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    Model-based packaging design for minimising environmental impact of horticultural packaging systems : a thesis presented in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Food Technology at Massey University, New Zealand. EMBARGOED until 13 November 2026.
    (Massey University , 2024) Lozano, Raquel
    Packaging systems are instrumental in delivering high-quality food products to consumers. Food industries grapple with losses throughout the supply chain, resulting in both product and monetary setbacks. When considering the embodied resources in food production, including raw materials, energy, water, and emissions, minimising losses in any stage of the food supply chain is crucial. The New Zealand kiwifruit industry faces several constraints which include short harvest seasons, considerable distance to markets and year-round consumer demand. Packaging and storage plays a role in overcoming these factors by preventing undesirable quality loss traits. Establishing the link between packaging systems, supply chain conditions, and kiwifruit quality (specifically shrivel) provides a basis for evaluating the trade-off between over-packaging and excessing fruit loss. In this thesis, an integrated-mathematical model was developed to aid decision-making in for kiwifruit packaging, aiming to minimise the overall environmental impact throughout the kiwifruit supply chains from packhouse to purchase. This integrated-mathematical model facilitates exploratory analysis of both current and future supply chains and packaging systems. Four models were integrated: mass balance, moisture loss prediction, shrivel loss prediction and an optimisation engine. The mass balance model captured the kiwifruit and packaging masses and associated environmental impacts within kiwifruit supply chains. This model, applicable to any environmental metric, was developed to facilitate the prediction of kiwifruit losses. To validate its accuracy, the framework was applied in assessment examples, comparing its performance against existing research for kiwifruit supply chains. The absolute difference between predicted and actual emissions of CO2eq were less than 1% of the actual mean emissions at different stages of the supply chain. The moisture loss model was used to estimate kiwifruit weight loss both on a packaging unit and individual kiwifruit basis. The model demonstrated close agreement between weight loss predictions and experimental data for average packaging weight loss scenarios. Further refinement is needed to predict individual kiwifruit weight loss, specifically considering the impacts of packaging features on internal packaging water vapour distributions. The shrivel prediction model revealed that predicting kiwifruit losses due to shrivel posed challenges, primarily due to the current knowledge gap regarding the development of shrivel in kiwifruit under storage conditions. While increases in shrivel has been correlated to weight loss in existing literature, the reference state (at orchard, packhouse etc.) is arbitrary. Ideally shrivel would be related to an intrinsic property that could be measured at any point in time without requiring knowledge of this prior history of the fruit. The prediction of losses based on a non-relative starting point represents a knowledge gap addressed in this work, with potential improvements identified for future model iterations. This phase of the model development heavily relied on data collection to establish a mathematical relationship between weight loss and shrivel. The moisture loss and shrivel model served as the foundation for the development of an optimisation engine, enabling the identification of the optimal use of packaging. This model sought a balance between packaging mass and kiwifruit losses, employing various environmental impact categories as performance metrics. The success of this approach was evident as optimal packaging points were identified across (i) different packaging materials, (ii) different packaging materials and formats and (iii) different environmental impact categories. It was found that each optimum point for materials were unique to the ambient conditions of the supply chain, packaging format and material. This work revealed trade-offs between the environmental impact of the packaging material and amount of kiwifruit loss, numerically demonstrating what so far has only been presented as a theoretical concept in other research. Then, this integrated-model was applied to a range of real-life supply chain scenarios showcasing its versatility in addressing possible questions such as ‘what if ?’, ‘can we ?’ and ‘when can we ?. The application of the model to real-life scenarios demonstrated its utility for decision-making with respect to packaging materials and formats. This model is poised to offer crucial support for future packaging materials and supply chains. The limitation of this model lies in fruit loss predictions. To further model applicability, there remains further investigation of hypotheses developed during shrivel model development to refine the kiwifruit loss model. There also remains the opportunity to integrate more prediction models that account for the impact of packaging on other drivers of fruit loss, such as ethylene concentrations within the pack. While the integrated model developed in this thesis has some limitations in accurately predicting kiwifruit losses, this study highlights the significance of linking packaging performance and kiwifruit quality when evaluating environmental impacts. Although kiwifruit served as the focus in this work, the model created here paves the way for exploring the application of optimised packaging systems for other food commodities.
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    Assessment of the relationship between kiwifruit skin topography and its quality and storability using fringe projection : 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 22 November 2025.
    (Massey University, 2023) Lai, Po-Han (Leo)
    Kiwifruit harvested from different growing locations tends to have variable fruit quality and storage performance due to many preharvest factors that contribute to fruit variation at harvest. This variability of fruit between batches makes the prediction of postharvest storage quality difficult, causing postharvest fruit losses. One of the preharvest factors that introduces fruit variability is the growing environment in which the fruit are exposed to. Fruit skin, a protective layer that covers the entire fruit, plays an important role in fruit development and is the first point of interaction with the surrounding environment. The objective of this research was to investigate a novel non-destructive technique that utilised at-harvest skin topography to link with fruit quality and storage performance of kiwifruit. The ‘G3’ (marketed as SunGoldᵀᴹ) kiwifruit cultivar was chosen for consideration in this thesis because it has distinctive skin properties with protruding lenticels and is a high-value cultivar that is of considerable importance to the New Zealand kiwifruit industry. The potential for fringe projection to extract skin physical properties in kiwifruit was demonstrated through surface roughness quantification and image analysis technique. Characterisation of lenticels on the surface of kiwifruit was achieved by developing an automated image processing algorithm. The knowledge of the skin properties of kiwifruit was revealed through a comparison of skin topography and cuticle compositions of different kiwifruit cultivars. Skin topography differences revealed genotype related diversity as well as the effect of environmental factors that fruit were exposed to. The most abundant cutin monomer composed mainly of C₁₈. Predominant cuticular waxes such as fatty acids and phenolics were identified. The knowledge of lenticel development was confirmed through monitoring the skin topography during fruit development and fruit bagging. Lenticel formation becomes visible from 45 DAFB and is dictated in the early stage of fruit growth before 77 DAFB. Lenticel properties are set and established before harvest. An orchard bagging experiment revealed that the difference in the growing environment modified the development of lenticels in kiwifruit. The lenticel coverage was positively correlated with the humidity condition that the fruit is exposed to during fruit development. Lenticel density and size at harvest had little influence on the water loss and storage performance of fruit. Lenticels were found to become a low resistance pathway for water loss if there is evidence of microcraking and splitting. The hypothesis of using at-harvest skin topography to predict the post-storage quality of kiwifruit was explored by developing a blackbox machine learning model. Unfortunately, both quantitative and qualitative predictions of soluble solids and flesh firmness in storage were not successful due to a low level of accuracy across models. The storability of fruit is affected by many factors, and improvements can be made to include additional information such as other non-destructive techniques to help in prediction. While skin topography using fringe projection may not be a good indicator of kiwifruit storability, the application is useful to characterise skin properties that are related to fruit quality. The work found that skin roughness generally increases after storage which is likely to be caused by shrivel development or skin scuffing. There is an opportunity to rapidly and reliably quantify skin defects. Another potential application for fringe projection is to use in a kiwifruit breeding program as a high-throughput phenotyping tool to capture the surface properties of different genotypes, enabling the identification of desirable traits.
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    Ethylene related ripening of 'SunGold™' kiwifruit : 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 31 January 2026.
    (Massey University, 2020) Tongonya, Jeritah
    A key component of the success of the New Zealand kiwifruit industry is the consistent provision of high-quality produce. The projected increase in kiwifruit volumes necessitates the widening of harvest and marketing windows. Two different kiwifruit export marketing strategies are currently deployed: i) Early season fruit are delivered for immediate sale (‘KiwiStart’), ii) later season fruit have a maturity that enables extended postharvest cool storage (‘MainPack’). These marketing strategies determine harvest criteria and subsequent postharvest management practices employed in the supply cool chain. The introduction of new cultivars, e.g. ‘SunGold™’, necessitates a re-evaluation of the postharvest ripening and storage practices, tuning the requirements to the specific responses of each cultivar. Since there is minimal information on ethylene related responses for ‘SunGold™’, research to develop a fundamental understanding of these responses is crucial for optimal management and performance of the product in the market. The purpose of this PhD is to determine the effect of industry-relevant ethylene concentrations on ‘SunGold™’ quality progression (firmness and soluble solids content (SSC)). With that understanding, a semi-mechanistic model for the simultaneous description of firmness decline and soluble solids increase under dynamic temperature conditions and ethylene concentrations was developed.--Shortened abstract
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    Colour variation of red kiwifruit and environmental factors affecting its colour expression : a thesis presented in partial fulfilment of the requirements for the degree of Master of AgriScience in Horticulture at Massey University, Palmerston North, New Zealand
    (Massey University, 2015) Henwood, Roxanne
    Development of a red kiwifruit cultivar with good size, storage ability, and colour is desirable as the genetic potential exists and it could expand the market for kiwifruit. However, red kiwifruit cultivars, including the subject of this thesis, frequently have inconsistent colour. This thesis aimed to quantify colour variation of this red cultivar and the levels at which this occurred, as well as examining environmental factors (chiefly temperature and light) that may influence colour variation. To achieve this, two harvests were collected in March to May 2014 from eight trial blocks located in five regions around New Zealand (Far North, Western Bay of Plenty, Eastern Bay of Plenty, Gisborne, and Nelson). Orchard information was collected, including within orchard temperature variation via X-Sense temperature loggers, and fruit was assessed for maturity attributes and colour using subjective and objective tests. It was found that the greatest colour variation was at the orchard and region level, though variation between vines and positions within a vine was also significant. Region was not the largest influence on colour, as out of the three regions with two orchards, two of them had both high and low colour orchards. Colour was significantly predicted by fruit firmness, estimated light exposure, numbers of leaf layers, and skin colour in a linear mixed effects model. Lower firmness related to higher colour, as did paler, less exposed fruit with a higher number of leaf layers. The effects of light and leafiness may have been mediated by temperature, as carbohydrate supply seemed to be a less important factor for colour. Temperature was not formally identified as a significant factor; however, a relationship between flesh colour and temperature was implied by light exposure data and by scatterplots. These relationships may have implications for canopy management of this variety. Further investigation of the relationship between light exposure, fruit temperature, and colour may be helpful for determining appropriate management practices for this variety. Additionally, further work on temperature may provide a basis for predicting the colour expected in a given season.