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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 Investigating the health benefits of Monty’s Surprise apple phytochemicals : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Nutritional Science at Massey University, Manawatū, New Zealand. EMBARGOED until 18 November 2027.(Massey University, 2024) Nezbedová, LindaCancer is a major health concern worldwide, requiring effective prevention strategies to reduce its burden. There is evidence suggesting that diet plays an important role in disease prevention. Apples are an example of a commonly available fruit that can be easily incorporated into a diet to reduce the risk of chronic disease and some cancers. Apples are rich in phytochemicals with chemo-preventative properties. However, assessing their benefits in humans is complex due to various factors affecting phytochemical composition and low bioavailability. Understanding and controlling for these factors is crucial for maximising their potential in preventing cancer and promoting human health. The PhD project presented in this thesis uses a multidisciplinary ‘from orchard to fork to function’ approach to evaluate the health benefits of phytochemicals in a New Zealand heritage apple cultivar known as Monty’s Surprise, with an emphasis on cancer prevention. This thesis particularly focuses on apple’s most abundant phytochemical group known as phenolic compounds. After controlling fruit harvest and maturity, Monty’s Surprise apple was found to contain high concentrations of health beneficial phenolics, especially procyanidins, with apple skin having higher total phenolic content compared to its flesh. Pureeing was identified as a suitable processing technique with minimal impact on apple’s phenolics, allowing long-term preservation and creating uniform material for use in intervention and feeding trials. Moreover, Monty’s Surprise apple extract depleted of sugars inhibited the proliferation of lung, breast, and colorectal cancer cells in a dose-dependent manner in vitro. Lastly, in a human acute feeding trial, Monty’s Surprise apple puree increased plasma antioxidant capacity and decreased postprandial glucose response compared to sugar-matched placebo. The feeding trial also showed that procyanidins were not detected in the participant’s blood, while epicatechin and chlorogenic acid, which are prevalent phenolics in Monty’s Surprise apple puree, were absorbed into the bloodstream. Therefore, these compounds were available to contribute to the improved health parameters measured in the study. This study offers practical recommendations for optimising harvesting, storage, and processing practices to preserve and more clearly elucidate the health-promoting properties of phenolics in apples. Overall, this research demonstrated the potential health benefits of Monty’s Surprise apple and its phenolics, suggesting its value as a functional food for improving human health and well-being.Item Understanding kiwifruit postharvest physiology and quality changes in tropical retail market conditions : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Food Technology at Massey University, New Zealand(Massey University, 2022) Malavalli Veeregowda, Praveen KumarKiwifruit is New Zealand’s major horticulture crop. A challenge that exists for the New Zealand kiwifruit industry in emerging tropical markets is maintaining fruit quality during marketing. In Asia and the Middle East, high ambient temperatures (> 30 °C) are often prevalent. The domination of traditional fruit marketing practices in these regions results in fruit exposure to these conditions. Understanding of fruit postharvest responses to high ambient temperatures is limited. In this thesis, a supply chain survey was conducted in India and Singapore, where kiwifruit at edible ripeness were found to be exposed to temperatures > 30 °C and ethylene concentrations as high as 150 nL L-1 during retail. Back in the laboratory, kiwifruit were exposed to simulated tropical conditions, where 12 h of exposure to 40 °C resulted in significant changes in fruit physiology as evidenced by rapid respiratory decline. The findings from this initial study indicated that 40 °C exposure may have a lethal impact on kiwifruit whilst 33 °C may not. The role of ethylene in influencing kiwifruit physiology under tropical conditions was investigated by treating kiwifruit with 1-MCP to prevent ethylene responses. Consequently, 1-MCP treated fruit exposed to 33 °C retained firmness both in the presence or absence of exogenous ethylene whilst untreated fruit softened rapidly, indicating that the possible ethylene exposure in tropical conditions advances kiwifruit softening. A further study aimed to identify exposure temperature and time combinations that trigger detrimental outcomes for kiwifruit including after a period returned to coolstorage. Like previous, kiwifruit at 40 °C exhibited rapid respiratory decline, while at 33-38 °C, no such response was evident. This confirmed that 40 °C exposure for 12 h could have a lethal impact on kiwifruit physiology. Fruit that were exposed to high temperatures (33-40 °C) beyond 24 h and later coolstored developed internal breakdown symptoms indicating that irrecoverable degradative processes are induced. A plausible mechanism as a result of heat exposure is the occurrence of anaerobic respiratory metabolism. At 33-40 °C, Respiratory Quotient (RQ) in kiwifruit remained ≥ 1 reaching 3 at 40 °C whilst at 20 °C, RQ remained close to 1. Contrastingly, ethanol accumulation increased at high temperatures but minimal ethanol content changes occurred at 20 °C. At some high temperatures, ethanol content increased with time but no symptoms of heat injury were evident, suggesting that heat injury may not be exclusively caused by the accumulation of anaerobic metabolites. The increase in ethanol content measured in kiwifruit at high temperatures indicates the potential risk of off-flavour development at retail conditions in tropical markets. Overall, this research contributes to kiwifruit quality maintenance in tropical markets by elucidating safe exposure durations for kiwifruit and identifying a postharvest treatment of 1-MCP as a potential quality maintenance tool. Future research requirements include identifying molecular mechanisms that control physiological changes in kiwifruit at high temperatures, identifying causes for the differential responses observed between ‘Hayward’ and ‘SunGold™’ and investigating the efficacy of 1-MCP at wider ranges of high temperature conditions.Item Identification of mechanical parameters to be used as a firmness standard on quality evaluations of stored blueberry : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Plant Science at Massey University, Manawatu, New Zealand(Massey University, 2022) Rivera Smith, SebastianBlueberry firmness is considered a relevant quality variable influencing consumer acceptability of fresh blueberries. However, the blueberry supply chain and research community have not yet adopted a standard method to measure firmness on postharvest quality evaluations. This thesis has focused on characterising the mechanical properties of blueberry ‘Nui’ and ‘Rahi’ as influenced by different factors such as storage relative humidity (i.e., fruit water loss), controlled atmosphere and harvest maturity. The mechanical parameters were obtained by using the instrumental methods of texture profile analysis (TPA) equipped with a flat plate and the penetration test equipped with a 0.39 mm round tip diameter needle probe. Mechanical parameters of hardness slope (BHS, also known as chord stiffness) of TPA and displacement at skin break (DSk) of the penetration test can be used to track water loss changes in stored blueberries. The DSk and BHS can also accurately detect quality changes induced by controlled atmosphere storage. In addition, BHS can detect maturity differences in stored blueberries, but the force at skin break (FSk) provides better detection of maturity differences at harvest evaluations. To demonstrate the relevance of chord stiffness evaluations at a commercial level, sensory evaluation of texture of hand-touch firmness using a formal sensory panel setting and trained assessors was related to instrumental mechanical parameters. Chord stiffness measured as BHS using a flat plate compression and skin break slope (SSk) measured using a needle probe were strongly related to consumer sensory perception of hand-touch firmness. A blueberry batch with an average BHS ≤0.47 kN m⁻¹ or SSk ≤0.13 kN m⁻¹ was associated with a very high likelihood of unmarketable berries (i.e., berries are ‘soft’ or ‘very soft’). In summary, BHS was an informative parameter of blueberry quality across factors inducing the textural changes and providing commercially relevant information about consumer acceptability. These results can assist the development of a standard instrumental method to measure postharvest firmness on blueberry quality evaluations for research and commercial purposes. Further studies should focus on validating the feasibility of BHS to determine blueberry quality across other sources of textural variation, such as calcium and ethylene-related treatments. In addition, threshold values for mechanical parameters related to consumer acceptance (sensory analysis) may be identified across an extensive range of blueberry genotypes and using other sensory descriptors also relevant to the consumers, such as crispness. Finally, this research identifies alternative areas for further studies, such as the blueberry firming (an increase of firmness during storage) occurring consistently on blueberries ‘Nui’ stored under high RH in regular air or a controlled atmosphere of 5 kPa CO₂ + 4 kPa O₂.Item Characterising texture and cellular level responses of 'Centurion' blueberries during storage in different weight loss conditions : a thesis presented in partial fulfilment of the requirements for the degree of Master of Food Technology at Massey University, Albany, New Zealand(Massey University, 2019) Franklin, Deena KelseyPostharvest blueberry softening hinders consumer acceptance and correlates with high moisture loss during storage. Such textural variations have been attributed to factors such as turgor, cell wall modifications and other microstructural changes in the outer cell layers of the fruit. This thesis investigated the impact of moisture loss on blueberry quality, as well as the structure/function relationships associated with fruit texture characteristics during postharvest using an integrated physical and microstructural approach. Four different weight loss conditions (62%, 76%, 93% and 98% RH) were evaluated over a three week postharvest storage period to assess blueberry texture parameters using a texture analyser, where microstructural changes were assessed by light microscopy and optical coherence tomography (OCT). Under high weight loss conditions there was an increase in berry softening and a decrease in texture characteristics whereas an increase in berry firmness, hardness and gumminess was observed during storage under low weight loss conditions. Light microscopy clearly illustrated microstructural differences among ‘Centurion’ blueberries stored in different weight loss conditions, in retention of cell shape, degree of cell to cell wall contact, the amount of space between cells and cell wall integrity. When berries lost moisture during storage, epidermal and subepidermal cells retained their integrity, and parenchyma cells lost integrity leading to collapse which may contribute to overall fruit quality during postharvest. 3D OCT images showed no obvious differentiation between large cells at each weight loss treatment, however significant differences were observed in the microstructure between each storage period. In general the microstructure of medium to large cells in the parenchyma tissue showed an increase in average surface area and total surface area after each storage period. In summary, low weight loss storage conditions help to preserve blueberry texture and quality, whilst maintaining cellular structure and integrity during postharvest storage. It is recommended blueberries are stored between 95 – 99% RH and at a low temperatures to prevent moisture loss during postharvest.Item Regulation of postharvest inflorescence senescence in Arabidopsis thaliana : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Plant Science at Massey University, Palmerston North, New Zealand(Massey University, 2020) Xu, XiSenescence is critical for plant survival and fitness as it ensures the most efficient use of nutrients for development and production of offspring. Senescence is a genetically controlled and hormone-mediated programme. Besides being induced in an age-dependent manner, senescence can also be initiated precociously from harvest-induced stress such as light- and sugar-deprivation. Understanding the biological mechanisms behind dark-mediated senescence is important as it helps to provide a new strategy for extending shelf life of crop plants. This project aims to understand the regulation of dark-induced inflorescence senescence in model plant Arabidopsis thaliana by using a forward genetic approach. Arabidopsis mutants showing accelerated and delayed inflorescence senescence (named ais and dis) were identified previously. Here, I rescreened 23 mutants and confirmed the altered time to senescence phenotype of nine mutants, including two ais and seven dis mutants. Of those, the dis2, dis9, dis15 and dis51 mutants were used for further analysis. The delayed degreening phenotype was also observed in detached dark-held leaves of dis2 and dis51 mutants, indicating that the causal mutations affected genes that regulate both leaf and inflorescence senescence. Segregation analysis was used to determine the genetic nature of dis traits in the dis2 and dis51 mutants. The dis2 trait was found to be monogenic recessive while the dis51 trait is dual-genic recessive. The dis2 mutant showed an extended “stay-green” phenotype and retained higher chlorophyll (Chl) b than Chl a. These findings were consistent with a lesion in the NON-YELLOW COLORING1 (NYC1) gene. Sequencing revealed a C/T transition in exon 8 of NYC1, which caused a highly conserved proline to be substituted by serine at amino acid position 360 of the NYC1 protein. By contrast, dis51 retained a similar amount of Chl a and Chl b. One of the genetic lesions in this mutant was mapped to a ~665 kb region at the top arm of chromosome 5 by using High Resolution Melt (HRM)-based mapping technology. The ETHYLENE INSENSITIVE2 (EIN2) gene was considered as a promising candidate because similar phenotypes were observed in ein2 mutants and dis51 seedlings did not show triple response when treated with the ethylene precursor ACC in the dark. PCR-based sequencing showed a G to A mutation in exon 6 of EIN2, resulting in a premature stop codon, which thereby resulted in a truncated EIN2 protein missing part of the C-terminal region that is required for ethylene signal transduction. In addition, the dis51 mutant emitted a pleasant aroma, which is abnormal in Arabidopsis. Four compounds (benzaldehyde, benzyl alcohol, phenylacetaldehyde and phenylethanol) were detected by using GC-MS analysis. However, it is not clear if the mutation causing the aroma phenotype also contributed to the dis51 phenotype. The mutations in the dis9 and dis15 mutants were previously mapped to chromosome 3 and chromosome 2, respectively. Here, further HRM and whole genome sequencing (WGS) data analyses were used to identify the causal mutation in the dis9 mutant. The mutation changed a highly conserved Ser-97 to Phe in the active site of strigolactone (SL) receptor gene DWARF14 (D14), likely causing loss-of-activity. Since dis15 showed similar phenotypes to dis9, I hypothesised that the genetic lesion in dis15 may also have occurred in an SL pathway gene. The MORE AXIALLY GROWTH1 (MAX1) SL biosynthesis gene was present within the previously mapped region of this mutant. By using WGS data, I found a G/A mutation in the coding region of MAX1. The mutation in MAX1 substituted a highly conserved Gly-469 (G469) with Arg (R) in the haem-iron ligand signature of the Cytochrome P450 proteins. Using a N. benthamiana transient expression system, I found that the G469R substitution caused loss-of-activity of MAX1. In addition, the delayed sepal degreening of dis9 and dis15 was also observed in planta, suggesting a role of SL in regulation of both developmental and dark-induced sepal/inflorescence senescence. nCounter transcript counting technology was used to investigate the relationship between SL biosynthesis and signalling, sugar signalling and dark-induced senescence. There was no evidence of SL biosynthesis during the normal night in the inflorescences. During the extended night, the expression patterns of the SL biosynthetic gene MAX3 and signalling gene SUPPRESSOR OF MAX2-LIKE7 (SMXL7) best correlated with the sugar-responsive senescence regulatory genes [ARABIDOPSIS NAC DOMAIN CONTAINING PROTEIN92 (ANAC092) and NAC-LIKE, ACTIVATED BY AP3/PI (NAP)] and senescence marker gene (SENESCENCE-ASSOCIATED GENE12; SAG12), suggesting an interaction between SL and sugar signalling in controlling dark-induced inflorescence senescence. ANAC092 and NAP were further induced in the max1 mutant by the SL analogue, GR24, suggesting they are SL-inducible genes. The overall findings in this project reflect a complex regulatory network, which involves multiple phytohormones and degradation pathways, during dark-induced inflorescence senescence in Arabidopsis. Here, I proposed a model in which prolonged darkness first causes sugar-starvation in the excised inflorescence; the plant hormones ethylene and SL subsequently work together to regulate inflorescence senescence, including NYC1-regulated Chl degradation.Item Curing kiwifruit : physical, physiological and storage impacts : a thesis presented in partial fulfilment of the requirements for the degree of Master of Philosophy in Food Technology at Massey University, Auckland, New Zealand(Massey University, 2018) Doleh, LeilaCuring of ‘Hayward’ kiwifruit is a postharvest approach to reduce decay and maintain quality during long-term storage. Curing occurs immediately after harvest, with fruit placed in picking bins in a covered packhouse space for a few days. Curing contributes to fruit quality by allowing the picking scar to heal (resulting in reduced Botrytis rot) and allows a proportion of water loss, resulting in fruit cells that are less turgid and hence less prone to mechanical damage during packing. In the contemporary packhouse, curing is also used to buffer logistical challenges, since stockpiling fruit has advantages in ensuring the packing line continues to process fruit. In kiwifruit, the rates of cooling to storage temperature have previously been identified as an influence on long-term storage outcomes, including firmness and storage breakdown development (SBD). Little is known about how curing contributes to long-term storage, yet there is potential to impact post-storage fruit quality given that curing occurs immediately prior to packing and cooling. There is a lack of knowledge regarding the range of conditions which fruit are exposed to when bins are stacked under non-controlled conditions. It is also unknown how these conditions may influence fruit quality (i.e. fruit softening and SBD development) after long-term storage. This thesis incorporates monitoring of within bin environmental conditions to assess possible in-stack heterogeneity during curing.Item Developing non-destructive techniques to predict 'Hayward' kiwifruit storability : 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, 2017) Li, MoA significant portion of New Zealand’s kiwifruit production is held as stock in local coolstores for extended periods of time before being exported. Many re-harvest factors contribute to variation in fruit quality at harvest and during coolstorage, and results in the difficulty in segregating fruit for their storage outcomes. The objective of this work was to develop non-destructive techniques utilised at harvest to predict storability of individual or batches of ‘Hayward’ kiwifruit based on (near) skin properties. Segregation of fruit with low storage potential at harvest could enable that fruit to be sold earlier in the season reducing total fruit loss and improving profitability later in the season. The potential for optical coherence tomography (OCT) to detect near surface cellular structural differences in kiwifruit as a result of preharvest factors was demonstrated through quantitative image analysis of 3D OCT images of intact fruit from five commercial cultivars. Visualisation and characterisation of large parenchyma cells in the outer pericarp of kiwifruit was achieved by developing an automated image processing technique. This work established the usefulness of OCT to perform rapid analysis and differentiation of the microstructures of sub-surface cells between kiwifruit cultivars. However, the effects of preharvest conditions between batches of fruit within a cultivar were not detectable from image analysis and hence, the ability to provide segregation or prediction for fruit from the same cultivar was assumed to be limited. Total soluble solids concentration (TSS) and flesh firmness (FF) are two important quality attributes indicating the eating quality and storability of stored kiwifruit. Prediction of TSS and FF using non-destructive techniques would allow strategic marketing of fruit. This work demonstrated that visible-near-infrared (Vis-NIR) spectroscopy could be utilised as the sole input at harvest, to provide quantitative prediction of post-storage TSS by generating blackbox regression models. However the level of accuracy achieved was not adequate for online sorting purposes. Quantitative prediction of FF remained unsuccessful. Improved ways of physical measurements for FF may help reduce the undesirable variation observed on the same fruit and increase prediction capability. More promising results were obtained by developing blackbox classification models using Vis-NIR spectroscopy at harvest to segregate storability of individual kiwifruit based on the export FF criterion of 1 kgf (9.8 N). Through appropriate machine learning techniques, the surface properties of fruit at harvest captured in the form of spectral data were correlated to post-storage FF via pattern recognition. The best prediction was obtained for fruit stored at 0°C for 125 days: approximately 50% of the soft fruit and 80% of the good fruit could be identified. The developed model was capable of performing classification both within (at the fruit level) and between grower lines. Model validation suggested that segregation between grower lines at harvest achieved 30% reduction in soft fruit after storage. Should the model be applied in the industry to enable sequential marketing, $11.2 million NZD/annum could be saved because of reduced fruit loss, repacking and condition checking costs.Item Effects of temperature and coating treatment on gas exchange of 'Braeburn' apples : a thesis presented in partial fulfilment of the requirements for the degree of Master of Applied Science at Massey University(Massey University, 1999) Cheng, QingminAchieving modified atmosphere (MA) effects on fruit through the use of surface coatings relies upon a suitable degree of internal atmosphere modification, which is strongly dependent upon both respiration rate and skin permeance to gases. In this study, skin porosity, skin permeance, internal partial pressures of oxygen and carbon dioxide, and respiration rate were measured at 0°C, 10°C, 20°C and 30°C in non-coated 'Braeburn' apples. Variation in respiration rate, internal partial pressures of oxygen and carbon dioxide, skin permeance to oxygen and carbon dioxide, and the extent to which all of these gas exchange characteristics affected by temperatures of 0°C, 5°C, 10°C, 15°C, 20°C were characterised in both non-coated and coated 'Braebum' apples. Coating treatments were 0, 0.2, 0.4, 0.6, 0.8 and 1.0 times either a 2% (w/w) solution of hydroxypropylcellulose (HPC) in distilled water, or a commercial formulation of carnauba wax and shellac coating, achieved by mixing the full strength solutions with distilled water. There was a 6- or 10-fold difference in respiration rate between fruit kept at 0°C and 20°C, or 0°C and 30°C, whilst the relative permeance to both O 2 and CO 2 differed only a factor of 1.7 or 1.5 in non-coated fruit. The differing effects of temperature upon these two variables were responsible for the depression of internal O 2 and elevation of internal CO 2 associated with increase in temperature from 0°C to 20°C or 30°C. There was no evidence that porosity was dependent on temperature, suggesting that the increasing permeance with higher temperatures may have resulted from increasing permeance of the cuticle. The modification of internal atmosphere composition in carnauba-coated fruit depended upon coating concentration and temperature. The effects of HPC coating on internal atmosphere, especially on internal CO 2 were less marked than those of temperature. In non-coated fruit, the magnitude of decline in internal O 2 was slightly greater than the increase in internal CO 2 over the temperature range in the experiment. For apples that were respiring aerobically, this indicates that the fruit skin had a slightly higher permeance to CO 2 than to O 2 . Since O 2 diffuses through pores were readily than CO 2 , gas exchange of these fruit appeared not to be pore dominated. The suppression of gas exchange by shellac coating was consistent with the coating blocking pores on the fruit surface to an extent that depended on coating concentration. The less pronounced effects of HPC coating in both skin permeance and internal gases were consistent with a coating that loosely covered the fruit surface rather than blocking the pores. Low concentrations of shellac coating achieved low internal O 2 levels at higher temperatures but had only slight effects on internal atmosphere composition at low temperatures. Higher concentrations that achieved MA benefit at low temperatures resulted in fermentation at higher temperatures. Given the natural variability in skin permeance, and the exacerbating effects of coating treatment and temperature, surface coatings appear unlikely to provide a reliable and safe means of achieving modified atmosphere benefits in 'Braeburn' apples.Item Evaluation alternative methods of bruise measurements in apple fruit : a thesis presented in partial fulfilment of the requirements for the degree of Master of Applied Science in Institute of Technology and Engineering at Massey University(Massey University, 1998) Min, KuangA study has been conducted to compare different methods to measure bruise susceptibility of fruit. In order to compare measured values with actual commercial bruising, an appropriate test method to simulate impact damage during handling was developed, employing a revolving tumbler. From the analysis of bruise damage produced by the tumbler on four apple cultivars under different storage treatments, it was found that a large percentage of bruises were less than 1.5 cm in area, and the number of bruises above 1.5 cm did not change between treatments. It was concluded that laboratory measurements involving high impact energy levels may be insensitive as indicators of bruising levels on fruit during commercial operations. The impact loads produced by this method was very similar to those incurred by a practical grader, as indicated by Instrumented Sphere measurements. The tumbler test permitted examination of actual grader damage relationships with standard tests. Three standard impact tests (vertical drop test, double and single pendulum test) were conducted on four cultivar apples: Splendour, Granny Smith, Pacific Rose, and Braeburn. Four different shapes of impact surface were used for each impact test. It was found that bruise susceptibility varied with different impact tests. Regression analysis was made on the data obtained from standard impact tests and tumbler test to find the correlation between the bruise susceptibility and the bruise area/apple. Bruise susceptibility obtained from the vertical drop test using the hockey ball was closely related to the bruise area per apple produced by the tumbler test (R = 0.72). The bruise factor obtained from the single pendulum test using the flat indenter also showed a correlation with the bruise area per apple produced by the tumbler test (R = 0.78). However, the bruise susceptibility produced by the double pendulum test and single pendulum test was not well correlated with the bruise area/apple and bruise number/apple produced by tumbler test. The bruise susceptibility produced by using the pyramid indenters from three standard impact tests was not well correlated with the bruise area per apple and the number of bruises per apple produced by the tumbler test. Bruise susceptibility, bruise area, and the shape of the bruise depended upon the shape of the indenter used for the experiment and the method used to conduct the impact tests. Splendour, Granny Smith and Pacific Rose all had similar bruise susceptibilities, but Braeburn was significant less susceptible to bruising. Generally, bruise susceptibility increased with storage time in all cultivars. Apples stored in a low humidity environment (65% RH) generally had lower bruise susceptibilities after 2 months storage for the flat and hockey ball indenters but not for pyramid indenters on Splendour and Braeburn apples, when compared with 90% RH storage. Bruise susceptibilities at 0.5° C were higher than at room temperature. Fruit firmness also decreased with storage time. Bruise shape depended upon the indenter surface shape. The flatter indenters produced bruises which were less deep than the hockey ball and pyramids. The bruise shape was elliptical for the flat plate, a circle for the hockey ball, and a rhombic for the pyramid indenters. There was no cracking below the bruise region for any apples when the flat plate indenter was used in the three standard impact tests. However cracks were found below the bruise region in Splendour, Pacific Rose, and Braeburn apple (but not for Granny Smith apples) when any pyramid indenter was used. The pyramid indenters produced a more linear relationship between a 2/3 power impact energy and bruise area (without skin removal) than either a spherical or a flat indenter. Bruise visibility depended on the impact surface shape and energy levels. Some bruise produced from standard impact tests, when the flat indenter used, were not visible unless the apple skin was removed. Braeburn required a greater impact energy to produce an initial bruise than other cultivars. Once bruising began the visibility of bruising increased with an increase in energy levels.
