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The passion fruit hybrid cultivar 'Passion Dream' (PD) produces two cycles of fruiting per year, in the summer and winter. Self-hybridization of PD created various lines, including 'Ripens during Summer' (RS), which lacks the ability to abscise during winter, suggesting a seasonal nonclimacteric behavior. The two lines were characterized by several quality traits: PD produced high ethylene levels in both seasons; RS produced significantly less ethylene during summer and almost none during winter. The ratio of total soluble solids to titratable acidity (TSS/TA), and aroma volatiles production, as determined by solid-phase microextraction/gas chromatograph-mass spectrometer (SPME/GC-MS) techniques, and taste indices were highest in PD summer fruits and lowest in RS winter fruits. Peel color in PD was affected by environmental and storage temperatures, whereas RS fruits always showed a strong purple color. The present findings suggest that ethylene production levels in passion fruit greatly influence various ripening processes, including acid degradation, increased TSS/TA ratio, accumulation of aroma volatiles, and tastiness.

‘Granny Smith’ apples are highly susceptible to superficial scald, a symptom of chilling injury. For many crops, low temperature storage results in oxidative stress and chilling injury, caused by increased production of superoxide anions which in turn leads to the generation of other dangerous reactive oxygen species (ROS). Application, prior to cold storage, of low oxygen (LO2, −1 ) at 20 °C, was effective in reducing superficial scald in fruit following 24 weeks of cold storage. ROS levels were measured by confocal laser-scanning microscopy of apple peel treated with the fluorescent probe 2′,7′-dichlorodihydrofluorescein diacetate. In control fruit, ROS levels increased during cold storage and shelf-life and were very high after only 8 weeks, whereas in 1-MCP-, ethanol- and LO2-treated fruit, ROS levels remained low throughout storage. Gene-expression levels of ROS-scavenging enzymes were induced by the various pretreatments: catalase ( MdCAT ) was induced by LO2 treatment, whereas Mn superoxide dismutase ( MdMnSOD ) was induced by 1-MCP treatment. Polyphenol oxidase ( MdPPO ) gene expression levels were associated with scald symptom development and were highest in control fruit. Ethylene levels and expression of ethylene biosynthesis genes were correlated with α-farnesene levels and -farnesene synthase ( MdAFS ) gene expression in the variously treated fruit. Accumulation of the α-farnesene oxidation product, 6-methyl-5-hepten-2-one (MHO), was highest in control fruit after 8 weeks, in accordance with ROS accumulation. The LO2 pretreatment mechanism might involve production of anaerobic metabolites, causing a delay in ethylene and α-farnesene biosynthesis and oxidation; this is different from the mechansism of action of 1-MCP, even though both consequently reduce ROS accumulation and scald symptoms.

'Barhi' dates change their color from green to yellow during ripening and they are marketed as slightly astringent yellow fruits. 'Barhi' dates which contain above 25-27% total soluble solids (TSS) are regarded as matured and will have the desirable color, taste and texture. In order to improve the quality of 'Barhi' dates postharvest life, we study various indices, for determination of the best stage for fruit harvesting. During breaking stage from green to yellow there is an increase in ethylene emission which decreased when the fruit color was changed to complete yellow. There is high correlation between increased yellowing expressed as hue angle and reduction in ethylene emission. The decrease in ethylene production rate was also highly correlated with levels of TSS which was determined by near infrared (NIR) spectrometry. The highest ethylene production rate was found in yellow fruits with low TSS of 17%, while, high TSS level of 37% was correlated with low ethylene production rate. It is noteworthy that in fruits with high TSS levels (37%) although ethylene levels are low in the first week after harvest, later during storage at 20°C, ethylene levels increased probably because of fungal contamination. Our results show that the ethylene production rate at harvest time can be a good index for determination of 'Barhi' maturity.

We studied the contribution of the seed to avocado ripening, emphasizing its role in ethylene biosynthesis and response pathways. Transcription profiles of genes involved in ethylene biosynthesis (PaACO, PaACS1 and PaACS2) and action (PaETR, PaERS1 and PaCTR1) were studied in seeded and seedless avocado fruit during ripening at ambient and low temperatures and in response to exogenous ethylene and 1-methylcyclopropene (1-MCP). Seedless mature fruit had a shorter preclimacteric lag, faster softening, and higher respiration during ambient temperature ripening than seeded ones. Advanced ripening in seedless fruit was accompanied by higher levels of PaACO and PaACS1 expression at harvest, and these levels increased dramatically towards the climacteric peak. The expression of PaETR, PaERS1 and PaCTR1 increased in parallel with the onset of the ethylene burst in seedless fruit, whereas PaETR increase predominantly in seeded ones. Seedless fruit exhibited an earlier response to exogenous ethylene at the day of harvest, than seeded fruit. On day 1 after harvest, ethylene application elicited lower levels of ethylene in seeded than in seedless fruit, concomitantly with massive PaCTR1 augmentation. This suggests that the negative regulator PaCTR may moderate the effect of ethylene on seeded fruit. Cold storage induced biosynthesis and regulatory genes in both seedless and seeded fruit relative to their levels at ambient temperature. However, in the first and second weeks in cold storage, PaACO, PaACS1 and PaACS2 expression levels were much higher in seedless than in seeded fruit, which could explain the higher levels of ethylene and accelerated softening of the seedless fruit in cold storage. Seeded and seedless fruit responded similarly to ethylene or 1-MCP application prior to cold storage. Ethylene slightly induced ethylene production, but significantly increased CO2 output. 1-MCP equally and effectively delayed softening, reduced ethylene and CO2 production and expression of genes involved in ethylene biosynthesis and ethylene action in seeded and seedless fruit. Both at ambient temperature and in cold storage respiration was higher in seedless than seeded fruit. Our findings demonstrate that the seed is involved in regulation of ethylene responsiveness during ripening, and acts to delay climacteric in mature seeded fruit.

To elucidate the role of ethylene receptors in avocado ripening and storage, we have isolated avocado (Persea americana Mill. 'Arad') homologues of the ethylene receptor genes, referred to as PaETR and PaERS1. The basal levels of PaETR and PaERS1 mRNA in avocado mesocarp were very low at harvest and were hyperinduced by exogenous ethylene treatment. The expression of both genes also increased in parallel to the onset of climacteric ethylene peak, suggesting that increase in endogenous ethylene leads to increase in these genes' expression. Application of the ethylene inhibitor, 1-methylcyclopropene (1-MCP) at harvest delayed ethylene production and down-regulated expression of PaETR and PaERS1 genes. PaETR mRNA expression in tissues taken from various distances from the seed revealed that the expression was highest close to the base of the seed and was reduced gradually toward the blossom end. We suggest that ethylene receptors are involved in regulation of ethylene responsiveness during ripening and act to protect the tissue against ethylene injury.

Chilling injury (CI) symptoms in avocado (Persea americana Mill.) fruit, expressed as mesocarp discoloration, were found to be associated with embryo growth and ethylene production during cold storage. In cvs Ettinger and Arad most mesocarp discoloration was located close to the base of the seed and was induced by ethylene treatment in seeded avocado fruit. However, ethylene did not increase mesocarp discoloration in seedless fruit stored at 5 degrees C. Application of ethylene to whole fruit induced embryo development inside the seed. It also induced seedling elongation when seeds were imbibed separately. Persea americana ethylene receptor (PaETR) gene expression and polyphenol oxidase activity were highest close to the base of the seed and decreased gradually toward the blossom end. By contrast, expressions of PaETR transcript and polyphenol oxidase activity in seedless avocado fruit were similar throughout the pulp at the base of the fruit. Application of the ethylene inhibitor, 1-methylcyclopropene, decreased mesocarp browning, embryo development, seedling growth, and ion leakage, and down-regulated polyphenol oxidase activity. The results demonstrate that ethylene-mediated embryo growth in whole fruit is involved in the mesocarp response to ethylene perception and the development of CI disorders.

The efficacy of three methods of applying ethanol to prevent storage decay was tested on two cultivars of table grapes, ‘Superior’ and ‘Thompson Seedless’. Ethanol was applied by: (1) dipping grapes in 50% ethanol for 10 s followed by air drying before packaging; (2) placing a container with a wick and 4 or 8 ml ethanol/kg grapes inside the package; (3) applying 4 or 8 ml ethanol/kg grapes to paper and placing this paper above the grapes in the package. The grapes were stored for 6 or 8 weeks at 0 °C and assessed after an additional 3 days at 20 °C. All methods of application controlled decay as well as or better than a SO2-releasing pad. The ethanol impregnated paper caused high levels of berry browning, perhaps because of high levels of acetaldehyde inside the package. However, the taste of the berries was not impaired by any of the ethanol applications. The taste of ‘Thompson Seedless’ grapes stored for 8 weeks in modified atmosphere storage was affected by CO2 levels above 7%. Some methods of applying ethanol used here show promise as alternatives to SO2 to prevent decay of grapes during storage while maintaining fruit quality.

To prevent the rapid postharvest browning, litchi fruits can be fumigated with SO2, followed by a hydrochloric acid (HCl) dip to restore their red colour. Most fungal decay agents are sensitive to SO2 fumigation or acidification but the treated fruits are highly sensitive to infection by Penicillium commune and closely related species. The present study examined whether the addition of weak organic acids or pH homeostasis inhibitors, alone and in combination, could effectively control fungal growth under the physiological conditions that are relevant to litchi fruits. It was found that the fungus can proliferate in culture at pH > 2.5 and is capable of either alkalizing or acidifying the medium, depending on the initial pH and the extent of growth inhibition. Propionic, sorbic and decanoic acids progressively inhibited fungal growth at decreasing pH, presumably by inducing acid stress. Likewise, the inhibitors of pH homeostasis, omeprazole and erythrosin B, inhibited fungal growth, and their efficacy was significantly increased at lower pH and in combination with weak organic acids. Litchi fruits treated with sorbic acid in the presence of HCl were significantly less prone to decay by Penicillium. This study shows that it is possible to utilize low pH as a lever to prevent fungal development.

The preformed ( Z , Z )-1-acetoxy-2-hydroxy-4-oxo-heneicosa-12,15-diene (AFD) is the most active antifungal compound in avocado; it affects the quiescence of Colletotrichum gloeosporioides in unripe fruit. Ethylene treatment (40 μg l −1 ) of freshly harvested avocado fruits cv. Fuerte enhanced the expression patterns of genes encoding Δ 12 fatty acid desaturase ( avfad12 -3), fatty acid elongase (AVFAE, avfae1 ), their respective enzymatic activities, and the level of the AFD. Application of the ethylene-action inhibitor 1-methylcyclopropene (1-MCP) after harvest and prior to ethylene treatment resulted in inhibition of: avfad12-3 and avfae1 transcription, enzymatic activities and AFD accumulation. 1-MCP treatment of fruit harvested 280 and 360 days after fruit set delayed fruit softening and reduced their AFD content compared with that in untreated fruits. However, decay symptoms caused by C. gloeosporioides were differentially affected by 1-MCP treatment after harvest. In the early-harvested fruits, the initial level of the AFD was 1820 μg g −1 fresh wt and the inhibition of the AFD synthesis by 1-MCP did not reduce it below its threshold for inhibiting C. gloeosporioides . In contrast, in the late-harvested fruits, the initial level of the AFD was only 950 μg g −1 fresh wt, and the 1-MCP treatment reduced the level of the AFD below its inhibition threshold, enabling fungal development in unripe fruits. These results demonstrate temporal relationships among fruit firmness, the synthesis of the precursor of AFD, the AFD content, and quiescence of C. gloeosporioides , and suggest that in avocado fruits, the processes of fruit ripening and AFD induction are independent processes that are differentially affected by ethylene action during fruit ripening.

1-Methylcyclopropene (1-MCP), an ethylene action inhibitor, significantly delayed the ripening of the avocado cultivars ‘Ettinger’, ‘Hass’ and ‘Pinkerton’. Application of 1-MCP at low concentration (300 nl l−1), prior to the climacteric increase, was effective and delayed the onset of the climacteric peaks of CO2 and ethylene production. The delay was associated with reductions in fruit softening and in electrical conductivity (EC), the latter being an indicator of membrane permeability. The 1-MCP-treated ‘Ettinger’ and ‘Pinkerton’ avocado fruit maintained a greener peel color because of their lower levels of chlorophyllase activity and less chlorophyll breakdown. Treatment with 1-MCP at 300 nl l−1 prior to cold storage reduced chilling injury (CI) symptoms that are expressed as mesocarp discoloration and reduced polyphenol oxidase (PPO) and peroxidase (POD) activities in avocadoes stored at 5 °C for 3.5 weeks. PPO and POD activities were low in harvested fruit and increased significantly during cold storage and shelf life at 20 °C. 1-MCP was effective in reducing pulp browning in all the tested avocado cultivars. Mesocarp discoloration in avocado was found to be correlated with increases in EC values and PPO and POD activities.

During fruit ripening on the tree and after harvest some essential processes involve the production of the anaerobic metabolites, acetaldehyde (AA) and ethanol. These processes include the production of aroma volatiles and removal of fruit astringency. Acetaldehyde, a natural aroma component, is present in almost every fruit; it accumulates during ripening even under aerobic conditions, but to a much greater extent under partially or totally anaerobic conditions. Partially anaerobic conditions often occur during fruit ripening and under storage conditions, for example, through coating with waxes or other films, or in modified and controlled atmospheres. A requirement for anaerobic metabolites in normal ripening provided the initial indication that the application of such anaerobic metabolites might be beneficial for postharvest fruit quality. In some fruit it was found that application of ethanol or AA alone can affect fruit ripening on the tree, for example, in figs (to induce maturity), banana and persimmon (to remove astringency), and grape (to increase anthocyanins). In the postharvest period anaerobic metabolites may be applied to induce volatile production and to improve fruit aroma. In addition, it has been found that AA has fungicidal and insecticidal activity. Acetaldehyde and ethanol have been shown to be capable of retarding senescence and inhibiting ethylene production in plants, leading to less chilling injury symptoms in various fruit. However, anaerobic metabolites should be applied carefully, depending on the species and variety of the fruit. Subtropical fruit are among the most sensitive to anaerobiosis damage, but application of AA in high concentrations can be phytotoxic to all fruit.

Bananas have a short shelf life after ethylene treatment and there is a high commercial demand to increase the storage life of individual clusters at the retail stage. To extend the shelf life of ethylene-pretreated banana, two different forms of modified atmosphere packaging (MAP) were used. In the first, individual clusters of ethylene-pretreated bananas were stored in a range of microperforated polyethylene (PE) bags (25 μm) creating various MAPs. Storage in PE bags with low microperforation (PE8) that created an atmosphere with 11% CO2 and 12% O2 was the most effective treatment for delaying banana ripening. The banana clusters kept firmer with nice peel color after 1 week at 20 °C, but the humidity inside the bags caused some decay development on the crown cut. In the second type of MAP individual clusters of ethylene-pretreated bananas were stored in air-evacuated PE bags (80 μm) under light vacuum (550 mm Hg) for short periods of 24 to 48 hours followed by storage in the same PE bags after releasing the vacuum. Storing bananas in air-evacuated bags for 24 to 48 hours reduced O2 levels to 1% and increased the production of CO2 up to 30%, but perforating the bags dramatically reduced the CO2 level to around 9% and increased the O2 level to 12%. Storing ethylene-pretreated banana clusters under vacuum for a limited time (24 to 48 hours), did not cause any damage, although the levels of acetaldehyde (AA) and ethanol increased dramatically. The AA and ethanol levels of 150 and 300 μL·L–1, respectively, that accumulated in the PE bags did not cause any off-flavors; on the contrary, the taste panelists preferred these bananas. Adding ethylene absorbents (EAs) to the air-evacuated PE bags reduced the ethylene levels as well as the AA and ethanol levels in the bags, which indicate that EAs also absorbed the AA and ethanol volatiles. Storing ethylene-pretreated banana clusters under vacuum for 24 to 48 hours was the most effective treatment for delaying ripening and senescence in yellow bananas (stage 3 to 4).

Two organic coatings for post-harvest application on fruits have recently been developed in Israel and the USA. One coating is a colloidal solution based on beeswax (BeeCoat); the other is based on carnauba wax. Both organic waxes are in the product list of the Organic Materials Review Institute (OMRI, 2003) as regulated processing products. The main distinguishing feature between the two wax coatings is that beeswax coated fruits had a lusterless look, whereas the carnauba wax coated ones were shiny. Coating organic avocado and mango effectively reduced the water loss, shrinkage, chlorophyll breakdown, chilling injury symptoms and decay development in the fruits, thereby extending their shelf life. In mango cv. 'Tommy Atkins', coating with the beeswax-based organic wax, 'BeeCoat' decreased the rates of weight loss, fruit softening, color development and acid breakdown, thus ensuring a longer shelf life. Moreover, after 3 wks at 12°C following 10 days at 20°C, 'Tommy Atkins' coated with BeeCoat showed only a low level of the red spots which are symptomatic of chilling injury. In addition, the coated fruits did not develop anaerobic metabolites or off-flavors, and were preferred by the taste panelists. Coating bio-organic avocado cv. 'Ettinger' prior to cold storage for 3 weeks at 5°C followed by 8 d at 20°C, retained the green peel color and reduced the chilling injury symptoms expressed as internal and external distal end browning. Ripe uncoated 'Ettinger' fruits produced significant amounts of acetaldehyde (AA) and ethanol, whereas these volatiles were not detected in coated fruits. The higher level of anaerobic volatiles was correlated with greater mesocarp discoloration.

Cherry tomatoes harvested as bunches are sensitive to abscission during storage and this is a significant commercial problem for this produce. We examined effect of methyl jasmonate (MJ), ethylene and the inhibitor of its action, 1-methlcyclopropane (1-MCP) on abscission during storage and on the expression of six tomato endo-1,4-β-glucanases (EGase). It is reported that exogenous methyl jasmonate (1 mM) enhanced abscission during storage, as did ethylene (50 μL L−1). Application of 100 nL L−1 of 1-MCP for 24 h inhibited fruit abscission but only partial effect was obtained when it was applied 3 h after supplying methyl jasmonate or ethylene. The effects 1-MCP, methyl jasmonate and ethylene on expression of tomato endo-1,4-β-glucanases, Cel1, Cel2, Cel3, Cel 5, Cel7 and Cel8 were examined in abscission zone tissue at five time points during storage. The expression of Cel1 and Cel5 increased during storage, further establishing their role in abscission. Both ethylene and methyl jasmonate enhanced the expression of tomato endo-1,4-β-glucanases whereas, 1-MCP blocked the expression of the genes. These results demonstrate the benefit of 1-MCP in preventing fruit abscission and provide a wide view on the role of endo-1,4-β-glucanases in abscission of cherry tomatoes during storage.

Litchi fruits are fumigated after harvest with sulfur dioxide (SO2) to prevent their rapid browning. SO2 blocks enzymatic activity but bleaches the fruits and, if this process is followed by dipping the fruit in dilute hydrochloric acid, the appealing red color is regained. Hot water brushing (HWB) is among the alternative methods that were developed to replace the use of SO2. HWB reduced fungal population size on the surface of the fruit peel after treatment but did not eliminate fruit infection after storage. Whereas untreated fruits were infected with a variety of fungal species,Penicillium sp. was the only fungus that developed on the pericarp after storage in fruits that had been dipped in 1.5M HCl. Fruit treated by HWB followed by handling and storage under sterile conditions suffered greater decay than fruit stored under non-sterile conditions but with more ventilation. APenicillium sp. isolated from litchi grew well in liquid medium acidified to the pH range reported for SO2 and HCl-treated litchi fruits. Morphological analysis identified fungal isolates asP. aurantiogriseum. Internal transcribed spacer sequence analysis of five isolates suggested a sequence similarity toP. commune. Our data support the hypothesis that dipping litchi fruit in hydrochloric acid eliminates infection by common opportunistic fungi and selects forPenicillium species that tolerate low pH.

The emission of the metabolites, acetaldehyde (AA) and ethanol, from litchi fruit was monitored during maturation and storage. Juice extracted from the arils at various stages (green, breaker, pink and red pericarp) during the season, contained increasing amounts of AA and ethanol. These increases, in mature fruit, were accompanied by a pronounced decrease in the soluble solids content (SSC) and an increase in titratable acidity of the juice. In parallel to juice analysis at harvest, red pericarp fruit were packed in laminated films, creating modified atmosphere packaging (MAP). Late-harvested whole fruit in MAP produced more AA and ethanol than early-harvested ones. Intensified production of AA and ethanol was found in later-harvested litchi, during cold storage and shelf life in MAP, and late-harvested fruit also showed increased decay after cold storage. These results suggest that mature litchi fruit deteriorated when kept longer on the tree during the harvesting season. This may be ascribed to a fermentation process that began on the tree and caused deterioration during MAP storage.

Storage of mango (Mangifera indica L. cvs. Tommy Atkins and Keitt) fruits at 12°C caused slight chilling injury (CI) symptoms on the fruit peel, expressed as red spots around the lenticels (lenticel spotting). A modified atmosphere (5% CO2 and 10% O2) was created in 4-kg film-lined cartons by using microperforated polyethylene (PE) or Xtend ® film (XF). For ‘Keitt’ fruit, a similar atmosphere was also applied using controlled atmosphere chambers. After 3 weeks of storage at 12°C plus 1 week at 20°C, both modified and controlled atmosphere treatments were effective in reducing CI. The most effective reduction was found in fruits that were packed in the XF film. A second advantage of using XF film was the reduction in the level of sap inside the package due to the lower relative humidity in the XF film (90%) compared with that of PE packaging ( 99%). © 2000 Elsevier Science B.V. All rights reserved.

A combined hot water spray and fruit brushing (hot water brushing–HWB) treatment for 15–20 s was developed for reducing the incidence of postharvest disease caused by Alternaria alternata and improving mango fruit keeping quality. The efficacy of the hot water treatment was tested over a range of temperatures from 48 to 64°C, in combination with prochloraz treatment and fruit waxing. Hot water brushing of fruits significantly reduced decay (infected area) development by A. alternata. But after storage for 3 weeks at 12°C and another week at 20°C, the reduction of disease incidence by HWB and prochloraz treatment (900 μg ml−1) was more effective than by HWB alone. HWB treatment for 15 s improved colour development and was more effective than the common, commercial 5 min dip treatment at 55°C. The combination of fruit HWB and waxing yielded high quality fruits with less decay development.

An in vitro assay was used to determine the effect of AA and pH on the enzymatic and nonenzymatic production of ethylene (C2H4) from ACC. We were interested in the effect of AA on C2H4 production from ACC because aldehydes, primarily AA, can accumulate in tissue as the result of ripening, storage under modified atmospheres, packaging, and stress. Using crude extracts of ACC oxidase from tomato (Lycopersicon esculentum Mill. `Castlemart') and apple (Malus ×domestica Borkh. `Golden delicious'), C2H4 production from ACC was shown to increase in response to an increase in pH above 7.2 and inclusion of 0.2 to 2 mm AA. Nonenzymatic C2H4 production from ACC also increased linearly with increasing AA concentrations in all the buffers tested. Removal of ascorbate or O2 suppressed AA-induced nonenzymatic C2H4 production. Nonenzymatic AA-induced production of C2H4 from ACC appeared to be an ascorbate dependent oxidation, which was augmented by O2 and was sensitive to minor pH fluctuation. The nonenzymatic AA-stimulated conversion of AEC to 1-butene lacked stereospecificity. Formaldehyde and propionaldehyde also stimulated C2H4 production from ACC. These data indicate that ACC oxidase assays or C2H4 measurements assessing physiological status can be seriously affected by the presence of aldehydes, such as AA. Chemical names used: AA, acetaldehyde; ACC, 1-aminocyclopropane-1-carboxylic acid; AEC, 1-amino-2-ethylcyclopropanecarboxylic acid; ADH, alcohol dehydrogenase; EtOH, ethanol.

Exogenous application of acetaldehyde (AA) vapour to whole or half-peeled avocado fruits (Persea americana cv. `Fuerte'), prior to storage, inhibited fruit ripening. This inhibition was characterized by a delay in fruit softening and a reduction in ethylene production. Activities of the cell wall depolymerizing enzymes polygalacturonase (PG), β-galactosidase (β-GAL) and endoglucanase (Cx), and of 1-aminocyclopropane-1-carboxylic acid oxidase (ACC oxidase), were reduced immediately after treatment. AA-treated fruit had reduced ethylene production and ACC oxidase activity, both in vivo and in vitro. Levels of total free sulfhydryl (SH) group compounds increased in AA-treated fruit, but diminished in untreated fruit. AA treatment inhibited fruit pulp oxidation, while untreated control fruits oxidized and became brown. Application of AA to a PG reaction mixture reduced PG activity on sodium polypectate. Pre-incubation of the substrate with AA did not result in reduced activity. Attempts to detect AA-bound proteins in AA-treated fruits were unsuccessful.

There is increased demand for high quality fruit produced and marketed with reduced chemical inputs to minimize toxic effects on human health and the environment. Granny Smith (GS) apple quality is reduced by two major physiological disorders, superficial scald and bitter pit (BP). These disorders cause great loss to apple growers worldwide. Superficial scald is commonly controlled by chemical treatments, mainly the antioxidant diphenylamine (DPA) and/or the ethylene action inhibitor, 1-methylcyclopropene (1–MCP). Both chemicals are ineffective in controlling bitter pit incidence. We proposed to investigate the beneficial use of non-chemical, abiotic stress with low O2 (LO2) applied for 10d at 20°C on GS apple fruit. During the project we expanded the treatment to more apple cultivars, Golden Delicious (GD) and Starking Delicious (SD) and another pome fruit, the pear. Apple and pear have similar physiological disorders that develop during cold storage and we examined if the LO2 treatment would also be effective on pear. Application of 0.5% LO2 atmosphere for 10d at 20°C or 500ppb 1-MCP at 20°C prior to cold storage at 0°C, was effective in reducing superficial scald in GS apple. Moreover, LO2 pretreatment was also effective in reducing bitter pit (BP) development in California GS and Israeli GD and SD apples The BP symptoms in GS from California were much more prominent, so the effect of LO2 was more dramatic than the effect on the Israeli cvs. GD and SD, nevertheless the LO2 treatment showed the same trend in all cultivars in reducing BP. The LO2 and 1-MCP -treated fruit exhibited lower levels of ethylene, - farnesene and its oxidation product, 6-methyl-5-hepten-2-one (MHO), as determined by SPME/GC-MS analysis. In addition, LO2 pretreatment applied to California Bartlett or Israeli Spadona pears was effective in reducing superficial scald, senescent scald and internal breakdown after 4 m of cold storage at 0°C. For GS apple, low-temperature storage resulted in oxidative stress and chilling injury, caused by increased production of superoxide anions which in turn led to the generation of other dangerous reactive oxygen species (ROS). Using confocal laser-scanning microscopy and H2O2 measurements of apple peel, we observed ROS accumulation in control fruit, while negligible amounts were found in LO2 and 1-MCP treated fruit. Gene-expression levels of ROS-scavenging enzymes were induced by the various pretreatments: catalase was induced by LO2 treatment, whereas Mn superoxide dismutase was induced by 1-MCP treatment. We assume that LO2 and 1-MCP pretreated fruit remained healthier due to reduced production of ethylene and reactive oxygen substances, such as MHO, during cold storage. The LO2-treated apple exhibited greener peel and firmer fruit after 6 m of cold storage, and the fruit had high crispiness leading to high taste preference. In both pear cultivars, the LO2 treatment led to a reduction in internal breakdown and browning around the seed cavity. We tested the LO2 pre-storage treatment on a semi-commercial scale that would be applicable to a small organic grower by sealing the fruit within the plastic field bins. The treatment was most effective with a continuous flow of nitrogen through the bins; however, a single 6 hour flush of nitrogen was also fairly effective. In addition, we determined that it was very important to have the oxygen levels below 0.5% for approximately 10 days to achieve good scald control, not counting the time required to reduce the oxygen concentration. Our LO2 technology has been proven in this project to be effective in reducing several physiological disorders developed in pome fruit during cold storage. We hope that our non-chemical treatment which is friendly to the environment will be used in the near future for the organic apple and pear industry. The next step should be an analysis of the cost-benefits and commercial feasibility.

Mango fruit ripening is accompanied by increased ethylene production which coordinates the ripening process. Ethylene production in other fruit has been shown to be inhibited by acetaldehyde and ethanol. In unripe mango fruit the ethylene production is very low ( −1 h −1 ) and treatments with acetaldehyde and ethanol had concentration-dependent effects on ethylene production. The application of 1-aminocyclopropane-1-carboxylic acid (ACC) to acetaldehyde or ethanol treated fruit discs showed acetaldehyde to be capable of completely eliminating increased ACC oxidase activity, whereas ethanol did not. This suggests that acetaldehyde is capable of inhibiting the activity of ACC oxidase directly, or alternatively of preventing the increase in the enzyme, thereby providing a possible mechanism for retarding fruit ripening.

Summary The effectiveness of pre-storage treatments of nitrogen (low oxygen), heat and ethanol and acetaldehyde vapours were examined for their potential for improving mango storage. Mature green mango fruit (Mangifera indica L. cv. Keitt) were treated with low oxygen (< 3% oxygen, 97% nitrogen) for 72 h, acetaldehyde (0.12%) and ethanol (1%) vapours for 24 h or heat (38 ± 2°C) for 48 h prior to storage at 14°C. The nitrogen and ethanol treatments induced substantial levels of acetaldehyde and ethanol in the fruit. Initially the firmness of the nitrogen treated fruit remained higher than the control although later in storage this effect was lost. Differences in ripening were reflected in the total soluble solids and acidity levels, nitrogen maintaining a higher acidity and lower total soluble solids (less mature) whereas the heat treated fruit had lower acidity and higher total soluble solids (more mature). Ethanol and acetaldehyde treatments showed no effect. The use of a pre-storage treatment of nitrogen therefore had a beneficial effect on retarding ripening, although as storage progressed this effect was lost.

Prestorage treatment of avocado fruit (Persea americana Mill. cv. Fuerte) with a low-O2 atmosphere (3% O2 + 97% N2) for 24 hours at 17C, significantly reduced chilling injury (CI) symptoms after storage at 2C for 3 weeks. Fruit softening was also delayed by this treatment. The treated fruit had lower respiration and ethylene production rates during storage at 2C and subsequently at 17C. Electrolyte leakage was significantly lower in peel disks from treated fruit. Reducing power, expressed as total sulfhydryl groups, was higher in the peel and pulp of low-O2-treated fruit. The amount of peel chlorophyll was inversely correlated with the severity of CI symptoms.

Exposure to high CO 2 (95%) for 24, 36 and 48 h at 20°C enhanced ethylene and CO 2 production of ‘Golden Delicious’ apples during 2 subsequent weeks at 20°C. Greatest stimulation occurred following the 24 h treatment, and decreased as the exposure time increased. A progressive stimulation in ethanol and ethyl acetate occurred in fruit with increased duration of CO 2 treatments, whereas acetaldehyde levels remained unchanged. Treated apples softened and yellowed more than control fruit. There was no influence of CO 2 on total soluble solids content (SSC), but acidity was reduced in CO 2 -treated fruit, resulting in a higher SSC/acid ratio. CO 2 -treated fruit were rated by panelists as better flavoured than control fruit, with 24-h-treated fruit being the most acceptable after two weeks at 20°C.

Maintaining banana fruit in a low humidity environment accelerated fruit ripening. This was reflected in an earlier increase in respiration and ethylene production and more advanced peel colour and...

Summary Exposure of tomatoe fruits ( Lycopersicon esculentum Mill.) to 0.2–0.4 % acetaldehyde (AA) vapours for 24 h prior to storage caused inhibition of fruit ripening as expressed by less colour development. The endogenous levels of AA and ethanol found in the juice were positively correlated with the AA concentration applied. Application of 0.6% AA vapours for durations of 6 to 24 h also caused significant delay in colour development. Colour inhibition occurred with fruits harvested either at the breaker or turningpink stage. Application of a N 2 atmosphere or C0 2 at different concentrations (50–90%) for 48 h resulted in production of endogenous AA and ethanol. Inhibition of ripening was the highest after treatment with 98% N 2 or 90% CO 2 , which also led to the highest levels of AA and ethanol. Polygalacturonase (PG) activity was inhibited by AA as well as by CO 2 or N 2 pretreatments.

BACKGROUND: Californian Granny Smith apples are very susceptible to bitter pit (BP) and superficial scald symptoms that developduringcoldstorage.Themainpreventivemeansarediphenylaminedippingand/orgaseousapplicationoftheethylene inhibitor1-methylcylclopropene(1-MCP),whichiseffectiveagainstsuperficialscaldbutnotagainstBP.Thisstudyinvestigated the efficacy of a non-chemical alternative, low-O2 (LO2) stress, in preventing these two physiological disorders. RESULTS: Application of LO2 stress at 20 ◦ C for 10 days prior to cold storage of Granny Smith apples reduced superficial scald and BP incidence and severity during 8 months at 0 ◦ C. LO2 treatments induced volatile alcohols and reduced ethylene and 6-methyl-5-hepten-2-one (MHO-on) production, thereby reducing superficial scald development after 4 months at 0 ◦ C. In addition, LO2-treated fruits had higher pectin methyl esterase (MdPME) gene expression, similar to that of 1-MCP-treated fruits, associated with their higher firmness. Conversion of MHO-on to 6-methyl-5-hepten-2-ol (MHO-ol) in LO2-treated fruits may explain the lower scald development. CONCLUSION: The ratio between MHO-on and MHO-ol might serve as an index of superficial scald severity. Reduction of BP symptoms in LO2-treated fruits could be due to accumulation of volatile alcohols in the peel tissue. c � 2010 Society of Chemical Industry

Fruit deterioration is a consequence of a genetically-determined fruit ripening and senescence programs, in which developmental factors lead to a climacteric rise of ethylene production in ethylene-sensitive fruits such as tomato and banana. Breeding of tomato with extended fruit shelf life involves the incorporation of a mutation in RIN, a MADS-box transcription factor participating in developmental control signalling of ripening. The RIN mode of action is not fully understood, and it may be predicted to interact with other MADS-box genes to execute its effects. The overall goal of this study was to demonstrate conservation of ripening control functions between banana and tomato and thus, the potential to genetically extend shelf-life in banana based on tools developed in tomato. The specific objectives were: 1. To increase the collection of potential RIN-like genes from banana; 2. To verify their action as developmental regulators; 3. To elucidate MADS-box gene mode of action in ripening control; 4. To create transgenic banana plants that express low levels of endogenous Le-RIN- like, MaMADS- gene(s). We have conducted experiments in banana as well as in tomato. In tomato we have carried out the transformation of the tomato rin mutant with the MaMADS1 and MaMADS2 banana genes. We have also developed a number of domain swap constructs to functionally examine the ripening-specific aspects of the RIN gene. Our results show the RIN-C terminal region is essential for the gene to function in the ripening signalling pathway. We have further explored the tomato genome databases and recovered an additional MADS-box gene necessary for fruit ripening. This gene has been previously termed TAGL1 but has not been functionally characterized in transgenic plants. TAGL1 is induced during ripening and we have shown via RNAi repression that it is necessary for both fleshy fruit expansion and subsequent ripening. In banana we have cloned the full length of six MaMADS box genes from banana and determined their spatial and temporal expression patterns. We have created antibodies to MaMADS2 and initiated ChI assay. We have created four types of transgenic banana plants designed to reduce the levels of two of the MaMADS box genes. Our results show that the MaMADS-box genes expression in banana is dynamically changing after harvest and most of them are induced at the onset of the climacteric peak. Most likely, different MaMADS box genes are active in the pulp and peel and they are differently affected by ethylene. Only the MaMADS2 box gene expression is not affected by ethylene indicating that this gene might act upstream to the ethylene response pathway. The complementation analysis in tomato revealed that neither MaMADS1 nor MaMADS2 complement the rin mutation suggesting that they have functionally diverged sufficiently to not be able to interact in the context of the tomato ripening regulatory machinery. The developmental signalling pathways controlling ripening in banana and tomato are not identical and/or have diverged through evolution. Nevertheless, at least the genes MaMADS1 and MaMADS2 constitute part of the developmental control of ripening in banana, since transgenic banana plants with reduced levels of these genes are delayed in ripening. The detailed effect on peel and pulp, of these transgenic plants is underway. So far, these transgenic bananas can respond to exogenous ethylene, and they seem to ripen normally. The response to ethylene suggest that in banana the developmental pathway of ripening is different than that in tomato, because rin tomatoes do not ripen in response to exogenous ethylene, although they harbor the ethylene response capability This study has a major contribution both in scientific and agricultural aspects. Scientifically, it establishes the role of MaMADS box genes in a different crop-the banana. The developmental ripening pathway in banana is similar, but yet different from that of the model plant tomato and one of the major differences is related to ethylene effect on this pathway in banana. In addition, we have shown that different components of the MaMADS-box genes are employed in peel and pulp. The transgenic banana plants created can help to further study the ripening control in banana. An important and practical outcome of this project is that we have created several banana transgenic plants with fruit of extended shelf life. These bananas clearly demonstrate the potential of MaMADS gene control for extending shelf-life, enhancing fruit quality, increasing yield in export systems and for improving food security in areas where Musaspecies are staple food crops.

Three varieties of peaches and one variety of nectarines were treated for 24 h with acetaldehyde vapour, 86% CO 2 , or 97% N 2 immediately after harvest. The fruits were then held for 7 days at 20°C, or stored at 0°C, 90% RH before being kept at 20°C. Treated fruit softened more slowly than control fruit. Insoluble pectin content remained higher, and polygalacturonase activity increased more slowly in treated fruit. Immediately after treatment, ethanol content was much higher in treated fruit but decreased during the period at 20°C and was similar to control fruit after 7 days. Ethanol content of control fruit increased during ripening. Ethylene production was inhibited by both CO 2 and N 2 treatment, with the latter being more effective. Taste tests after 5 days at 20°C revealed a preference for the treated over the control fruit. N 2 -treated fruit was generally rated higher than CO 2 -treated fruit.

Application of acetaldehyde (AA) at 90 to 360 mM to intact grape berries (Vitis vinifera L. CV. Sultanina and Vitis vinifera L. CV. 103) caused an increase in CO 2 production rate and a reduction in ethylene evolution rate. The increase in CO 2 production rate was accompanied by a decrease in juice acidity without any change in the total soluble solids content. Addition of ACC to berry halves dramatically increased ethylene production, which was inhibited by AA. Ethanol, applied at the same concentrations as AA, neither caused a reduction in ethylene evolution nor inhibited the conversion of ACC to ethylene. Chemical name used: 1-aminocyclopropane-1-carboxylic acid (ACC). It is well established that under reduced 02 levels below 8% there is retardation of fruit senescence, generally by inhibition of fruit ripening processes, including respiration and ethylene production (Kader, 1986). The first metabolize formed under anaerobic conditions is AA, which is converted to ethanol by the enzyme alcohol dehydrogenase (Cossins, 1978; Kelly and Saltveit, 1988; Pesis and Avissar, 1989). However, application of AA vapors to various climacteric and nonclimacteric fruits like oranges (Citrus sinensis (L.) Osb.) (Fidler, 1968; Pesis and Avissar, 1989), figs (Ficus carica L.), blueberries (Vaccinium corymbosum L.), and strawberries (Fragaria × annanassa) (Janes et al., 1978) caused an increase in the CO 2 production. This increase was accompanied by a decrease in acidity in figs (Hirai et al., 1968) and oranges (Pesis and Avissar, 1989). Janes et al. (1979) found a stimulation of 0 2 uptake by potato (Solanurn tuberosum L.) tubers treated with AA and ethanol, but related this increase to a stimulation of the cyanide-resistant respiration. Grape is a nonclimacteric fruit (Biale, 1960) that is harvested preferably after it has reached minimum maturity standards since, after harvest, there is almost no change in quality indices (Nel- son et al., 1963). However; AA vapors influence the quality of grapes harvested early in the season by increasing their total soluble solids content (TSS) or decreasing their acidity (Pesis and Frenkel, 1989). In addition, AA vapors have a fungicidal effect on stored grapes, and AA-treated berries have been re- ported to remain firmer during storage, which may increase their resistance to fungal attack (Avissar et al., 1989). The purpose of this study was to investigate the effects of postharvest appli- cation of AA or ethanol on CO2 and ethylene production by grape berries.

The plant hormone ethylene regulates climacteric fruit ripening and plays a major role in the development of superficial scald in apple fruits during cold storage. The effect of cold storage at 0 degrees C on development of superficial scald and bitter pit (BP) in transgenic Greensleeves (GS) apples suppressed for ethylene biosynthesis was investigated. Four apple lines were used: untransformed GS; line 68G, suppressed for 1-aminocyclopropane-1-carboxylic acid (ACC) oxidase (ACO); and lines 103Yand 130Y, suppressed for ACC synthase (ACS). Fruits from the transformed lines 68G, 103Y, and 130Y produced very little ethylene during 3 months of cold storage at 0 degrees C and after subsequent transfer to 20 degrees C, whereas untransformed fruits produced significant ethylene during cold storage, which increased dramatically at 20 degrees C. Respiration, expressed as CO(2) production, was similar in all four apple lines. After 2 months at 0 degrees C, all apple lines showed some BP symptoms, but lines 68G and 103Y were more affected than untransformed GS or line 130Y. Both transformed and untransformed apples produced alpha-farnesene, but concentrations were lower in yellow fruit than in green fruit in all lines but 68G. Line 68G produced the most alpha-farnesene after 2 months at 0 degrees C, including both (E,E) alpha-farnesene and (Z,E) alpha-farnesene. Concentrations of (E,E) alpha-farnesene were 100 times greater than those of (Z,E) alpha-farnesene in all lines. After 4 months at 0 degrees C plus 1 week at 20 degrees C, untransformed GS apples exhibited the most superficial scald, whereas fruits from lines 68G and 103Y were less affected and line 130Y had no scald. Superficial scald severity was higher in green fruit than in yellow fruit in all affected lines. These lines also exhibited significant production of 6-methyl-5-hepten-2-one (MHO), a major oxidation product of (E,E) alpha-farnesene. Line 130Y neither exhibited superficial scald nor produced MHO. It is shown here that even transgenic apples suppressed for ethylene biosynthesis genes can produce alpha-farnesene, which in turn can oxidize to free radicals and MHO, leading to scald development.

Lurie, S., Pesis, E. and Ben-Arie, R., 1991. Darkening of sunscald on apples in storage is a non-enzymatic and non-oxidative process. Postharuest BioL Technol., 1: 119-125. Various treatments were evaluated in attempts to delay or prevent the darkening of color which occurs on the sunscalded peel of apples (Malus domestica Borkh. cv. Granny Smith) during storage. A preharvest ethephon spray to advance maturity at harvest, dips in various antioxidants before storage, storage in a controlled atmosphere (2% 0 2 +4% CO2), or at a range of temperatures, did not prevent the disorder; nor did storage in 70% 0 2 accelerate its severity. Concentration of aminoacids and reducing sugars in sun-damaged peel varied inversely with the severity of the scald. The phenolic content of scalded peel was higher than in healthy peel. Malonaldehyde was high in damaged peel at harvest but not after storage. These observations suggest that the color change of sunscalded peel during storage is due to non-oxidative, non-enzymatic processes.

Growth of Botrytis cinerea on sterilised kiwifruit (Actinidia deliciosa (A. Chev.) CF. Liang et A.R. Ferguson) cv. Hayward juice, showed that in vitro the fungus used glucose in preference to fructose as a carbon source. In addition, it metabolised citric, quinic, and malic acids as carbon sources. However, it was not able to utilise oxalic acid. Fumaric acid was the only acid to increase in the culture medium during growth of the fungus.

Hamlin, Pineapple and Valencia oranges were stored in controlled atmospheres (CA) of nitrogen, carbon dioxide or 0.1–0.7% acetaldehyde in air 8–24 hours and changes in seven volatiles during 0–8 days determined by gas chromatography. Increases in acetaldehyde, ehtyl acetate, ethyl butyrate and ethanol were noted in samples after nitrogen or carbon dioxide CA storage with maximum increase 1–2 days after treatment. Methanol, methyl butyrate and hexanal were unchanged. Flavor evaluations of control versus treated juice showed no consistent changes from any treatment. Acetaldehyde vapors had little effect on flavor or compositon, except for Hamlins, where acetaldehyde and ethyl butyrate levels increased.

Summary Grapes (Vitis Dinifera L. cv. 'Sultanina') harvested at the end of the 1985 ~ 1988 seasons, received postharvest application of acetaldehyde (AA) vapours for 24 - 40 h. Treatment with AA vapour at 20 "C or 0 "C reduced significantly the decay caused by several fungi : Botrytis cinerea, Rhizopus stolonifer, Aspergillus niger and Alternuria alternata. In grapes treated with 0.5% AA for 24 h, no R. stolonifer was found after 8 days of storage at 20 "C. Treatment with 0.25% AA vapour for 40 h of grapes cv. 'Perlette' inoculated with R. stolonifer reduced the decay by 897;.

Postharvest application of acetaldehyde (AA) vapour or anaerobic conditions of N, or C02 for 24 h to hand-picked feijoa (Feijoa sellowiana Berg) fruits caused the accumulation of volatiles, which increasedfruit aroma and flavour. The volatiles, AA, ethanol, ethyl acetate and ethyl butyrate, were produced at high concentrations in treated fruit held for 13 days in storage at 20°C whereas in the control fruits the levels remained very low. A sensory panel judged the treated fruits to be sweeter than the controls, although there was no significant difference in the total soluble solids or acidity between the treated and the non-treated feijoas. Treatment with 98% N2 for 24 h was most effective for volatile production. Moreover, fruits in the N2 treatment maintained the best appearance after storage for 13 days at 20°C. Key words: Feijoa sellowiana. Acca sellowiana, acetaldehyde, aroma volatiles, ethyl acetate, ethyl butyrate, taste. INTRODUCTION One of the most important processes accompanying fruit ripening is the increase in the production of volatile compounds which contribute to fruit aroma and flavour. Acetaldehyde (AA)

Production of volatiles was stimulated by the infection of Penicillium digitatum in 'Shamouti oranges. During 7 days of disease development, there was a progressive increase in the emanations of the anaerobic metabolites acetaldehyde, ethanol and ethyl acetate. There was also an increase in other volatiles including methanol, acetone, and ethylene, accompanied by a high production of CO2. The production of acetaldehyde, ethanol and CO2 in cultures of P. digitatum was, highest on the first day after inoculation, and decreased as the fungus developed. Ethyl acetate and ethylene increased when sporulation had already begun. Neither acetone nor methanol was found in P. digitatum in vitro. The increase of the volatiles in the infected oranges was due to the host-pathogen interaction and peel lesion. ZusammenfassungDie Produktion von fluchtigen Verbindungen verursacht durch Penicillium digitatum in Orangen und in Kultur Nach einer Infektion mit Penicillium digitatum an 'ShamoutL'-Orangen wurde die Produktion von fluchtigen Verbindungen angeregt. Wahrend der ersten 7 Tage der Krankheitsentwicklung wurde eine progressive Steigerung der Ausstromung der anaeroben Metaboliten Acetaldehyd, Athanol und Athylacetat beobacbtet. Ermitteit wurde auserdem eine Vemiehrung anderer fluchtiger Verbindungen wie Methanol, Aceton und Athylen, gekoppeh mit einer erhohten CO2-Produktion. Die Bildung von Acetaldehyd, Athanol und CO2 in P. digitatum-Kuhuren war am ersten Tag nach der Inokulation am hochsten, mit der weiteren Entwicklung des Pilzes wurde sie niedriger. Die Athylacetat- und AUthylenproduktion verstarkte sich, nachdem die Konidienbildung schon angesetzt hatte. Weder Aceton noch Methanol wurde in vitro in P. digitatum festgestellt. Die Zunahme von fluchtigen Verbindungen in infizienen Orangen war mit Wirt-Pathogen-Wechselwirkungen sowie Schalen-lasionen gekoppelt.

Summary Acetaldehyde (AA) vapour reduced the in vitro growth of the fruit-infecting fungi Botrytis cinerea and Rhizopus stolonifer, and decreased the respiration of R. stolonifer. Spore germination, germ tube elongation and sporulation were inhibited in both fungi. AA induced the leakage of electrolytes from B. cinerea and R. stolonifer membranes. The conductivity found in the fungal extracts was positively correlated with the AA concentration applied. The leakage of reducing sugars and amino acids suggest that cell membranes are irreversibly disrupted by AA as a first step in inhibition of the fungi in vitro. Key words: Acetaldehyde, Rhizopus, Botrytis, electrolyte leakage Introduction Acetaldehyde (AA) is a natural aroma component of fruits, and accumulates as they ripen (Fidler, 1968). AA appears to be involved in enhancing ripening processes (Hirai, Hirata & Horiuchi, 1968; Janes & Frenkel, 1978) and in improving the sensory quality, taste, flavour and aroma of fruits (Paz, Janes, Prevost & Frenkel, 1982; Pesis & Frenkel, 1989). Acetaldehyde is also known for its fungicidal and insecticidal properties. Several workers have demonstrated the ability of AA to inhibit the development of rots on various post-harvest crops. Thus, significant reduction

Application of acetaldehyde (AA) vapour (1500-6000 pl litre-') for 4 h, or at a constant concentration of 5000 pl litre-' for durations of I to 4 h, caused changes in the appearance and sensory quality of strawberries (Fragaria x ananassa Duch). Some of these treatments induced rapid production of the volatiles ethanol, ethyl acetate, and ethyl butyrate as found in the strawberry juice. Application of 5000 pl litre-' AA for only 1 h or of 1500 pl litre-' AA for 4 h induced volatiles in modest amounts, which increased fiuit aroma and improved taste as determined by a taste panel. A longer duration (3-4 h) of AA application of 3000-6000 pl litre-' caused Off-Jlavours in the berries. Acetaldehyde treatments for 4 h reduced decay development during storage for 4 days at 5°C following I day at 20°C.

Apple and pear fruits stored at low temperatures may suffer from chilling injury symptoms, caused by oxidative stress. Application of a low-oxygen (LO2) atmosphere (0.5%) for 10 d at 20°C or 500 ppb 1-methylcyclopropene (1-MCP) at 20°C for 24 h, prior to cold storage at 0°C, were equally effective in reducing superficial scald on ‘Granny Smith’ apples, after six months of cold storage at 0°C plus seven days at 20°C. Compared to untreated control fruit, the LO2 and 1-MCP-treated fruit produced less ethylene, a-farnesene and its oxidation product, 6-methyl-5-hepten-2-one (MHO), as determined by SPME/GC-MS technique. In addition, LO2 pretreatment applied to Californian ‘Bartlett’ or Israeli ‘Spadona’ pears, was effective in reducing superficial scald, senescent scald and internal breakdown, after 4–4.5 months of cold storage at –1°C or 0°C, respectively, plus five to seven days at 20°C. We assume that LO2 and 1-MCP pretreated fruit remained free of physiological disorders, due to the reduced production of ethylene and the oxidation product MHO during cold storage.