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Item Using non-destructive laser backscattering imaging technology for kiwifruit quality assessment : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Food Technology at Massey University, Manawatū, New Zealand(Massey University, 2024) Yang, ZhuoKiwifruit is one of the most important exported horticultural products in New Zealand. The supply of kiwifruit to both national and international markets can be extended by harvesting kiwifruit unripe and storing with proper postharvest practice. During kiwifruit storage, quality monitoring is required for inventory planning and consistent quality maintenance. Currently, the industry is using sampled data to represent a batch of kiwifruit. However, kiwifruit quality is difficult to estimate based on destructively measured samples due to the heterogeneous population quality distribution. Therefore, a non-destructive technology is preferred allowing quality measurement for all kiwifruit prior to and during storage, as well as before exporting and marketing. Commercial spectral-optical devices, such as near-infrared (NIR) spectroscopy, have been employed by the industry for fruit grading and sorting at harvest, and have achieved good performance in total soluble solid content (SSC) and dry matter content (DMC) estimation. However, NIR spectroscopy had a poorer performance in estimating kiwifruit flesh firmness (FF), the primary quality indicator. During light and fruit tissue interaction, those optical devices capture data containing primarily the absorption signal related to kiwifruit’s chemical composition. Therefore, the FF estimation is indirect and the accuracy of FF measurement is affected when both textural structures and SSC change during postharvest ripening. Laser backscattering imaging (LBI) records the backscattered signal after a single laser beam interacts with kiwifruit tissue. These light-tissue interactions include light absorption and scattering. The back-scattered signal could be analysed as an attenuation profile, and this attenuation profile is determined by optical properties of absorption (μa) and reduced scattering (μs’) coefficients, which correlate with fruit chemical compositions and physical properties, respectively. Therefore, LBI data is potentially helpful for FF estimation and early-stage internal disorder symptoms detection. This PhD work developed a non-destructive approach based on the LBI technique to segregate kiwifruit with internal disorders [brown marmorated stink bug (BMSB) feeding injury and chilling injury (CI)], as well as soft fruit at FF threshold of 9.8 N. Estimation of μa and μs’ was achieved with 56.6 % and 91.5 % accuracy respectively, using a pre-classification method and validated against optical phantoms of known optical properties. Additionally, LBI parameters directly extracted from the images were utilised to develop segregation models owing to the uncertainties in μa and μs’ estimation. For internal disorder detection, using the estimated kiwifruit μa and μs’, the segregation accuracy for kiwifruit with BMSB damage was 84 % and 62 % for ‘Zesy002’ (n=198) and ‘Hayward’ (n=198). Using extracted kiwifruit LBI parameters, the segregation accuracy for kiwifruit with CI was 92 % and 39 % for ‘Zesy002’ (n=396) and ‘Hayward’ (n=400). In addition, ‘Zesy002’ (n=30) and ‘Hayward’ (n=30) LBI during the postharvest ripening for kiwifruit were collected through a 15-day shelf life at 20 °C, where extracted LBI parameters were used to develop a time-series model. Absolute values of kiwifruit LBI parameters increased during the kiwifruit ripening process for both cultivars and the trend of LBI parameters may be correlated with kiwifruit softening. For segregating kiwifruit based on FF, the kiwifruit FF segregation model was calibrated, cross-validated and externally tested using kiwifruit LBI and corresponding FF data collected from 2 seasons with varying at-harvest maturity stages and stored at 2 temperatures. The segregation model accuracy for classifying fruit based on the 9.8 N FF threshold was 75 % and 70 % for ‘Zesy002’ (n=2247) and ‘Hayward’ (n=3558) in test sets. In conclusion, this work confirms that LBI technology has the potential for segregating soft kiwifruit or kiwifruit with early internal disorder symptoms and be adapted to the packhouse sorting system. However, in this work, FF segregation uncertainty at the 9.8 N threshold was observed when ‘Zesy002’ FF (N) ∈ (5,15) and ‘Hayward’ FF (N) ∈ (5,20) due to LBI parameter overlapping. Improved image analysis and segregation algorithms need to be investigated to enhance the segregation sensitivity for kiwifruit FF in the lower firmness range.Item Effect of traditional storage methods on post-harvest dormancy of Taewa Māori seed potato (Solanum tuberosum L.) in Aotearoa New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Plant Science, School of Agriculture and Environment, Massey University, Manawatu, New Zealand(Massey University, 2024) Sousa Carvalho, Marcos SchleidenIn the Solanaceae family, the potato (Solanum tuberosum L.) is one of the major tuber crops. In New Zealand there are potatoes called Taewa. Māori growers who grow these potatoes generally store the harvested seeds in dark places, at the ambient temperature and a large proportion of those growers generally store with dry fern coverage for at least four months before planting. The objective of this study was to evaluate the Māori storage method on the preservation of the seed potatoes. This experiment chose conditions to represent traditional methods, the major difference being temperature control. The Māori Storage Method (ambient and dark environment) was contrasted with the Conventional Storage Method for potatoes, which consisted of placing the potato seeds in a dark room at continuous temperature of 5˚C. The potato seeds used in the experiment were randomly selected, weighed. And then put into storage. Tubers were evaluated at 30-day intervals from the beginning to 120 days of storage. A randomized complete block design was applied with 3 blocks of the treatments. In the first experiment (2022), analyses of respiration rate, weight loss and sugar content were performed. In 2023 the same experiment was repeated with some changes i.e., measuring sprouting (length, width and number of sprouts in Taewa varieties), but not sugar content (SC), and doing respiration rate (RR) and weight loss (WL) again for comparison between the two trials. Data on the evaluated parameters were analysed using a linear mixed model (Mixed Procedure) with year, variety, storage method and their interactions as the fixed factors and block as the random factor following by a Tukey-Kramer test for multiple comparisons. An exponential regression model (Nlin Procedure) was applied to fit the data on the change of parameters evaluated, and the coefficients of determination (R2) for regressions were also calculated. The response variables (respiration rate, weight loss, and sugar content) presented characteristics of each variety, highlighting the Tutaekuri variety with the highest respiration rate and percentage of sugar content. The variety that showed the highest percentage of weight loss was Moemoe. The influence of environmental conditions during the storage period of the Māori method may have interfered with the dormancy period of Taewa potatoes in the response variables (respiration rate, weight loss, sugar content, and sprout). The tuber dormancy duration is largely dependent on the genotype along with pre-and postharvest conditions. The factor that most determined this characteristic was the storage temperature. In this experiment, storage temperature is the main environmental factor affecting tuber dormancy on Taewa potatoes. The tuber dormancy duration is largely dependent on the genotype along with pre-and postharvest conditions. In general, there is a lot of common ground between both cultural and commercial approaches to seed selection and storage.Item An integrated experimental and numerical approach to understand and address airflow and cooling variation in refrigerated shipping containers with kiwifruit pallets : 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 16 December 2026.(Massey University, 2024-11-26) Alaka, AbdulquadriNew Zealand's kiwifruit industry has been the most significant contributor to the country’s horticultural export value for many years. Despite facing recent unseasonable weather conditions and labour shortage challenges, the kiwifruit industry contributed approximately 38.5 % to New Zealand's total horticultural export value in 2023. NZ kiwifruit and other horticultural produce earnings largely come from distant markets such as Europe, Japan and China, representing one of the longest supply chains in the world. NZ's expanding kiwifruit export volume heavily relies on refrigerated containers to preserve and maintain fruit quality along the supply chain. This is vital to ensure that the industry continues supplying its overseas customers with high-quality products and attracting significant export earnings. Refrigerated containers are designed to maintain cargo temperature throughout transit. However, sub-optimal airflow distribution inside containers when fully loaded with pallets of fruit often results in temperature variation within the cargo. Unfortunately, such temperature variation comes with a significant economic disadvantage as it results in fruit losses via chilling and, or freezing injury as well as senescence. It also leads to variations in the quality of fruit of the same batches, complicating inventory management along the supply chain. Improving the airflow distribution within stowed refrigerated containers can go a long way in improving temperature or cooling uniformity within the system. This project combined experimental and computational approaches to understand and improve airflow and cooling uniformity inside containers stowed with kiwifruit pallets.--Shortened abstractItem Application of UV-C technology in extending the shelf life of fresh blueberries : a thesis presented in partial fulfilment of the requirements for the degree of Master of Food Technology at Massey University, Albany, New Zealand. EMBARGOED until 1st August 2027(Massey University, 2024) Akram, SidraFresh blueberry fruit is highly perishable and susceptible to spoilage by bacteria and fungi resulting in a short postharvest shelf life. Ultraviolet light treatment (UV-C) in the range is considered an emerging novel food processing technique that can be used to improve fruit quality and thus prolong the shelf life. The study investigated the impact of UV-C light treatment on untreated fresh blueberry farthing variety. The study was conducted in three phases to analyse and optimize the most suitable dosages to be applied to the sample and determine its effects on the fruit sample during the 14 days of storage at 4°C. The fruit sample was collected from a local blueberry farm and transported to the Massey University, Auckland campus. In phase one, the fresh blueberry fruit was treated with different dosages of UV-C (50, 100, 200, 300, 400, 600 mJ/cm²) using a JouleSafe disinfection system. Focus group sensory evaluation was used to analyse the consumer acceptance of the UV-C treated fruit alongside the microbial enumeration to narrow down the range of dosages.--Shortened abstract.Item Imaging based measurement of density for the determination of dry matter and brix for ‘Hayward’, ‘SunGold’ and ‘RubyRed’ : a thesis presentation in partial fulfilment of the requirements of the degree of Masters in Food Technology and Post-Harvest at Massey University, Manawatu, New Zealand(Massey University, 2023) Palmer, Ruth AllisonThis research was conducted at both Massey University and Massey AgriFood Digital Foods, Manawatu, New Zealand. Three-dimensional scanning, volume submergence alongside the destructive experiments were conducted on more than 900 kiwifruit. Approximately 312 kiwifruits (RubyRed, SunGold and Hayward) for each cultivar from three different grower lines were tested and examined. The kiwifruits were all picked at harvest maturity, commercially graded, and placed in 0℃ refrigerator storage to maintain the harvest maturity. With advances in imaging technologies, it is now feasible to measure volume accurately and non-destructively and therefore density. The aim of this project is to revisit the relationship between density, DM, SSC for all three cultivars (RubyRed, SunGold and Hayward). This project will be determining the accuracy to which these can be estimated using imaging-based volume measurement. The results from this research will be able to assess the industrial opportunity for the exploitation of imaging technologies as a means of determining the important parameters of DM and SSC. The objectives of this work include: To see if this relationship exists in the three cultivars and to see if dry matter can be estimated non-destructively through this relationship combined with digital density determination. The literature review explored existing destructive and non-destructive methods for measuring the kiwifruit volume and therefore density. Non-destructive fruit volume estimation can be used as a ripeness index to predict optimum harvest time, yield or to study the relationship between fruit expansion rate and susceptibility to physiological disorders such as fruit softening. In a paper by Jordan, R. B. et. al (2000), the volume was measured through the determination of buoyant force and water being displaced where volume is calculated from the object weight and the force. The results across the three cultivars showed strong correlations between the digital volume and the submerged volume. For RubyRed and SunGold it was observed that volume, DM and density had good correlations with 72% for RubyRed and 77% for SunGold. In comparison Hayward had the weakest correlation with an R value of 42%. This was due to experimental conduct during covid-19, where lab time was limited thus influencing the timetable of experiments for Hayward. For all cultivars, the relationship between density and SSC was weak with R values of 45% (RubyRed), 20% (Hayward) and no correlation for SunGold.Item Understanding the storage potential of two blueberry cultivars grown in New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Horticulture at Massey University, Manawatū, New Zealand(Massey University, 2023) Pal, PranoyNovel blueberry cultivars such as Eureka (EU) and First Blush (FB) are usually picked, packed, handled, coolstored and commercially sold in the same punnet. However, these cultivars possess different fruit physiological and morphological attributes and consequently may behave differently as influenced by postharvest storage conditions. Two independent experiments were designed to provide a better understanding of the modes of failure (water loss, softening, and rots) as influenced by storage conditions. It is expected that these investigations will facilitate the blueberry industry to decide if these cultivars should be picked, packed and handled differently in the commercial supply chain. Experiment 1 was setup with four storage temperatures (0.5°C, 1.5°C, 2.5°C, and 3.5°C) as treatments using EU and FB cultivars. Response variables of weight loss (WL), firmness and rots were monitored at weekly intervals over 28 days. WL increased over time with highest WL (3.8-6.1%) at 3.5°C and the lowest WL (1.8-4.3%) at 0.5°C. Cultivar differences were observed with higher WL in the EU cultivar than the FB cultivar. Firmness decreased in both cultivars over time when stored at 2.5-3.5°C. When compared to at-harvest firmness, values after 28 days in storage did not decrease significantly at 0.5-1.5°C. Rot incidence was numerically higher at 3.5°C than 0.5-1.5°C for both cultivars, but could not be statistically verified. Experiment 2 investigated the effect of storage extension technologies, such as, modified atmosphere packaging (MAP) and sulphur dioxide (SO₂) pads on both cultivars and WL, firmness and rots monitored at weekly intervals when stored at 2°C over 42 days. Blueberries stored in MAP+SO₂ showed sevenfold less WL (1.5%) than control fruit (6.9-10.9%). In addition, MAP+SO₂ treatment had significantly less rots than the control. Cultivar differences were also observed with higher number of rots in the EU cultivar. However, MAP+SO₂ treatment caused SO₂ bleaching to both cultivars observed at all storage timings and hence the use of SO₂ pads is not recommended in these cultivars. Commercially, the blueberry punnets are packed with approximately 1-2% extra weight at packing to account for the WL during storage and handling. Results from these experiments demonstrate that both cultivars should be packed separately due to propensity of the EU cultivar to lose more moisture affecting the quantity of extra weight. The use of storage extension technologies (MAP and SO₂) did not show a significant commercial benefit. Future studies should focus on comparing the efficacy of using MAP vs a standard polyliner and/or creating SO₂ pads with a slower release rate.Item Rate controlling mechanisms in atmospheric freeze drying : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Chemical and Bioprocess Engineering at Massey University, Manawatū, New Zealand(Massey University, 2023) Mathew, MeritAtmospheric freeze drying (AFD) can be considered a cost-effective alternative to vacuum freeze drying (VFD) but the very slow drying rate associated with it limits industrial scale adoption. Nevertheless, there are applications, particularly with thin sections such as sliced fruit or leaves, for which hops is an example, where the rate of AFD is relatively high. Therefore, it is important to understand the rate-controlling mechanisms in AFD and how it is affected by the structure of the fruit or leaf. Such understanding will help identify the bottlenecks of the process and thus the steps that may be taken to overcome them. This project has developed a mathematical model for AFD by considering the intrinsic material properties and the theoretical principles of heat and mass transfer. This could help the end-users to run simulations of AFD for different products and arrive at the best drying strategies to achieve faster drying rates before doing time-consuming and expensive experiments. In this work, hops are considered as the model system for the model development. The study needed high-quality experimental data for continuous in-situ weight loss measurements during AFD and there was a lack of such data in the literature reviewed. To deliver this, part of the project has developed a new experimental apparatus. The experimental apparatus developed is capable of continuous weight-loss measurement and data logging temperature and RH of the air in the drying chamber. Temporal weight-loss trial data are used to fit parameters and predict the drying rate and product weight loss. During the study it was found that AFD of hops is a mass transfer limited process. The drying rate was found to increase with process temperature and the adsorbent to hops ratio. Air circulation also helped in increasing the drying rate. The one-dimensional model developed to simulate AFD of hops was able to predict the drying behaviour based on the process parameters and the fitting factors for the hops. Ice sublimation was also studied in this project, based on the hypothesis that the AFD of hops is a type of pure ice sublimation with an additional layer of resistance to mass transfer. This hypothesis was found to be true for the present case and the model was development based on this.Item Postharvest decay of blueberry fruit in New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Horticultural Science at Massey University, Manawatū, New Zealand(Massey University, 2023) Hosking, Jack EugenePostharvest decay limits the storage life of fresh blueberries and is unacceptable in export markets. Currently, no surveys have been conducted to determine the microorganisms causing decay of blueberry fruit during postharvest storage in New Zealand. Identification of the major microorganisms associated with postharvest decay is critical to effective management of decay within the supply chain. This thesis identifies the microorganisms associated with postharvest decay of blueberry fruit with the aim of observing the prevalence and nature of these rots after cold storage. Four combinations of temperature and relative humidity (RH) were used to store blueberry fruit. These treatments were obtained by a factorial combination of two temperatures, 1°C and 15°C, and two relative humidity (RH) conditions of high RH (98-100% RH) or low RH (80% RH). The 1°C storage at either RH was implemented for 42 d, while the 15°C storage had a duration of 14 d. Following storage, the fruit was stored at 20°C for 7 days to simulate shelf life (retail or home use), and decay prevalence evaluated. From the decay signs observed, microorganisms were isolated and identified through morphological and molecular analysis. The major microorganisms isolated from blueberry fruit decay were identified as Botrytis cinerea, Colletotrichum acutatum species complex, and Pestalotiopsis spp. Both B. cinerea and C. acutatum spp. complex are causal agents of decay signs, responsible for grey mould and anthracnose, respectively. Pestalotiopsis spp. was associated with decay of blueberry fruit, but it is unclear whether this is a causal agent of decay. The postharvest storage conditions influenced the prevalence and behaviour of decay. At 1°C, B. cinerea was the dominant causal agent of decay, leading to grey mould sign (extensive grey/tan mycelium) at 98-100% RH. When blueberries were stored at low RH (80%), B. cinerea infections were mostly restricted to the fruit stem scar. During shelf life, after 1°C storage for 42 days, decay showed a higher accumulation rate than when the fruit was stored at 15°C prior to shelf life. In addition, after shelf life, B. cinerea and the C. acutatum spp. complex were the most predominant causal organisms isolated from decayed fruit.Item A systematic approach for developing and manufacturing fruit simulators : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Food Engineering, Massey University, Palmerston North, New Zealand(Massey University, 2023) Huang, HuijianDue to the high cost, variable nature and seasonal availability of fruit, conducting large scale experiments for research purposes is not easy. A fruit simulator is a physical tool that mimics the mechanistic features and properties of the targeted fruit; hence, it can be used as a replacement for the fruit in research experiments. This study focuses on developing simulators for heat transfer experiments, especially in horticultural produce precooling. A framework for developing the simulator was established based on the importance of each mechanistic feature. Depending on the application's needs, the simulator can mimic different length scale levels of the targeted fruit, such as the individual fruit, the bulk stacking of the fruit or sub-units of the fruit (e.g., a punnet/bag of table grapes). The scale level determines whether certain mechanistic features are important and affects the values of the thermal properties that must be matched. For example, a simulator that mimics a punnet of fruit with enclosed air pockets has an effective thermal conductivity and volumetric heat capacity that includes contributions from the thermal properties of the fruit and air, which provides more room for material selection. Based on this framework, a systematic approach for the simulator manufacture and material selection was developed. Three different simulators were developed based on the framework: kiwifruit, apple and table grape simulators. The comparison of a simulator and real fruit precooling trials showed good agreement, validating the approach and demonstrating the feasibility of using simulators in postharvest research. The kiwifruit simulator was validated at different experimental scale levels, from individual kiwifruit to multiple kiwifruit boxes containing numerous individual kiwifruit simulators (which reflected pallet scale precooling). During the simulator development, the concept of a time-scaled approach was identified and was explored. In theory, if the volumetric heat capacity of a simulator becomes smaller while the Bi of the simulator remains the same, the heating/cooling time of the simulator in an experiment will decrease proportionally according to the Fourier number (Fo). This approach was validated via the three simulators developed in this study. The validation of the simulators confirms the feasibility of this time-scaled concept. This approach has a significant advantage in reducing the experimental time and easing the material selection process for the simulator manufacture. In the table grape simulator development, a process of using CT scans of the bulk packaged system to study the bulk shape and effective properties of the fruit subunits (bags) were developed, where the bulk shape and effective thermal properties of a bag of table grape were determined based on the process. A set of bag shaped fruit simulators was then manufactured with equivalent bulk thermal conductivity and used to validate the bulk simulator approach by comparison of cooling rates with real fruit. Overall, this study has successfully developed a generalised heat transfer simulator development framework. In addition, this study validated the feasibility and applicability of the time-scaling approach, which could be helpful for any future experiments. Furthermore, this study has developed a process to use CT scanning to determine a bulk object's bulk shape and effective property. The outcomes of the work pave the way for carrying out postharvest and packaging optimisation experimental trials with reduced variability, greater ease and without seasonal constraints. The simulator development framework provides a basis for further expansion of these concepts into other applications beyond the heat transfer focus that they were developed for in this work.Item Identification of fruit parameters related to calyx cavity incidence for the evaluation of non-destructive equipment as segregation tools : a thesis presented in partial fulfilment of the requirements for the degree of Master of Horticultural Science at Massey University, Palmerston North, New Zealand(Massey University, 2022) Longuet-Higgins, Josephine MarjorieCalyx cavity is a major physiological disorder in persimmon that hinders exports and correlates with reduced fruit quality during storage. Postharvest quality changes, including increases in softening and colouration, have been related to the presence of calyx cavity. This thesis investigated the impact of calyx cavity on persimmon quality using both destructive and non-destructive methods of evaluation and assessed the ability of these tools, combined with modelling techniques, to segregate affected fruit. Seven batches of ‘Fuyu’ persimmon were evaluated at the time of harvest and following a nine-week storage period in modified atmosphere packaging (MAP) at 1 °C. Quality parameters assessed were fruit size, texture, colour, sweetness, and severity of calyx cavity. Non-destructive methods used included near infrared spectroscopy (NIR), acoustic vibration and non-destructive compression; the destructive methods used were flesh firmness and soluble solids content (SSC). A visual scale was created to score the severity of calyx cavity from no separation (grade 1) to minor (2), moderate (3), and major separation (4). After storage, fruit firmness decreased, and SSC and external colouration increased compared to at harvest values. Large differences in fruit maturity, in terms of firmness, colour and SSC were observed between fruit from different harvest dates. The presence and severity of calyx cavity was correlated with greater colouration and greater weight. On average, a 40 g increase in weight and 1 – 2 unit increase in colour index was observed with each level (1 – 4) of calyx cavity severity. Using colour and weight data, binary classification of calyx cavity by linear discriminant analysis (LDA) had a total accuracy of 74.1% correct segregation. Random forest (RF) segregation of calyx cavity using NIR data had a performance metric of 0.655. The implementation of non-destructive calyx cavity classification based on the evaluation of changes in quality parameters would provide the ability to segregate healthy and affected fruit. However, the relatively low accuracy of these models creates limitations including yield losses and failed identification of fruit with calyx cavity. Further work is required to improve model performance including optimisation and validation of calyx cavity segregation models.
