upon awakening, and vigor were improved (p < 0.05) after dried KF consumption. Compared to control, both fresh and dried KF treatments tended (p < 0.1) toward improved esteem and total mood disturbance. Both KF treatments increased (fresh +1.56 ± 0.4 ng/g, p = 0.001; dried: +1.30 ± 0.4 ng/g, p = 0.004) urinary concentration of the serotonin metabolite 5-HIAA compared to the control (4.32 ± 0.4 ng/g). In poor sleepers, ease of awakening improved by 24% after dried KF consumption (p = 0.005) and tended to improve by 13% after fresh KF intake (p = 0.052) compared to the control. Good sleepers tended toward 9% improved ratings of getting to sleep with fresh KF (p = 0.053) compared to the control. Poor sleepers had lower amounts of some B-vitamins compared to good sleepers (p < 0.05). Conclusion: Consumption of dried or fresh KF with a standard evening meal, was associated with improved aspects of sleep quality and mood, possibly mediated through changes in serotonin metabolism. Clinical trial registration: [www.anzctr.org.au], identifier [ACTRN12621000046808].
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    Development of a novel methodology for the measurement of Red19 kiwifruit colour quality : a thesis presented in partial fulfilment of the requirements for the degree of Master of Engineering in Mechatronics, Massey University, New Zealand
    (Massey University, 2021) Lockwood-Geck, Samuel A.
    Consumers love visually appealing fruit. Colour is a key aspect of this appeal and is determined by a multitude of physical and psychophysical phenomena. Compared to its green and gold counterparts, the colour of red kiwifruit is not easily measured using existing techniques due to the spatially varying nature of its flesh colour. Red19 kiwifruit’s flesh colour often presents as a mixture of green, yellow, and red to varying degrees. The current method used to measure kiwifruit redness is by a subjective observer, but this produces a noisy and unreliable dataset which makes quality control difficult. The objective of this thesis is to create a colour measurement system for Red19 kiwifruit that transforms the current qualitative system into a quantitative system that can be utilised by the kiwifruit industry to produce standard and reliable measures of kiwifruit redness. Considering this goal, this thesis aims to explore what constitutes an objective grading scale of Red19 kiwifruit, and how a colour measurement system might be created that is invariant to changes in illuminant and spectral sensitivity (observers) and how this system could be deployed on a typical consumer smartphone. This thesis presents a comprehensive exploration of colour constancy in relation to red kiwifruit. A new scale of redness is proposed, and a small sensory trial was undertaken to validate this scale. A dataset of hyperspectral and raw images was collected and utilised to create a model that estimates the average reflectance of a single red kiwifruit. Another model was then created to regress from the average reflectance of a kiwifruit to a final redness score where fruit were graded based on the outcome of the sensory trial. The new redness scale proposed therein spans a range of 0 to 10,000 and is calculated by taking the difference of a kiwifruit’s average red and green RGB channel in the AdobeRGB colour space. This range was also divided by five to produce alternative class-based scale containing five classes each spanning sections of 2000 units over the new redness scale. This discrete scale is similar to the current qualitative scale used by Zespri to assess the colour of red kiwifruit. Through the application of a convolutional machine learning model, the average reflectance spectra of a kiwifruit can be estimated producing an RMSE of 0.0109 and 0.0096 over the visible and visible NIR spectral ranges. A general regression model is then used to regress from a kiwifruit’s average reflectance spectra to a final redness score and this produces a mean absolute error of 213.82 with a standard deviation of 213.82 which is equivalent to an average error of 2.2% and standard deviation of 2.13% when considering the full range of scores on the redness scale. These models are then combined to produce a final model, named KiwiNet, that produces a correct kiwifruit classification rate of 91.06%. This model has been demonstrated to run on a typical consumer smartphone and can produce a reflectance estimate and redness score for each kiwifruit. This model has been demonstrated to be invariant to five different illuminants and twelve different spectral sensitivities. Future work should look to carry out a larger sensory trial and explicitly corelate the proposed redness scale to the existing one. Likewise, this study highlighted that a kiwifruit image taken at 583nm appears to be used by the model to estimate kiwifruit redness score and work to reconstruct this wavelength from RGB/RAW images could provide a single measure of redness in the future.