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Mature green ‘FL 47′ tomatoes were exposed to heat (52 °C water for 5 min) and/or cold (5 °C for 4 d) before sampling at following ripening stages. Results showed that although did not cause visual injury, chilling substantially suppressed ripening process, ethylene production and respiration rate at early stages, while a slight impact was observed by heating. Most volatiles were detected at low levels before breaker stage with a burst at red stage in all treatments. Chilling and heating induced production of “green” note volatiles, especially hexenal early in fruit development. At the red stage, 11 out of 12 important aromatic volatiles exhibited significant reduction in chilled fruit compared to control, while most volatiles in heated fruit were recovered during ripening. On the other hand, a pre-chilling heat treatment alleviated the chilling-caused reduction of ethylene during ripening, which was associated with higher levels of 6-methyl-5-hepten-2-one, 2-phenylacetaldehyde, and 2-phenylethanol in red fruit.

With a growing worldwide population, feeding 10 billion people by the year 2050 is the next global challenge. Fresh produce systems account for a significant fraction of total food and resource consumption due to their perishable nature, with postharvest quality being a key challenge. Production models for fresh produce are widely used and well adapted, whereas postharvest operations (PO) models have only recently been developed. The overarching goal is to quantify interactions of food quality, water and energy use in PO. In this study, an existing PO model was enhanced and implemented for a field grown tomato operation in Florida. Model estimates were compared with data from a representative operation, and were upscaled to obtain statewide estimates. The enhanced model was found to be the most sensitive to harvest frequency, quantity shipped to customer, and quantity harvested. At maximum grower profit, the model estimated water and energy quantities roughly 20% lower for each operation. The representative operation exceeded optimal water and energy usage because the farmers, despite having efficient production, commonly ”over-produce” far beyond optimal levels for reasons including risk of loss, tradition, low market prices, and large fixed costs of operation. Postharvest loss estimated by the model was 22% of quantity harvested for the representative operation. The upscaled regional postharvest losses were at 16% for the state of Florida. Operation-specific water and energy use from the case study were upscaled to give regional monthly estimates of 50.3 million liters and 28.3 million kWh, respectively. Such interactions provide insights into postharvest decisions made by commercial operations and impacts of these decisions on the food, water and energy system. The integrated modeling framework in this study can be extended to other crops and quantify interactions of water, energy and, postharvest losses to optimize efficient management practices.

We used genomic tools to understand senescence and molecular signaling events in harvested broccoli florets stored at 25 or 4 °C to test the hypothesis that genetic markers can be used to identify the stage of senescence or physiological age of plant tissue. The RNA-sequencing approach provided key insights into the gradual changes in transcriptome during postharvest storage in broccoli. We found that 4279 and 4143 transcripts were differentially expressed after 3 and 5 days of storage at the two storage temperatures, respectively. We then performed genome-wide comparisons at 25 and 4 °C and illustrated the temporal and spatial-specific genes in stored broccoli. By using quantitative Real-Time PCR and transient tobacco assay, we validated our RNA-sequencing experiment. We further performed comparative analysis of Arabidopsis and broccoli to disclose conserved senescence genes. Concurrently, we found that 43 genes were senescence-specific genes that are common senescence-associated genes (SAGs) regardless of tissue-specific expression. Interestingly, we observed 73 transcription factors (TFs) within this group that might form a core transcriptional regulatory circuitry to control the onset and progression of senescence. Moreover, we also identified new molecular players involved in postharvest senescence including brassinosteroids (BR) perception genes, BIK1 (Brassinosteroid-Interacting Kinase1), BRL1 (BRI1-like 1), BIR1 (BAK1-Inteacting Receptor-Like Kinase 1), stomatal patterning gene SPCH, and circadian clock genes CCA1. Those genes could serve as ‘freshness-indicators’ for the stage of senescence or relative freshness of the product. This report identified the SAGs that are essential for tissue-specific senescence and provided fundamental insights into signaling events during postharvest senescence in Brassica plants.

Improper postharvest handling often impairs horticultural quality even when damage is visually imperceptible. In this study, tomato fruit were subjected to controlled compressive forces (196.13 N) and the effects of this mechanical damage were evaluated. The following parameters were assessed: production of CO2, ethylene (C2H4), color, enzymatic activity (LOX, HPL and ADH) and volatile compounds. Ethylene production increased in tomatoes subjected to compression. Damaged tomatoes were unable to develop the typical red color when compared to the control fruit and showed a transient increase in the activity of the enzymes LOX, HPL and ADH. The imperceptible damage applied to tomatoes modified the profile of volatile compounds produced by the fruit, reducing the emission of compounds perceived as fruity and sweet.

Muscadine grape (Vitis rotundifolia Michx) is a non-climacteric fruit that rapidly loses quality during storage. This study aimed to assess the effect of controlled atmosphere (CA) on quality parameters and muscadine grapes decay. Berries of two muscadine grape cultivars, Triumph, and Supreme, were stored at 4 °C with 95 % relative humidity in either regular air (AIR), regular CA (RCA) (6 % O2 + 10 % CO2), or CA with extreme CO2 level (ECA; 4 % O2 + 30 % CO2) for up to 42 d. Treated berries with either RCA or ECA provided better control of weight loss. Both CA treatments reduced decay incidence, but there was no decay in ECA berries after 42 d for both cultivars and no evidence of CO2 injury. The results showed that berry softening was significantly delayed by RCA and ECA, which had a lower ethylene production rate than berries exposed to AIR. Application of RCA and ECA also retained greater total antioxidant activity, total phenolic compounds, and firmness compared to AIR. These results demonstrate that maintaining CA conditions postharvest leads to improved preservation of compositional quality and delayed softening and decay of harvested muscadine grapes compared with AIR storage.

Controlled postharvest stresses were used to induce the synthesis of antioxidants in tomato fruit. In this study, a hot-water (HW) treatment of 52 °C for 5 min promoted higher total oxygen radical absorbance capacity (ORAC) compared to fruit immersed in 25 °C water for 5 min. Whereas, ethylene treatment at high temperature, particularly at 35 °C for 24, 48 or 72 h, induced higher content of total phenolics and ferric reducing ability of plasma (FRAP) than fruit treated with ethylene at 20 or 30 °C. In combination, there was synergy between the treatments, and this was most notable by the increase of total phenolics in HW-treated tomatoes exposed to ethylene at 35 °C for 24, 48 or 72 h. There was also a significant increase of total ORAC in HW-treated fruit exposed to ethylene at 30 °C for 72 h or 35 °C for 24, 48 or 72 h. This increase in antioxidant capacity was observed in the hydrophilic fraction of HW-treated fruit exposed to ethylene at 30 °C for 72 h or 35 °C for 24 or 48 h and in the lipophilic fraction of HW-treated tomatoes exposed to ethylene at 35 °C for 24, 48 or 72 h. Moreover, The HW-treatment especially maintained the level of total carotenoids and ascorbic acid when exposed to ethylene at 30 °C for 72 h or 35 °C for 48 or 72 h. Nevertheless, the high temperature ethylene treatment reduced the a* value of tomato peel regardless of the application of HW treatment. In conclusion, application of a HW treatment of 52 °C for 5 min followed by exposure to ethylene at 35 °C for 48 h was most effective in synergistically improving the antioxidant capacity and composition of tomatoes without severely impairing color development.

The effects of 1­methylcyclopropene (1-MCP) treatment on the quality attributes of ‘Taoxingli’ plum fruit, particularly on whole fruit anthocyanin content via anthocyanin biosynthesis during storage at the non-chilling temperature of 10 °C were investigated. The results showed that 1-MCP treatment effectively reduced weight loss and better maintained soluble solids content (SSC) and titratable acidity (TA), resulting in increased contents of fructose, glucose, sorbitol, and malic acid, and reduced decay during storage. Furthermore, major anthocyanins, including cyanidin 3-O-glucoside and cyanidin 3-O-rutinoside, were detected. 1-MCP treatment delayed increases in total anthocyanins along with the major individual anthocyanins during storage, which was attributed to its effect in suppressing the expression of synthesis-related structural genes and the transcription factor PsMYB10 early in storage, enhancing their expression later in the storage period. Thus, 1-MCP treatment was beneficial for retaining the quality of ‘Taoxingli’ plums, particularly the chemical attributes, and extending the storage life with low economic loss during storage.

Plants are constantly exposed to abiotic and biotic stresses, inducing the generation of reactive oxygen species (ROS). In response, the synthesis of antioxidants is upregulated to neutralize the deteriorating effects of ROS. We investigated whether promoting this response could enhance the nutritional and sensory quality of tomatoes. In preliminary experiments, mature green tomatoes were immersed in hot water (HW) at 50 °C for 5 min, 52 °C for 5 min, or 54 °C for 2.5 min (25 °C water for 5 min as control); subsequent experiments utilized 52 °C for 5 min. Following those treatments, we evaluated the changes in color, texture, soluble solids, titratable acidity, and the antioxidant system of the fruit during ripening at 20 °C and 85–90 % relative humidity. The HW treatment of 52 °C for 5 min promoted higher accumulation of carotenoids and lipophilic phenolics, resulting in greater color development and slightly higher antioxidant potential, but did not otherwise affect the composition of ripe fruit; the tomatoes ripened normally after HW immersion, with no firmness differences, but were darker red and less yellow-orange with higher antioxidant potential. Furthermore, we observed that the beneficial effects were more noticeable at early stages of ripening, even in varieties that did not exhibit major differences after reaching full ripeness. In this sense, we found that ‘Florida 47’ and ‘Security 28’ tomatoes have a limited response to HW treatment compared with ‘Soraya’ and especially ‘Tasti Lee’ tomatoes, indicating that there might be genetic constraints on the response in the former varieties. The beneficial effect of immersing the tomatoes in HW was proportional to the heat penetration profile inside the fruit; for example, the 52 °C for 5 min treatment increased the temperature up to 45 °C in the peripheral tissues 4 mm below the fruit surface where the content of carotenoids and lipophilic phenolic compounds was mainly increased; whereas, the tissue temperature was 35 °C at the center of the tomato, where we did not observe any change in composition. In conclusion, the HW immersion used in this research promoted the synthesis of lipophilic antioxidants such as carotenoids in tomato fruit, enhancing red color development and antioxidant potential.

Previous reports showed that both gaseous and aqueous 1-methylcyclopropene (1-MCP) delay ripening of avocado ( Persea americana Mill.), but there are no reports of the influence of 1-MCP on its sensory attributes. The objective of this study was to evaluate the effects of ethylene pretreatment and/or exposure to gaseous or aqueous 1-MCP on fruit ripening and sensory attributes of ‘Booth 7’ avocado, a Guatemalan-West Indian hybrid. Separate experiments were conducted during two seasons (2008 and 2009) with fruit harvested at preclimacteric stage in October (early season) and in November (late season). Fruit from Season 1 were exposed to ethylene (4.07 μmol L −1 ) for 12 h at 20 °C, and stored for more 12 h at 20 °C in an ethylene-free (ethylene, −1 ) room prior to treatment with either aqueous (1.39 or 2.77 μmol L −1 a.i.) or gaseous (3.15 or 6.31 nmol L −1 a.i.) 1-MCP. Ripening was monitored and firmness, respiration, ethylene production and weight loss were measured. Texture profile analysis and sensory analysis were performed on ripe fruit only (firmness, 10–15 N). Fruit from Season 2 were not exposed to ethylene pretreatment but treated only with aqueous 1-MCP 24 h after harvest. Fruit were assessed exclusively for sensory analysis when ripe (firmness, 10–15 N). Treatment with either 1-MCP formulation effectively delayed ripening from 4 to 10 d for early-season fruit, and from 4 to 6 d for late-season fruit. Higher concentrations of 1-MCP of either formulation had the greatest effect on selected pulp textural parameters of early-season fruit; the gaseous formulation had greater effect on late-season fruit quality than the aqueous formulation. In general, sensory panelists ratings of overall liking were not affected by 1-MCP treatment. Both aqueous and gaseous 1-MCP formulations delayed ripening of the Guatemalan-West Indian ‘Booth 7’ avocado without significant loss in appearance or in sensory attributes and, therefore, could be considered for use as a postharvest treatment for this hybrid.

Long term low temperature storage of mature-green tomatoes is currently risky because of the likely development of chilling injury (CI), reducing shelf life and hence restricting flexibility of trade. Intermittent warming (IW) has been proposed as a potential solution to aid successful long term tomato storage. The effectiveness of an IW regime in reducing CI was tested in two different tomato cultivars each grown in a different production conditions (Palmerston North, New Zealand and FL, USA) and stored at low temperature. Three cycles of IW to 20 °C for 24 h every 7 d reduced CI and decay development in fruit stored at either 2.5 or 6 °C for 27 d. However, efficacy of IW differed greatly between the two cultivars/production regions. Cycles of IW enhanced red colour development in New Zealand greenhouse-grown ‘Cedrico’ tomatoes stored at 6 °C, while the same cycles in field-grown ‘Soraya’ tomatoes in Florida did not. Decay severity was higher in ‘Soraya’ and occurred at both 2.5 and 6 °C, whereas ‘Cedrico’ showed decay at only 2.5 °C. However, IW reduced decay incidence in tomatoes from both locations. While IW was effective in reducing CI in both cultivars/production regions, these results suggest that CI symptoms and IW efficacy are highly dependent on cultivar and/or production conditions.

Hexanal, Z-3-hexenal, E-2-hexenal, hexanol, and Z-3-hexenol are major tomato (Solanum lycopersicum L.) volatile aroma compounds derived from oxygenation of unsaturated fatty acids. Chilling and heating may suppress production of these C6 volatiles. The objective of this research was to determine the effects of chilling or heating on gene expression and enzyme activity of lipoxygenase (LOX), hydroperoxide lyase (HPL), and alcohol dehydrogenase (ADH), which catalyze key steps in C6 volatile production via the oxylipin pathway. ‘Tasti-Lee’ and ‘Sanibel’ tomatoes, harvested at different stages of fruit development, were ripened to full (red) ripe stage at 20 °C. Fruit were then treated by either chilling (5 °C for 5 d) or heating (52 °C hot water for 15 min), then cooled with 23 °C tap water to 25 °C and placed at 20 °C for 4 d, or held continuously at 20 °C as the control. Both chilling and heating reduced C6 aldehyde and alcohol aroma volatiles immediately after treatment, and the levels of aldehydes did not fully recover after 4 d at 20 °C. Chilling down-regulated expression of TomloxA, B, and C, but not D; however, it increased total LOX activity. Chilling also down-regulated HPL and ADH expression immediately after treatment, but, after 4 d at 20 °C, both genes were up-regulated compared to the control. HPL activity in chilled tomatoes was reduced, but recovered to control levels after 4 d at 20 °C. ADH activity in chilled fruit decreased after 4 d at 20 °C. On the other hand, heating greatly up-regulated TomloxB and C expression, even after 4 d at 20 °C, and slightly down-regulated TomloxA and D, while increasing overall LOX activity. Heating up-regulated both HPL and ADH, and that effect persisted for 4 d at 20 °C. However, heating reduced the activities of HPL for 4 d at 20 °C and ADH immediately after treatment. The results indicate that heating and chilling regulate C6 volatile production by different mechanisms. Chilling-induced inhibition of C6 volatile production may be due to down-regulation of gene expression, and subsequent reduction of HPL and ADH enzyme activities in the oxylipin pathway. Heating-inhibition of C6 volatile production, however, does not appear to be due to down-regulation of gene expression, but HPL and ADH activities were briefly suppressed.

This study addressed the effects of hot water (HW) quarantine treatment as mandated by the USDA-APHIS, for all mangoes imported to the United States, on the visual and compositional quality factors, aroma volatile production, respiration rate, and electrolyte leakage of fresh-cut ‘Kent’ mango slices during subsequent storage at 5 °C for 10 d. The experiment was conducted twice during two Florida mango seasons, with fruit from two different sources. Results from the two harvests were significantly different and therefore were analyzed separately. In general, the visual quality, electrolyte leakage, firmness, and aroma volatile production (based on the quantification of 16 aroma volatiles) did not differ between the fresh-cut slices prepared from HW- and non-HW-treated fruit. The fresh-cut slices from non-HW-treated fruit had higher soluble solids content than the HW-treated samples. There were also differences between the treatments for respiration rate, titratable acidity, and pH; but, the results were contradictory between the two harvests. Overall, the results suggest that the HW quarantine treatment applied to whole mangoes does not significantly affect the quality of fresh-cut ‘Kent’ mango slices stored at 5 °C.

To study the effects of storage atmosphere on the main quality attributes of minimally processed leeks, stalks were stored in air, 1, 3 or 5% O 2 in N 2 , 6, 11 or 17% CO 2 in air, or 1% O 2 + 14% CO 2 in N 2 at 6.5 °C for 14 days. In addition, other leeks were subjected to a preprocessing treatment consisting of exposure to air or 1% O 2 + 14% CO 2 at 6.5 °C for 0, 12, or 24 h prior to minimal processing and storage in air or 1% O 2 + 14% CO 2 at 6.5 °C for 14 days. Leaf and root growth, number of newly formed roots, color changes at the basal cut surface as well as on the white and green leaf tissue, fresh weight loss, and enzymatically produced pyruvic acid content were determined. Storage of minimally processed leek stalks in 1% O 2 at 6.5 °C for 14 days minimized leaf and root growth as well as color changes at the center of the basal cut surface, but did not prevent peripheral discoloration of the basal cut surface; the other reduced O 2 and elevated CO 2 treatments were less effective than 1% O 2 in reducing leaf and root growth and cut surface discoloration. Storage in 1% O 2 + 14% CO 2 , however, resulted in an additional beneficial effect compared with 1% O 2 alone by preventing the appearance of peripheral discoloration on the basal cut surface. Exposure to 1% O 2 + 14% CO 2 at 6.5 °C for 12 or 24 h prior to processing did not further contribute to quality maintenance of minimally processed leeks during storage in either air or 1% O 2 + 14% CO 2 at 6.5 °C for 14 days.

‘Rhapsody’ tomatoes were exposed to air at 20 (control), 34 or 38 ◦ C, and 95% RH for 24 h and then stored at 4 ◦ Co r 20 ◦ C for up to 4 weeks. Fruit exposed to 34 or 38 ◦ C and stored at 20 ◦ C had higher cysteine, “reduced glutathione”, catalase, and glutathione S-transferase, but lower isoascorbic acid and ascorbate peroxidase compared to control fruit. Fruit exposed to 38 ◦ C developed slight heat injury, and had slightly lower -carotene, lycopene, cysteine, ascorbate peroxidase, catalase, and “reduced glutathione” compared to fruit exposed to 34 ◦ C. Fruit stored at 4 ◦ C had less color development, lower -carotene, lycopene, ascorbic acid, isoascorbic acid, dehydroascorbic acid, cysteine and “reduced glutathione”, and higher -tocopherol, dehydroascorbate reductase, peroxidase, catalase, and glutathione reductase than those stored at 20 ◦ C. Of the two heat treatments, 34 ◦ C for 24 h caused little injury, and had less negative effects on antioxidants during storage at

The consequences of poor temperature management during air transport were investigated by storing intact, abraded, or abraded + inoculated (Colletotrichum gloeosporioides) papaya fruit (cv. Red Lady) for 76 h in three temperature regimes simulating different commercial air handling scenarios followed by storage for 7 days at 20 ◦ C to simulate shelf life. The papayas in two fluctuating temperature regimes deviated from a semi-constant regime by being held for 1 h at 15 ◦ C plus 1 h at 23.5 ◦ C versus 2 h at 12 ◦ C to simulate the period on the tarmac prior to loading onto an airplane, 7 h at 23.5 ◦ C versus 7 h at 12 ◦ C to simulate the flight period, and then for either 2 h at 1 ◦ C or 2 h at 23.5 ◦ C versus 2 h at 12 ◦ C to simulate waiting on the tarmac after unloading the airplane. The fluctuating temperature regimes simulated actual conditions previously documented by us as encountered during ground and in-flight perishable handling operations. Overall, papayas handled in the fluctuating cold or warm temperature regimes lost more weight, developed objectionable color, were softer and more shriveled, had more decay, and had lower soluble solids, acidity and ascorbic acid contents than papayas handled in the semi-constant temperature regime. In addition, papaya handled in the fluctuating cold temperature regime that included exposure to 1 ◦ C for 2 h developed chilling injury symptoms after being transferred to 20 ◦ C for 7 days. Abraded and abraded + inoculated papaya fruit handled in semi-constant temperature developed less decay during shelf life than those stored in fluctuating temperatures. Loss of firmness and development of chilling injury symptoms were the primary quality factors that limited the shelf life of papaya fruit. Papaya from the first harvest and handled in a semi-constant temperature regime never became unacceptable for sale even after 7 days of shelf life. For papayas transported in fluctuating cold or warm temperature regimes, the greatest quality loss was noticeable during simulated air flight, during truck transportation from the airport to the warehouse and then to the supermarket, and during shelf life compared with warehouse storage at the grower, truck transportation to the airport, waiting on the tarmac, or backroom storage at the supermarket. The results indicate that fluctuating and/or high or low temperatures that are often encountered for as little as a few hours during handling operations, may result in a considerable amount of papaya rejected.

The objective of this work was to elucidate the relationship between low pressure (LP) such as that found aboard cargo aircraft and the residual effect on stomatal aperture of Beit Alpha-type cucumbers during subsequent, simulated after-flight storage. In order to simulate flight conditions, cucumbers previously equilibrated to 4 ◦ C were stored in darkness for 6 h at 71 kPa, 20 ◦ C, and initial relative humidity (RH) of 70% in either airtight or non-airtight (air-flow rate of 0.415 L s −1 ) containers. Cucumbers in airtight and non-airtight containers at 101 kPa were used as controls. After the flight simulation, the fruit were transferred to 101 kPa cold rooms at 20 ◦ C and 70% RH or 7 ◦ C and 90% RH and stored in darkness for 7 days. Exposure of cucumbers to 71 kPa in either airtight or non-airtight containers increased moisture loss after-flight simulation, and throughout storage compared to 101 kPa. Most stomata were fully or partially open immediately after-flight simulation regardless of treatment, however, cucumbers from the LP treatments retained significantly more open stomata compared to their respective controls after 96 h of subsequent storage at 101 kPa. This suggests that cucumbers exposed to a LP of 71 kPa for only 6 h, may exhibit an indirect stress response that occurs only when the fruit are returned to 101 kPa, preventing stomatal closure. This residual effect may be explained by the possibility that LP enhances outward diffusion of CO2, reducing intercellular CO2 concentration (Ci), and causing stomata to open. When the fruit are transferred to 101 kPa, stomata may remain open to restore the Ci. © 2006 Published by Elsevier B.V.

This study was undertaken to optimize ethanol vapor application as a ripening inhibitor on whole mangoes to extend fresh-cut mango shelf life. Freshly harvested mangoes were first subjected to hot water (+HW) at 46 ◦ C for 60 or 90 min to simulate quarantine heat treatments, or remained untreated (−HW). Fruit of each batch (+ or −HW) were then held at 20–25 ◦ C for 4 or 7 d (D4 and D7) after the hot water treatment before being exposed to ethanol vapors [0 h (E0), 10 h (E10), or 20 h (E20)]. Fruit were then peeled and cut into slices, packed in plastic clamshells, and stored at 7 ◦ C for 15 d. Only slices from +HW-D4-E20-treated fruit maintained higher firmness, hue angle, and titratable acidity (TA) in storage. The +HW-D7-E10- or E20-treated fruit had higher hue angle than E0, but firmness, total soluble solids, TA, pH, and respiration rate did not differ. Internal ethanol and acetaldehyde were very high in slices from +HW, D4 and D7, E20 and −HW-D7-E20-treated fruit. A sensory panel could perceive higher firmness and acidity in slices from fruit treated with ethanol. However, E20 induced off-flavor, and these fruit were least preferred. Ethanol exposure on fruit was repeated with purchased mangoes that had been subjected to a commercial quarantine heat treatment. A second heat treatment of 18 h at 38 ◦ C and 98% relative humidity was added to one batch of fruit in this experiment. Ethanol vapors did not result in delayed ripening in those mangoes. However, this treatment inhibited microbial growth. The second heat treatment did not improve fresh-cut mango shelf life, and further, microbial growth increased compared to other treatments. It is concluded that, due to inconsistent results, ethanol vapor applied for 20 h to whole mangoes prior to processing for fresh-cut is not a practical approach to delay ripening; however, at lower doses (10 h), it could be used as a safe microbial control in a fresh-cut production sanitation system. Published by Elsevier B.V.

Respiration rate, sensory attributes, colour alterations, and water, chlorophyll and ascorbic acid contents were monitored during storage of shredded Galega kale (Brassica oleracea var. acephala DC.) at 20 ◦ C to define an adequate range of O 2 and CO2 partial pressures for product preservation. Different low O 2 and high CO2 atmospheres were tested. First, tolerance to low O2 partial pressures (1, 2, 3 or 21 kPa O2 with balance N2) was tested. Quality retention was improved as O2 partial pressure was reduced and there was no induction of anaerobic respiration. Then, tolerance to high CO2 partial pressures (0, 10, 15 or 20 kPa CO2 plus 21 kPa O2 and balance N2) was tested. The high CO2 partial pressures extended the shelf life of the shredded kale and no symptoms of CO2 injury were detected. Finally, combinations of low O2 and high CO2 (1 or 2 kPa O2 plus 15 or 20 kPa CO2, with balance N2, and an air control) were analysed. No differences were observed among the different gas combinations. An atmosphere of 1–2 kPa O2 plus 15–20 kPa CO2 and balance N2 extends the shelf life of shredded Galega kale to 4–5 days at 20 ◦ C, compared with 2–3 days in air storage. Predictive models of chlorophyll a and b degradation as a function of time and gas composition were developed.

Exposing pericarp tissue excised from immature tomato fruit to 4.5 mmol l 1 C2H4 revealed a negative C2H4 feedback mechanism in relation to its biosynthesis since ACC concentration and C2H4 production by the tissue were reduced. An opposite trend (positive C2H4 feedback mechanism) was observed in pericarp tissue excised from fruit at the pink stage. At the mature-green stage however, tissue showed a transition from negative to positive C2H4 feedback mechanism with the onset of tissue ripening. In strawberry tissues excised from green, white and half-coloured fruits however, C2H4 application caused a short-term increase in C2H4 production followed by a sharp reduction to the control level along with a marked reduction in ACC levels. In both tomato and strawberry fruit tissues, C2H4 application significantly induced ACC oxidase (ACO) activity at all ripening stages, as measured by in vivo ACC conversion to C2H4. This strongly suggests that ACC synthesis is the limiting step in C2H4 autocatalysis and the only limiting step in C2H4 autoinhibition. In tomato pericarp tissues, C2H4 autoinhibition and autocatalysis caused by C2H4 application in immature and pink fruits, respectively, were eliminated when tissues were transferred to air and re-occurred when tissues were returned back to C2H4. These responses did not occur in all strawberry tissues due to the sharp reduction in C2H4 production with the time course of C2H4 application. Inhibiting C2H4 action with STS pretreatment inhibited both negative and positive C2H4 feedback mechanisms in both tomato and strawberry tissues indicating that C2H4 feedback mechanism is one sort of C2H4 action. In addition, only tomato fruit tissue showed significant increases in CO2 production with C2H4 application. In contrast to the nonclimacteric behaviour of strawberry fruit which exhibits only a negative C2H4 feedback mechanism, these data strongly suggest that the transition of the C2H4 feedback mechanism from negative to positive, which occurs in tomato fruit only with ripening initiation and progress, may be the reason behind the climacteric behaviour of tomato fruit. © 2000 Elsevier Science B.V. All rights reserved.

Ethylene production by locule gel tissue excised from immature tomato fruit was inhibited by exposure to 4.5 mmol l 1 C2H4, and 1-aminocyclopropane-1-carboxylic acid (ACC) content was reduced. In contrast, CO2 production, ethylene forming capacity (EFC), red colour development, tissue liquefaction and seed maturation as measured by subsequent germination rate were stimulated by C2H4, and, in immature gel, the onset of autocatalytic C2H4 production was hastened. The autoinhibition of C2H4 production in immature locule gel tissue required continuous exposure to C2H4, as transfer to air and then back to C2H4 resulted in C2H4 production first increasing to control levels, then decreasing again. Locule gel tissue from pink fruit however, responded to C2H4 treatment with increased C2H4 and CO2 production, but ACC levels were unchanged. Inhibition of C2H4 action by pretreatment with STS inhibited both autoinhibition and autostimulation of C2H4 production in immature and mature gel tissues, respectively. These results indicate that there is a transition from a negative to a positive feedback mechanism of C2H4 on C2H4 biosynthesis in locule gel during ripening. Control of this feedback mechanism, which involves ACC synthesis, may be separate from that of other manifestations of C2H4 action. © 2000 Elsevier Science B.V. All rights reserved.

Two types of fruit coatings were tested for their effect on external and internal mango fruit atmospheres and quality factors during simulated commercial storage at 10 or 15°C with 90‐99% RH followed by simulated marketing conditions of 20°C with 56% RH. One coating was polysaccharide-based while the other had carnauba wax as the main ingredient. These two coatings exhibited markedly different O2 permeability characteristics under laboratory conditions. This confirmed what has been reported in the literature, that polysaccharide coatings are less permeable to respiratory gases, such as O2, and more permeable to water vapor compared to carnauba wax. When applied to fruit under simulated commercial conditions, however, the difference between the coatings in permeance to respiratory gases were much reduced, most likely due to the high humidity during chilled storage. Both coatings created modified atmospheres, reduced decay, and improved appearance by imparting a subtle shine; but only the polysaccharide coating delayed ripening and increased concentrations of flavor volatiles. The carnauba wax coating significantly reduced water loss compared to uncoated and polysaccharide-coating treatments. © 1999 Elsevier Science B.V. All rights reserved.

A procedure to maintain desired levels of O2 and CO2 inside packages that are exposed to different surrounding temperatures was designed and tested. This procedure included the design of packages for a high temperature, ambient atmosphere conditions simulating retail display conditions and the use of a controlled atmosphere (CA) environment surrounding the packages at a lower temperature simulating storage or transport conditions. To test the concept, strawberries and snap beans were held at 7°C for 4 days and 19°C for 2 days to simulate mixed storage:transport and retail display at these respective temperatures. The strawberries were stored in jars fitted with a short tube to modify the interior atmosphere; snap beans were stored in commercially available, semipermeable plastic bags. Both package types were placed in a CA of 14.8% O2 plus 8.3% CO2 at 7°C followed by storage in air at 19°C. Under these conditions, it was possible to maintain atmospheres that were close to the desired atmospheres for the products at both temperatures. © 1999 Elsevier Science B.V. All rights reserved.

Fruit of many mango (Mangifera indica L.) cultivars are susceptible to an internal disorder often referred to as either jelly seed, soft nose, or stem-end cavity (SEC), depending on the symptoms that appear when fruit are cut open. It has not been determined if jelly seed, soft nose, and SEC are different disorders or different symptoms of the same disorder. Sections of fruit mesocarp from the cultivars Irwin, Tommy Atkins, and Van Dyke were examined by light microscopy to characterize the disorder and discern histological differences or similarities among fruit with each of the three types of symptoms. Jelly seed and SEC affected fruit during early fruit ontogeny, whereas soft nose symptoms were detected only in fully developed fruit. No major microscopic differences were detected among fruit with jelly seed, soft nose or SEC. In fruit with each type of symptom, disorganization of the cells and rupture of the cell walls were the first microscopic indicators of the disorder, followed by deterioration or dissolution of vascular connections between the stone and the mesocarp. Stem-end cavity resulted in necrosis of the mesocarp around the cavity. No cavity or tissue necrosis developed around the stone in fruit affected with jelly seed or soft nose. The presence of Ca oxalate crystals was observed only in fruit with SEC. Based on temporal and spatial differences in symptom development within the fruit, it appears that soft nose, jelly seed and SEC may be classified as separate disorders.

‘Chandler’, ‘Oso Grande’ and ‘Sweet Charlie’ strawberries were forced-air precooled after delays of 0 or 6 h at 30 °C to study the effect of delaying precooling on physical and chemical quality characteristics of strawberry fruit. Fruit pulp temperatures were equilibrated to 30 °C prior to the start of each experiment to minimise water loss differences between treatments. Evaluations were made after storage for one week at 1 °C plus one day at 20 °C. Delaying the start of precooling resulted in about 50% greater water loss than in control fruit, which was evident as increases in superficial shrivelling. Tissue firmness values were also 14–22% lower in fruit from the delayed treatment. Fruits were darker (lower L ∗ value), less bright (lower chroma) and apparently less red (lower a ∗ value) with the cooling delay, although hue angle was also lower, which may reflect the occurrence of browning. No significant differences in pH were observed in these experiments, but titratable acidity was slightly lower with the delay to cooling. Delaying precooling also caused increased losses of ascorbic acid, soluble solids, fructose, glucose and sucrose compared to controls. In spite of differences related to harvest time and the variability among cultivars, the general responses were quite similar and illustrate the importance of rapid precooling and subsequent storage at low temperature for maintenance of acceptable appearance, texture and nutritive value of strawberries.