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BACKGROUND Under-Skin Browning (USB) is a physiological skin disorder that significantly reduces quality of ?Honey Gold? mango (HG) fruit. Relationships between potential causative factors (vibration, holding temperature, sap) and expression factors (enzymes activities, phenolic concentration, anatomy) were investigated. RESULTS USB incidence was 2.6?3.6-fold higher in ripe HG fruit vibrated for 3?18?h at 12 °C to simulate transport damage and held then at 12 °C for 8?days compared to control fruit held under the same conditions. USB severity of fruit lightly abraded with sand paper to simulate physical damage and artificially induce USB was higher in fruit held at 10 °C than at 6?8 °C or 12?13 °C for 6?8?days. Compared to non-affected skin, USB-affected tissue had a 7.4% increase in total phenolics concentration. However, polyphenol oxidase (PPO) and peroxidase (POD) activities decreased by 19%. Anatomical similarities were observed between USB symptoms and sapburn caused by spurt sap or terpinolene (a major sap component) to abraded skin areas. Incidence of sapburn was higher in abraded fruit held at 12 °C than at 20 °C. CONCLUSION Holding HG mango fruit at 10 °C can intensify USB. Activities of PPO and POD appear not to be regulatory factors in USB expression in HG. Sap components may be involved in USB expression under conducive postharvest conditions. ? 2021 Society of Chemical Industry.

Mesocarp bruising is an important postharvest problem of avocado fruit. Bruise expression may be influenced by inherent fruit characteristics, and pre- and postharvest handling practices and conditions. In this supply chain focused study, the putative effects on avocado cv. ‘Hass’ bruise expression and severity of fruit maturity, temporal duration before or after impact injury, fruit firmness, and fruit holding temperature were examined. Mesocarp bruising in ripening fruit decreased in a linear fashion with advancing fruit harvest maturity over 20 weeks. Bruise severity increased progressively in fruit kept for up to 5 weeks before impact injury and also for those kept for up to 7 days after injury. Hard green mature stage fruit did not express bruising at ≤100 cm drop height (∼1.36 J energy absorbed). However, softening, firm ripe, and soft ripe stage fruit impacted from 50 cm (∼0.8 J energy absorbed) developed progressively greater levels of bruising. Keeping fruit at temperatures of 2.5 °C and 5 °C as compared with 20 °C at the time of impact resulted in less bruise expression. Similarly, fruit kept at post-impact temperatures of 2.5 °C and 5 °C as compared with 7.5 °C, 10 °C, and 20 °C also resulted in less bruise expression. Fruit kept at 5 °C for the first 8 h after impact and then at 25 °C for 40 h developed less bruising than fruit kept at 25 °C for 8 h after impact and then at 5 °C for 40 h. Overall, it is proposed that harvesting fruit at ≥23% dry matter concentration, passing them quickly through the supply chain such that bruising has less time to express, and keeping the fruit ‘at’ or ‘below’ 5 °C in the supply chain could reduce bruise expression levels in ripening ‘Hass’ avocado fruit.

The mango cultivar 'Honey Gold' (HG) was developed in Queensland, Australia. Ripe defect-free HG fruit are characterized by bright yellow skin with red blush on their sun-exposed shoulders. HG mangoes are mostly grown from the Northern Territory down though Queensland into northern New South Wales (nNSW). As with many mango cultivars, HG suffers from a range of skin disorders. However, HG mango fruit grown in nNSW almost uniquely express a blotchy 'skin reddening' disorder that detracts from their visual appeal. The non-uniform reddening, which can encompass 'red lenticels', appears to be a host defense response. Causal agents of the reddening disorder are currently elusive. There may be a range of pre- and postharvest abiotic and/or biotic stresses, and they could be additive. A number of physical and chemical treatments were applied pre- or postharvest with a view to either suppress (i.e., prevent) or enhance (i.e., mask) uneven skin reddening. The physical treatments included preharvest fruit bagging and post-harvest exposure to different wavelengths of light. These physical treatments are considered in this paper. The chemical treatments included known modulators of host defense and ethylene responses. Those treatments are not reported in this short paper. However, among the full suite of treatments tested, one only notably influenced skin reddening. In this case, postharvest exposure to blue light increased reddening. Future research with HG will build on this initially promising finding.

Lenticel discoloration (LD), under-skin browning (USB) and resin canal disorder (RCD) are three important fruit skin disorders of concern to the Australian mango industry. They result in downgrading of fruit quality and loss of market confidence. LD is confined to the discoloration of lenticels on the fruit skin. USB is a sub-surface spreading grey-brown lesion that may only become evident in the marketplace. RCD is a dark brown discoloration of the finely branched pattern of ramifying sub-surface resin canals. These three browning disorders were compared and contrasted at the cellular level by light microscopy after free-hand sectioning. Discoloured lenticels on the surface of 'Honey Gold' mango fruit typically appeared as small round spots comprised of a dark brown centre surrounded by a white corona. Non-coloured lenticels were visible as small round spots surrounded by a white corona. In cross-section, there was browning of cells surrounding the cavity of discoloured lenticels. Nonetheless, there was no such browning in non-coloured lenticels. USB symptoms in 'Honey Gold' fruit were evident as dark-brown cells in the tissue surrounding the resin ducts. In contrast, RCD, which was evident in 'Kensington Pride' mango fruit, was characterised by browning of the lumen of resin ducts. Accordingly, LD, USB and RCD involve different browning biology processes at the cell and tissue levels. A greater understanding of symptom development and expression could aid in informed management of these physiological disorders.

Refrigerated containers are used to transport mangoes over long distances. In Australia, mangoes grown in northern tropical production areas for the domestic market are transported by road and/or rail for up to 4000 km to southern ripening centres. There is no other viable option for growers to ripen their fruit. A current project is investigating sustained ethylene release systems for ripening mango fruit in road transport containers over an in-transit period of up to 4 days. This approach could potentially provide an alternative cost-effective ripening strategy for the mango industry. Studies have been and will be performed using shipments of 'B74' and 'Honey Gold' mango fruit, respectively, in refrigerated road containers. In-container environment monitoring, fruit shelf life and quality evaluation at outturn are carried out. Corresponding laboratory experiments that simulate transit are also to be conducted with a view to modelling mango fruit responses to in-transit conditions.

Pakistan is one of the major mango-producing and -exporting countries in the world. During 2007-15, significant postharvest research and development (R&D) work was conducted under the Australian-funded ASLP mango supply chain management/value chain improvement projects (two phases). The project started by laying a postharvest foundation R&D infrastructure in 2007. Fruit quality losses in supply chains were documented. Protocols were developed for maturity testing, de-sapping, storage/sea-freighting, and ripening and postharvest disease management of major mango cultivars. Quantity loss (unmarketable fruit) was around 20% while quality loss (affecting price) was 65 and 70% in Sindhri and Samar Bahisht Chaunsa mango, respectively. Sap burn and postharvest diseases were the most important fruit quality issues at retail. Cultivars differed in terms of fruit harvest maturity indicators, postharvest treatment response, controlled atmosphere conditions and temperatures for storage and ripening. Besides physical de-sapping (on racks), lime wash (de-stemming and dipping fruit in 0.5% lime solution for 2-3 min) was also found to be effective, with morning being the best time for fruit picking. Significant relationships of production locality, orchard management, nutrition (Ca, B and K) and pre-cooling were found with postharvest disease incidence. Postharvest hot-water fungicidal dip of Scholar (active ingredient (a.i.) fludioxonil), Amistar (a.i. azoxystrobin) and Sportak (a.i. procholaz) gave significant fruit disease control. An integrated approach of good production practices, right maturity, correct postharvest fungicidal treatments and pre-cooling was an effective strategy for reducing disease incidence and maintaining better shelf-life at retail. On the basis of R&D and interventions, significant improvement was brought to the local mango industry and export. Sindhri mangoes were sea-freighted commercially to the EU and UK with good fruit quality outturn and overall postharvest life of 40-45 days.

Resin canal discoloration (RCD) is a quality defect that reduces the visual appeal and marketability of mango fruit. Market reports of RCD have increased recently, particularly for 'Kensington Pride' fruit produced in the Northern Territory, Australia. Anecdotal observations by mango growers suggest that early fruit harvest maturity, rain before harvest and handling conditions may be associated with RCD. In the current study, we completed a series of preliminary experiments with 'Kensington Pride' fruit to characterise RCD symptom development and to identify potential contributing factors. RCD was seldom present in hard green-mature fruit at harvest. The defect was first visualised as lightly discoloured resin canals in partially ripe fruit. The severity of RCD symptoms steadily increased as fruit developed from firm-ripe to eating-ripe. The incidence of RCD was 42-52% higher for fruit picked early in the season at KLEINERDAN13% dry matter content (DMC) than for those harvested 2-4 weeks later at 15-17% DMC. Harvesting fruit within 12 h of a 14-mm rainfall event resulted in 45% higher RCD incidence than in fruit picked after 60 h of sustained dry weather. The incidence of RCD varied from 0 to 45% for fruit from nine orchards in the Northern Territory when harvested and ripened directly off the tree. RCD incidence was threefold higher in the same fruit that were exposed to commercial handling and interstate transport. Overall, these observations suggest that RCD is a complex disorder that occurs when field conditions result in sensitised fruit that may express the defect when exposed to postharvest handling practices.

Satellite imagery, Geographical Information Systems (GIS) and Google Earth were demonstrated as effective tools for tree auditing and for defining the spatial variability of tree condition across two commercial 'Hass' Avocado blocks in Childers, Australia. Using a classified normalised difference vegetation index (NDVI) map derived from a WorldView2 image captured on April 19th 2013, and then repeated May 29th 2014, three replicate trees within high, mid and low growth regions were selected from each block. The annual harvest of these trees was conducted on May 21st 2013 and May 7th 2014, along with measures of leaf fluorescence and SPAD. Fruit quality measures were also conducted post-harvest. Spectral information corresponding to each of the sampled tree canopies was extracted and used to derive a number of pigment and structural based vegetation indices. These indices were correlated against the measured fruit and tree parameters, resulting in strong correlations with average fruit weight (g) (R=0.86∗ ∗, P=0.0001, RMSE=14.7 g); % commercial yield (R=0.71∗ ∗, P=

Skin spotting (SS) on avocado fruit is evident as blackened areas of

The temporal passage of fruit through the supply chain and the selection of consumable fruit by shoppers depend primarily upon fruit firmness. Traditionally, fruit firmness measuring methods, like Effegi and conical probes, are relatively inefficient and destructive. Simple, accurate and non-damaging methods of measuring fruit firmness are ideally required to help assure eating quality to the consumer without fruit wastage. The firmness of 'Hass' avocado fruit at a range of ripening stages was measured with the various different firmness measuring techniques of the Sinclair iQ Firmness Tester (SIQFT), the Electronic Firmometer (EF), the Analogue Firmness Meter (AFM) and hand squeezing. Measurements were made by each method at different points on the same fruit. Destructive bruise assessment was performed 48 h later, thereby allowing sufficient time for fruit to express any bruising resulting from the act of firmness measurements. Non-linear relationships were determined between fruit firmness values measured with the different techniques. The adjusted R2 for the relationship between the SIQFT and the EF was 91.6%. For the SIQFT and the AFM, the adjusted R2 was 73.7%. It was 77.7% for the SIQFT and hand squeezing. A significantly (P

A novel ethylene-α-cyclodextrin (α-CD) inclusion complex (IC) powder was investigated to ripen Calypso mango fruit. Modulated release of ethylene gas from the IC powder was achieved by admixture with deliquescent salt CaCl2 at RHs of 75.5% and 93.6%. The IC powder was tested in the laboratory and for in-transit ripening of mango fruit over two seasons. In the laboratory experiment, ethylene gas started to release from the IC powder in 2 h and complete release was achieved in 24 h. Assessments of fruit colour and firmness showed that encapsulated ethylene and commercial grade ethylene from pressurised cylinder similarly shortened the ripening time to 9–10 days (after harvest) for treated fruit as compared with 15 days for untreated mango. Mango fruit treated in both ways with ethylene showed more uniform ripening than the control. For the in-transit ripening using the IC powder, ethylene was found to be between 4.9 and 10.5 μL L−1 in the headspace of the truck containers over 48 h. Mango fruit from the treated containers shortened the ripening time by 3–6 days as compared to the untreated control fruit. Thus, the safe and convenient IC powder has demonstrated promise for in-transit fruit ripening.

The fruit of certain mango cultivars (e.g., 'Honey Gold') can develop blush on their skin. Skin blush due to red pigmentation is from the accumulation of anthocyanins. Anthocyanin biosynthesis is related to environmental determinants, including light received by the fruit. It has been observed that mango skin blush varies with position in the tree canopy. However, little investigation into this spatial relationship has been conducted. The objective of this preliminary study was to describe a 'Honey Gold' mango tree by capturing its three-dimensional (3D) architecture. A light path tracing model QuasiMC was then used to predict light received by fruit. The use of this 3D model was to better understand the relationship between mango fruit skin blush and fruit position in the canopy. The digitised mango tree mimicked the real tree at a high level of detail. Observations on mango skin blush distribution supported the proposition that sunlight exposure is an absolute requirement for anthocyanin development. No blush development occurred on shaded skin. It was affirmed that 3D mapping could allow for virtual experiments. For example, for virtual canopy thinning (e.g., 'window pruning') to admit more sunlight with a view to improve fruit blush. Improvements to 3D modelling of mango skin blush could focus on increasing accuracy, e.g., measurement of leaf light reflectance and transmission and the inclusion of the effect shading by branches.

'Honey Gold' is an Australian mango cultivar with attractive skin colour and good flavour when ripe. Under-skin browning (USB) is a disorder that develops on 'Honey Gold' fruit after harvest. The disorder is usually not evident until fruit reach the wholesale market. Thus, fruit often need re-packing at the markets, causing considerable wastage and financial loss. Previous research suggested that USB results from an interaction between physical pressure (i.e., mechanical stress) and low temperature (i.e., physiological stress) during transport and distribution. To address this issue, fruit from three farms in the Northern Territory were either cooled to 13°C within 10 h of harvest, or held at 18-20°C for 1-2 days before cooling to 13°C. The fruit were packed within commercial fibreboard trays in either standard plastic liners, a 'softer' liner to potentially minimise fruit damage, or were individually wrapped in plastic or bubble wrap to prevent any damage. The fruit were then palletised and transported for three days to southern Australia in a refrigerated truck. Delaying cooling after harvest for two days reduced the incidence of USB by 52-85%. As compared to using standard liners and cooling immediately after harvest, the proportion of fruit with USB decreased from 25 to 3% when fruit packed with soft liners were held at 18-20°C for two days before cooling at 13°C and transporting. These findings show that reducing the risk of vibration damage by using soft liners in combination with a delay in temperature reduction after harvest can significantly reduce USB in commercial practice.

Skin colour is an important quality parameter that influences mango fruit marketability. The mango industry is interested in controlled induction of skin blush in mangoes. It is desirable to understand the control of anthocyanin accumulation in mango skin. Among environmental factors known to induce anthocyanin accumulation in plants, light is the most studied. Light exposure induces pigmentation in various fruits, including apple, strawberry and grape. The effect of different light qualities on skin blush in mango fruit has received relatively little attention. The objective of this study was to assess anthocyanin accumulation and blush in response to blue, red and far red light from light-emitting diodes (LEDs) as applied to harvested mango fruit skin during storage at 12°C. Except for red light, the other wavelengths induced anthocyanin accumulation and skin blush as compared to the dark control treatment. Anthocyanin concentration and a∗ values were highest in blue light exposed fruit skin. This wavelength enhanced phenylalanine ammonia lyase activity in the mango skin, which may be associated with increased pigmentation. LED light treatment did not affect other fruit quality parameters at 21 days of storage, including firmness, total soluble solids and titratable acidity. Overall, the findings suggest that postharvest treatment with blue light can induce skin blush in mango fruit, which potentially may enhance their commercial value.

γ-Irradiation doses of 0.5 (target) and 1.0 (high) kGy were applied as insect disinfestation treatments to 'Kensington Pride' mango fruit. The effects of these treatments on fruit physicochemical properties and aroma volatile production were investigated and compared to non-irradiated controls. There were no significant effects of the irradiation treatments on flesh total soluble solids content. However, the loss of green skin colour usually associated with fruit ripening was inhibited by irradiation at both 0.5 and 1.0 kGy by approximately 32 and 52%, respectively, relative to non-irradiated fruit. Fruit exposed to 0.5 and 1.0 kGy exhibited a 58 and 80% reduction in emission of a-terpinolene volatiles, respectively. Thus, γ-irradiation at 0.5 and 1.0 kGy can have an adverse effect on 'Kensington Pride' mango fruit aroma volatile production and skin colouration.

Lenticel discolouration (LD) is a common disorder of mango fruit around the world. It results in poor appearance and disappointment of consumers. LD is exacerbated by treatment of mango fruit with gamma irradiation for insect disinfestation. The issue is problematic on the relatively new mango cultivar 'B74' and may represent an oxidative browning process. With a view to reducing irradiationinduced LD on 'B74', postharvest wax (one and three layers; 75% carnauba wax) and antioxidant (100 mM ascorbic acid, 100 mM calcium chloride, 10, 50 and 100 mM calcium ascorbate) dip treatments were investigated. Treatment of green mature fruit with three layers of wax prior to exposure to 557 Gy gamma irradiation reduced LD by 40% relative to the non-waxed control. However, the fruit failed to ripen properly as evidenced by delayed skin colour change, retarded softening and increased skin browning as compared to the controls and fruit coated with one layer of wax. Treatment with one layer of wax did not reduce LD. Mechanistically, the responses suggest that air exchange plays a pivotal role in LD. A lowered oxygen concentration in the lenticels may reduce the disorder after irradiation treatment. Postharvest treatments with the various antioxidants failed to reduce LD. Rather, all antioxidant treatments at the test concentrations, except calcium chloride, significantly increased skin browning.

'B74' mango fruit are sensitive to lenticel discolouration (LD). Exposure of the fruit to water during production and postharvest handling can increase LD. We propose that water infiltration into the lenticel cavity increases turgor in adjacent cells that leads to tissue strain, cellular stress and defence, and enzymatic browning. In the current study, we tested the efficacy of pre-harvest fruit bagging and coating treatments to reduce water infiltration and LD. Individual fruit on 'B74' trees at a commercial orchard were covered with a white paper bag, or coated with either 5% RainGard™ (a cracking suppressant), or 5% Raynox® (a carnauba wax-based coating) at two months before harvest. RainGard™ and Raynox® were re-applied to fruit at one month and one day before harvest. Additional fruit were coated with 2.5% Natural Shine™ TFC210 (a carnauba wax-based coating) at one day before harvest. The fruit were harvested, dipped in a detergent and a fungicide, and brushed. They were exposed to 10 μL L-1 ethylene at 20°C and allowed to ripen. The result showed that bagging and coating with Natural Shine™ TFC210 were the most effective treatments. They reduced LD on 'B74' fruit by 30-55% and 39-43% at the green mature and full ripe colour stages, respectively, as compared to the non-bagged and non-coated control. Pre-harvest bagging and coating treatments did not affect fruit firmness and lenticel morphology.

A novel ethylene-α-cyclodextrin inclusion complex powder was produced and tested for ripening 'Calypso' mango fruit. Ethylene was released from the powder under controlled humidity and temperature. Admixture with deliquescent calcium chloride (CaCl2) salt gave fast release of ethylene gas over 24 h. Ethylene gas released from the powder triggered mango ripening ascertained as fruit firmness and colour changes in a temporal manner similar to as for conventional ethylene gassing as compared to non-ethylene treated control fruit. The novel powder formulation has demonstrated promise for commercial application to ripen mango fruit.

Significant interactions have been demonstrated between production factors and postharvest quality of fresh fruit. Accordingly, there is an attendant need for adaptive postharvest actions to modulate preharvest effects. The most significant preharvest effects appear to be mediated through mineral nutrition influences on the physical characteristics of fruit. Examples of specific influencers include fertilisers, water availability, rootstock, and crop load effects on fruit quality attributes such as skin colour, susceptibility to diseases and physiological disorders, and fruit nutritional composition. Also, rainfall before and during harvest can markedly affect fruit susceptibility to skin blemishes, physical damage, and diseases. Knowledge of preharvest-postharvest interactions can help determine the basis for variability in postharvest performance and thereby allow refinement of postharvest practices to minimise quality loss after harvest. This knowledge can be utilised in predictive management systems. Such systems can benefit from characterisation of fruit nutritional status, particularly minerals, several months before and/or at harvest to allow informed decisions on postharvest handling and marketing options. Other examples of proactive management practices include adjusting harvesting and packing systems to account for rainfall effects before and/or during harvest. Improved understanding of preharvest-postharvest interactions is contributing to the delivery of consistently higher quality of fruit to consumers. This paper focuses on the state of knowledge for sub-tropical and tropical fruits, in particular avocado and mango.

Reported herein is a high throughput method to quantify in a single analysis the key volatiles that contribute to the aroma of commercially significant mango cultivars grown in Australia. The method constitutes stable isotope dilution analysis (SIDA) in conjunction with headspace (HS) solid-phase microextraction (SPME) coupled with gas-chromatography mass spectrometry (GCMS). Deuterium labelled analogues of the target analytes were either purchased commercially or synthesised for use as internal standards. Seven volatiles, hexanal, 3-carene, α-terpinene, p-cymene, limonene, α-terpinolene and ethyl octanoate, were targeted. The resulting calibration functions had determination coefficients (R2) ranging from 0.93775 to 0.99741. High recovery efficiencies for spiked mango samples were also achieved. The method was applied to identify the key aroma volatile compounds produced by ‘Kensington Pride’ and ‘B74’ mango fruit and by ‘Honey Gold’ mango sap. This method represents a marked improvement over current methods for detecting and measuring concentrations of mango fruit and sap volatiles.

BACKGROUND: The inability to consistently guarantee internal quality of horticulture produce is of major importance to the primary producer, marketers and ultimately the consumer. Currently, commercial avocado maturity estimation is based on the destructive assessment of percentage dry matter (%DM), and sometimes percentage oil, both of which are highly correlated with maturity. In this study the utility of Fourier transform (FT) near-infrared spectroscopy (NIRS) was investigated for the first time as a non-invasive technique for estimating %DM of whole intact 'Hass' avocado fruit. Partial least squares regression models were developed from the diffuse reflectance spectra to predict %DM, taking into account effects of intra-seasonal variation and orchard conditions. RESULTS: It was found that combining three harvests (early, mid and late) from a single farm in the major production district of central Queensland yielded a predictive model for %DM with a coefficient of determination for the validation set of 0.76 and a root mean square error of prediction of 1.53% for DM in the range 19.4-34.2%. CONCLUSION: The results of the study indicate the potential of FT-NIRS in diffuse reflectance mode to non-invasively predict %DM of whole 'Hass' avocado fruit. When the FT-NIRS system was assessed on whole avocados, the results compared favourably against data from other NIRS systems identified in the literature that have been used in research applications on avocados.

Insights into the relative importance of various aspects of product quality can be provided through quantitative analysis of consumer preference and choice of fruit. In this study, methods previously used to establish taste preferences for kiwifruit (Harker et al., 2008) and conjoint approaches were used to determine the influence of three key aspects of avocado quality on consumer liking and willingness to purchase fruit: dry matter percentage (DM), level of ripeness (firmness) and internal defects (bruising). One hundred and seven consumers tasted avocados with a range of DM levels from ~20% (minimally mature) to nearly 40% (very mature), and at a range of fruit firmness (ripeness) stages (firm-ripe to soft-ripe). Responses to bruising, a common quality defect in fruit obtained from the retail shelf, were examined using a conjoint approach in which consumers were presented with photographs showing fruit affected by damage of varying severity. In terms of DM, consumers showed a progressive increase in liking and intent to buy avocados as the DM increased. In terms of ripeness, liking and purchase intent was higher in avocados that had softened to a firmness of 6.5 N or below (hand-rating 5). For internal defects, conjoint analysis revealed that price, level of bruising and incidence of bruising all significantly lowered consumers' future purchase decision, but the latter two factors had a greater impact than price. These results indicate the usefulness of the methodology, and also provide realistic targets for Hass avocado quality on the retail shelf.

Previous investigations with 1-methylcyclopropene (1-MCP) on avocado (Persea americana Mill.) fruit have focussed mainly on improving storage life by reducing the severity of disorders causing discolouration of the flesh. Development of 1-MCP and ethylene treatments, which also help control the time to reach the eating ripe stage, may confer additional practical benefits. In this context, the current study investigated the potential of 1-MCP to accurately manipulate ripening of non-stored 'Hass' avocado fruit by treatment before or after ethylene and at different times during ripening. To investigate this, 500 nL L-1 1-MCP was applied within 1 day after harvest, followed by ethylene 0-14 days after 1-MCP. In addition, fruit were treated with ethylene, then 1-MCP 0-8 days after ethylene. Treatment of fruit with 500 nL L-1 1-MCP for 18 h at 20 degreesC provided the maximum effect by increasing the days from harvest to ripe (DTR) from 8 (with no 1-MCP) to 20. Fruit treated with 500 nL L-1 1-MCP for 18 h at 20 degreesC remained insensitive to 100 muL L-1 ethylene applied between 0 and 14 days after 1-MCP for 24 h at 20 degreesC. Ripening of fruit exposed to 100 muL L-1 ethylene for 24 h at 20 degreesC could be delayed by up to 3.3 days by applying 500 nL L-1 1-MCP for 18 h at 20 degreesC up to 2 days after ethylene treatment. However, once the fruit started to soften (sprung) there was little effect of 1-MCP on DTR, compared with no 1-MCP. 1-MCP treatment was associated with increased severity of body rots (caused mainly by Colletotrichum spp.) and stem-end rots (caused mainly by Dothiorella spp.), which was likely due to the increased DTR in these treatments. Significant differences in disease severity were found between orchards (replications), with replicates with low disease severity being less affected by 1-MCP treatment. These results indicate that 1-MCP can delay ripening, but careful sourcing of fruit is required to reduce the risk of diseases in ripe fruit. There is some capacity to delay ripening using 1-MCP after ethylene. There is little potential to control ripening using ethylene after treatment with 500 nL L-1 1-1-MCP, but lower concentrations may be more effective. (C) 2004 Elsevier B.V. All rights reserved.

The potential for hot water treatment (HWT) to improve quality of ‘Hass’ avocado following cold disinfestation for fruit flies, was investigated. Avocado fruit were placed in water at 38–42 °C for 20–60 min, disinfested for 16 days at 1 °C, then ripened at 20 °C. In the following season, fruit from another orchard were treated with hot water at 39–42 °C for 20–30 min, disinfested as above, then ripened at 16 °C. In both seasons, HWT significantly reduced skin damage caused by cold disinfestation, with 40 °C for 30 min, 41 °C for 20–30 min and 42 °C for 25–30 min giving the greatest reduction. Hot water treatments also reduced body rots in ripe fruit, with 40 and 41 °C for 30 min being consistently the most effective. Treatment at 42 °C increased body rots compared to the other HWTs in one season, and there was no benefit of HWT times longer than 30 min. The severity of vascular browning (VB) and mesocarp discolouration (MD) in ripe fruit was generally low, and increased following cold disinfestation. Hot water treatments reduced VB severity but had no effect on MD. Treatment at 41 °C for 25–30 min and 42 °C for 25 min increased the percentage of externally acceptable fruit (less than 5% of the skin area with defects) from 0 to about 80% 3 days after removal from disinfestation. The same treatment also increased the percentage of ripe fruit with acceptable flesh quality (less than 5% of the flesh with rots or disorders) from 0 to 16–20%, due mainly to reduced body rots. These results indicate the commercial potential of HWTs of about 41 °C for 25–30 min, or 42 °C for 25 min to improve avocado external and internal fruit quality following cold disinfestation.

To investigate the variation in quality of 'Hass' avocado fruit within an orchard, fruit were harvested at commercial maturity from 15 'Hass' trees of similar appearance, growing in three adjacent rows on the same soil type, and receiving similar management. Fruit were harvested at commercial maturity, and either ripened at 22 degreesC or stored at 2 or 7 degreesC for 3 or 5 weeks and then ripened. Significant positive correlations (based, on the mean for each datum tree) were noted between fruit flesh calcium (Ca) and magnesium (Mg) concentrations and the (Ca + Mg)/potassium ratio, and the number of days for the fruit to reach the eating ripe stage (DTR). Negative correlations were also observed between these minerals and anthracnose and mesocarp discolouration (MD) severity. Negative correlations were observed between fruit potassium (K) and phosphorus (P) concentrations and DTR. Fruit from trees with high fruit yield were generally smaller, with lower anthracnose and MD severity, ripened more slowly, and had higher flesh Ca concentrations. It is likely that cultural practices that maintain moderate to high fruit yield and reduce variation in yield will improve avocado fruit quality and reduce variability in quality. Since the main differences between adjacent trees in this trial were the seedling rootstocks of unknown origin, it is suggested that rootstocks can have a significant impact on avocado yield and fruit quality. (C) 2002 Elsevier Science B.V. All rights reserved.

SummaryThe accuracy of the avocado dry-matter maturity index may be influenced by fruit sampling procedures. This research investigated the effects of avocado (Persea americana Mill; cv. Hass) fruit location in the tree, fruit size, the presence of damage on the fruit, and of holding fruit after harvest at differing relative humidities (r.h.), on the fruit percentage dry matter (DM) and quality. Fruit aspect in the canopy had no effect on the percentage DM or days to ripeness (DTR) in this trial, although fruit from the eastern side of the tree were larger. Smaller fruit and damaged fruit had higher percentage DM and ripened more quickly, suggesting that they were more mature. Damaged fruit (with ring neck or sunburn) were also smaller. Holding fruit at 60% r.h. or lower for 4.d increased the percentage DM of the fruit after the holding period by almost 1.5%, and reduced the DTR, compared with storage at 98% r.h. There were significant differences in the average fruit percentage DM and DTR between trees, ...

The effect of bagging of mango (Mangifera indica) fruit was evaluated in order to improve fruit quality of late maturing cultivars. In 1993/1994, fruit of the `Keitt' cultivar were bagged with white paper bags at approximately 100 days before harvest on two separate orchards in the same growing district. In 1994/1995, `Keitt' fruit from another growing district were bagged at 131, 105, 82, 56 and 31 days before harvest. Fruit were harvested when mature and the fruit quality assessed following ripening at 22°C. Anthracnose and stem end rot (SER), caused by Colletotrichum and Dothoriella spp., respectively, were reduced by bagging in both years. In 1994/1995, SER severity continued to decline with increasing bagging duration, but there was no further consistent reduction in anthracnose severity with bagging durations longer than 56 days. All bagging treatments increased the percentage of the skin area with yellow colour at the eating soft stage. The percentage of the skin with red colour, and its intensity, decreased with increasing duration of bagging. Fruit calcium concentrations were reduced by bagging for 56 days or less in the 1994/1995 trial, but not by longer bagging times (82–131 days). Percent dry matter (% DM) was higher, and days to ripen shorter, in bagged fruit from one orchard during 1993/1994. Fruit mass, flesh colour, total soluble solids, acidity and eating quality were generally not affected by bagging. These results indicate that bagging can improve fruit quality through reduction in disease, and this benefit outweighs the negative effects of bagging on skin colour in the `Keitt' cultivar.

A simple and relatively inexpensive laboratory-scale method for simultaneously producing 36 different atmospheres for controlled atmosphere experiments is described. Capillary bore glass tubing (15–50 mm long, 0.1–0.8 mm I.D.) is used to regulate gas flows, while gas compositions are varied by altering the length and I.D. of the capillaries. Improved approaches to head pressure maintenance and calculation of capillary bore and length have provided a reliable and robust system which is easy to construct and maintain. The standard system uses N 2 from a membrane separator unit (typically producing 98% N 2 ), air, and CO 2 to generate a matrix of 36 atmospheres (any six O 2 by six CO 2 concentrations, in N 2 ) at flow rates of up to 300 ml min −1 per channel. Humidity is controlled through selective passage of the gases through water. Pure O 2 is used only when high CO 2 or O 2 concentrations (greater than 15%) are desired. No adjustments to the system are required during operation, and fluctuations in composition are within experimental tolerance. Running costs are low when used with an N 2 separator, as only bottled CO 2 is required.

This chapter provides updated information on avocado fruit quality parameters, sensory perception and maturity, production and postharvest factors affecting quality defects, disinfestation and storage (including pre-conditioning), predicting outturn quality and processing.

This chapter reviews the technology and quarantine treatments that have been developed for the postharvest handling of mangoes. The following aspects are covered: considerations influencing postharvest requirements (market and consumer research, quality assurance and good agricultural practice); preharvest management (maturity, adjusting maturation time, skin colour and lenticel damage, storage life and physiological disorders, pests and diseases, weather conditions, and flavour and aroma); harvesting and transport to the packhouse (timing, sapburn, harvesting and desapping, and transport to the packhouse); packhouse measures (delivery inspection and traceability, desapping and washing, disease control, brushing, grading and sizing, grade standards, and disinfestation); preparing fruit for the market (surface coatings, packaging, inspection, palletizing, precooling, and ethylene and ripening); pre- and post-shipping storage (cold storage, and controlled and modified atmosphere storage); transport; and marketing (networks and cooperatives, promotion and consumer education).

Premature and rapid ripening are two ethylene-related postharvest problems of banana fruit. Ethylene binding inhibitors such as diazocyclopentadiene (DACP) delay fruit ripening, even when applied at late stages [2]. However, constraints prohibit commercial use of DACP [2]. 1-Methylcyclopropene (1-MCP), an alternative and irreversible ethylene binding inhibitor, prevents fruit ripening [1]. This study investigated effects of 1-MCP applied before or after ethylene gasing.

The potential to use percentage of dry matter (DM) and/or oil of the flesh of `Hass' avocado as a maturity standard to determine the latest harvest for acceptable fruit quality, was investigated. `Hass' avocado fruit were harvested from early October to mid-January from a commercial orchard in subtropical Queensland. The percentage of DM and oil changed little during the harvest period, and the eating quality of the flesh remained high. However, the incidence of body rots (caused mainly by Colletotrichum sp.) and the flesh disorders grey pulp and vascular browning, increased with harvest. These results indicate that percentage of DM and oil are not reliable late-maturity standards because of the inconsistent change with later harvests, and that disease and internal disorders can be the main determinants of latest acceptable harvest, rather than eating quality.

Postharvest longevity of some cut flowers is shortened by exposure to ethylene gas. Adverse effects of ethylene may be prevented by treatment with 1-methylcyclopropene (1-MCP) gas. Responses of 14 different native Australian cut flowers to 1-MCP and ethylene applied at concentrations of 10 nL·L-1 and 10 μL·L-1, respectively, were examined. Each gas was applied alone for 12 hours at 20 °C and they were also applied in series. Vase lives of Ceratopetalum gummiferum, Chamelaucium uncinatum, Grevillea `Kay Williams' and `Misty Pink', Leptospermum petersonii, Telopea `Shady Lady', and Verticordia nitens were reduced by ethylene treatment. Treatment with 1-MCP generally protected these cut flowers against subsequent exposure to ethylene. The 1-MCP treatment usually did not extend their vase lives in the absence of exogenous ethylene.

The potential for the ethylene binding inhibitor, 1-methylcyclopropene, to delay ripening of ‘Hass’ avocado, ‘African Pride’ custard apple, ‘Kensington Pride’ mango and ‘Solo’ papaya was examined. Fruit were gassed with 25 µL/L 1-methylcyclopropene for 14 h at 20°C, followed by treatment with 100 µL/L ethylene for 24 h, and then ripened at 20°C. Ethylene treatment alone generally halved the number of days for fruit to reach the ripe stage, compared with untreated fruit. 1-Methylcyclopropene treatment alone increased the number of days to ripening by 4.4 days (40% increase), 3.4 days (58%), 5.1 days (37%) and 15.6 days (325%) for avocado, custard apple, mango and papaya, respectively, compared with untreated fruit. Applying 1-methylcyclopropene to the fruit before ethylene prevented the accelerated ripening normally associated with ethylene treatment, so that the number of days to ripening for fruit treated with 1-methylcyclopropene plus ethylene was similar to the number of days to ripening for fruit treated with 1-methylcyclopropene alone. 1-Methylcyclopropene treatment was associated with slightly higher severity of external blemishes in papaya and custard apple, slightly higher rots severity in avocado, custard apple and papaya, and at least double the severity of stem rots in mango, relative to fruit not treated with 1-methylcyclopropene. Thus, 1-methylcyclopropene treatment has the potential to reduce the risk of premature ripening of avocado, custard apple, mango and papaya fruit due to accidental exposure to ethylene. However, additional precautions may be necessary to reduce disease severity associated with 1-methylcyclopropene treatment.

Premature ripening and/or senescence and abscission induced by exposure to ethylene are significant postharvest problems. Banana fruit and grevillea and Geraldton waxflower flowers are among affected commodities. Treatment with 1-methylcyclopropene gas or silver thiosulfate liquid can be used to prevent ethylene perception and response. Treatment of banana fruit with 10 nL 1-methylcyclopropene/L for 12 h at 20 degrees C afforded protection against subsequent serial treatments over 13 days of subsets with 100 mu L ethylene/L for 24 h at 20 degrees C. Protection of Grevillea 'Sylvia' inflorescences was effective only for 2 days. Thereafter, fruit and inflorescences regained sensitivity to ethylene. In contrast, neither banana fruit nor grevillea inflorescences treated with 10 nL 1-methylcyclopropene/L for 12 h at 2 degrees C were protected against ethylene. 1-Methylcyclopropene binding to ethylene receptors was apparently not achieved at the lower temperature. Increasing the 1-methylcyclopropene concentration to 100 nL/L, applied at 2.5 degrees C to banana fruit, achieved protection against ethylene. Waxflower sprigs treated with 10 nL 1-methylcyclopropene/L for 12 h at 2 or 20 degrees C regained full sensitivity to ethylene after about 2 and 4 days, respectively. In contrast, pulsing waxflower with 0.5 mmol Ag+/L as silver thiosulfate for 12 h at 2 or 20 degrees C afforded protection against ethylene for the 10 days duration of the experiment.

Summary. Treatment of cut flowering Boronia heterophylla (red boronia) stems with 10 L ethylene/L for 72 h at 20°C induced flower senescence and abscission, and thereby reduced stem fresh weight and vase life. Pre-treatment with 1-methylcyclopropene (1-MCP) reduced these ethylene effects. Treatment of B. heterophylla with 10 L ethylene/L for a shorter 12 h period at 20°C did not affect vase life. Rates of endogenous ethylene production by B. heterophylla flowers increased in association with wilting during flower senescence.

Bagging mango fruit during their development on the tree can reduce insect and disease damage. However, it is also possible that bagging can interfere with transpiration and associated calcium accumulation. Low calcium concentrations have been correlated with poor mango fruit quality. This study was conducted to evaluate the influence of bagging at various stages of fruit development on calcium concentration and postharvest quality of ‘Kensington Pride’ mangoes. Fruits were bagged at 41, 25 or 9 days before harvest. No statistically significant differences in either skin or flesh calcium concentration were found between the bagged (plastic or paper) and unbagged fruits. Postharvest weight loss was enhanced and shelf life reduced in the ‘plastic bagged’ fruits. In an ancillary study, calcium concentrations in ‘Kensington Pride’ nubbins (seedless fruit) were compared with those in seeded fruit, since it has been shown with apple fruit that greater seededness is positively correlated with increased flesh calcium concentrations. Conversely, however, calcium concentrations in the flesh of mango nubbins were found to be significantly higher (0.80 mg/g dry weight) than those in seeded fruit (0.58 mg/g dry weight) of similar size.

The potential for low temperature conditioning (LTC) treatments, either alone or in combination with hot water treatment (HWT), to improve the quality of ‘Hass’ avocado ( Persea americana Mill.) fruit following cold disinfestation of Queensland fruit flies, was investigated. Avocado fruit were held at 4–8 °C for 3–4 days then disinfested for 16 days at 1 °C before ripening at 16 °C. In a second experiment, fruit were placed in water at 41–42 °C for 15–25 min, either with or without LTC, then disinfested and ripened. In both experiments, LTC at 4 °C for 4 days or at 6–8 °C for 3–4 days increased the percentage of fruit with acceptable external appearance (less than 5% of the fruit with discrete dark patches on the skin, and skin spotting combined) after disinfestation from 0 to 100% due to the effective elimination of discrete patches on the skin. Disinfestation alone increased body rots and diffuse flesh discolouration severity in ripe fruit, while LTC before disinfestation reduced severity of these disorders to similar levels as those in non-disinfested, non-stored fruit. LTC before disinfestation reduced discrete patches severity and improved flesh quality more than HWT. Combined treatments of HWT and LTC before disinfestation were no more beneficial compared with LTC alone. Conditioning of fruit at 6 °C for 3 days followed by disinfestation resulted in no survivors from 50 748 third instars of Queensland fruit fly ( Bactrocera tryoni Froggatt). LTC efficacy was verified commercially by conditioning fruit at 6 °C for 3 days followed by disinfestation and airfreight to New Zealand. External fruit appearance and internal ripe fruit quality after disinfestation were found to be high. These results show that LTC before cold disinfestation effectively eliminates skin damage and improves flesh quality of ripe ‘Hass’ avocado fruit, with no negative effect on Queensland fruit fly disinfestation efficacy.