Combined treatment of aminoethoxyvinylglycine (AVG) and 1-methylcyclopropene (1-MCP) reduces melting-flesh peach fruit softening

The effects of postharvest application of aminoethoxyvinylglycine (AVG) and 1-methylcyclopropene (1-MCP) on ethylene production and fruit quality, and thus on transportation and shelf-life, were evaluated in melting-flesh peaches. AVG (150 mg L⁻¹) significantly reduced ethylene production, and the effect was enhanced in combination with 1-MCP (1 μL L⁻¹). However, fruit treated with AVG alone softened to untreated control levels 2 d after harvest (DAH). Treatment with 1-MCP significantly reduced the rate of softening until 2 DAH, but the fruit rapidly softened thereafter, and reached untreated control levels by 4 DAH. A combination of AVG and 1-MCP significantly reduced fruit tissue softening throughout ripening. The effect of each chemical on flesh firmness indicated that 1-MCP affected fruit response in the early stages of ripening up to 4 DAH, and AVG significantly reduced softening in the latter stages from 4 to 9 DAH. Peaches treated with AVG and 1-MCP retained their ground color during ripening, but the effect of each chemical on color is unclear. The present study indicates that combined treatment with AVG and 1-MCP significantly delays the ripening of melting-flesh peaches.     

Regulation of stony hard peach softening with ACC treatment

Controlling the rate of fruit softening in melting-flesh peaches is a primary goal of the fruit industry. Stony hard (SH) peach varieties lack the ability to synthesize 1-aminocyclopropane-1-carboxylic acid (ACC), the precursor of ethylene, which is required for fruit maturation. SH peaches thus have crisp flesh that remains firm during ripening. In this study, we developed a simple technique to stimulate fruit softening by a single spray application of ACC at a concentration of 10–20 mM, which was sufficient to allow ethylene synthesis and fruit softening. Higher concentrations of ACC increased ethylene production, and made the fruit softer. Ethylene synthesis was limited to the first 2–3 d after ACC treatment, after which fruit ceased softening and retained its remaining firmness. These results indicate that a single application of ACC solution can be used to regulate the process of fruit softening in SH peaches.     

Regulation of stony hard peach softening with ACC treatment

Controlling the rate of fruit softening in melting-flesh peaches is a primary goal of the fruit industry. Stony hard (SH) peach varieties lack the ability to synthesize 1-aminocyclopropane-1-carboxylic acid (ACC), the precursor of ethylene, which is required for fruit maturation. SH peaches thus have crisp flesh that remains firm during ripening. In this study, we developed a simple technique to stimulate fruit softening by a single spray application of ACC at a concentration of 10–20 mM, which was sufficient to allow ethylene synthesis and fruit softening. Higher concentrations of ACC increased ethylene production, and made the fruit softer. Ethylene synthesis was limited to the first 2–3 d after ACC treatment, after which fruit ceased softening and retained its remaining firmness. These results indicate that a single application of ACC solution can be used to regulate the process of fruit softening in SH peaches.     

1-MCP regulates ethylene biosynthesis and fruit softening during ripening of ‘Tegan Blue’ plum

To investigate the effects of postharvest application of 1-MCP on ethylene production and fruit softening, activities of ethylene biosynthesis and fruit softening enzymes were measured during postharvest ripening of plum (Prunus salicina Lindl. cv. Tegan Blue) fruit after being exposed to 1-MCP (0, 0.5, 1.0 or 2.0 μL L⁻¹) at 20 ± 1 °C for 24 h. Following the treatments, fruit were allowed to ripen at ambient temperature (20 ± 1 °C), and ethylene production in fruit, activities of ACS and ACO, ACC content and fruit softening enzymes (PE, EGase, exo-PG and endo-PG) in fruit skin and pulp were recorded at different intervals. Postharvest application of 1-MCP significantly delayed and suppressed the climacteric ethylene production with reduction in the activities of ethylene biosynthesis enzymes (ACS, ACO) and ACC content, and fruit softening enzymes (PE, EGase, exo-PG and endo-PG) in the skin as well as in pulp tissues. The reduction was more pronounced with increased concentrations of 1-MCP. 1-MCP treated fruit showed different rates of fruit softening and activities of ethylene biosynthesis enzymes in the skin and pulp tissues which warrant further investigation on regulation of gene expression related to these enzymes with the inhibitory effect of 1-MCP.     

Ethylene biosynthesis in apricot: Identification of a ripening-related 1-aminocyclopropane-1-carboxylic acid synthase (ACS) gene

Apricots are climacteric fruits with a high susceptibility to flesh softening and loss of flavor during postharvest storage, and most of the ripening processes are regulated by ethylene, which also has an effect on its own biosynthesis. To understand this process in apricot, inhibition of ethylene biosynthesis and perception was performed for studying key genes involved in the ethylene biosynthetic pathway. Apricots, cv. “Patterson”, were harvested with yellow-green ground color and immediately treated with either the ethylene perception inhibitor 1-methyl cyclopropene (1-MCP) at 10 μL L⁻¹ or the ethylene biosynthesis inhibitor aminoethoxyvinylglycine (AVG) at 1 g L⁻¹. After treatment, quality and physiological attributes such as firmness, color, total soluble solids, acidity, fruit weight, ethylene production and respiration rates were evaluated every 2 d until they ripened at 20 °C. Gene expression analysis was performed by quantitative polymerase chain reaction (qPCR). Both ethylene inhibitors were effective in reducing ethylene production, respiration rate and fruit softening. Three 1-aminocyclopropane-1-carboxylic-acid synthase (ACS) genes were characterized, but only the expression of ACS2 was highly reduced by ethylene inhibition, suggesting a key role in ethylene synthesis at ripening. Contrarily, ACS1 and ACS3 showed a higher expression under ethylene inhibition suggesting that the corresponding genes are individually regulated in a specific mode as observed in other climacteric fruits. Finally, changes in 1-aminocyclopropane-1-carboxylic-acid oxidase genes did not show a consistent pattern of ethylene modulation.     

Antioxidant systems of ripening avocado (Persea americana Mill.) fruit following treatment at the preclimacteric stage with aqueous 1-methylcyclopropene

Preclimacteric avocado (Persea americana Mill. cv. Booth 7) fruit were treated with aqueous 1-methylcyclopropene (1-MCP) at 0.93 and 9.3 mmol m⁻³ and then stored at 20 °C to investigate the effect of 1-MCP on antioxidant systems of mesocarp tissue during ripening. Exposure to 1-MCP concentrations significantly delayed softening and peak ethylene production. 1-MCP significantly delayed accumulation of total soluble phenolics, flavonoids, and total antioxidant capacity although levels eventually reached control fruit maxima. The influence of 1-MCP was more pronounced at the higher concentration. Activities of peroxidase [POD (EC 1.11.1.7)], superoxide dismutase [SOD (EC 1.15.1.1)], catalase [CAT (1.11.1.6)] and l-ascorbate peroxidase [APX (EC 1.11.1.11)] increased during early ripening of control fruit followed by slight (CAT) or significant (POD, APX) declines with further ripening. Increases in activities of all enzymes were delayed in proportion to 1-MCP concentration, and maximum activities attained during ripening were largely unaffected by 1-MCP. Postclimacteric declines in POD and APX were not observed at the higher 1-MCP concentration, possibly reflecting incomplete ripening. The results indicate that changes in antioxidant parameters of avocado fruit are not markedly influenced by 1-MCP but are delayed or altered in proportion to the general suppression of ripening as indicated by ethylene production and fruit softening trends. Together with previously published reports, the data also indicate that the effects of ethylene-action suppression on antioxidant parameters during ripening vary considerably among different fruits. Relationships between antioxidant systems, ethylene and ripening are discussed.     

The effects of ethylene, 1-MCP and AVG on sprouting in sweetpotato roots

Exogenous ethylene is commonly used as a commercial sprouting inhibitor of potato tubers. The role of ethylene in the control of sprouting of sweetpotato roots, however, is not known. The aim of this study was to investigate the role of ethylene in control of sprouting in sweetpotato roots by observing the effect of an ethylene synthesis inhibitor, aminoethoxyvinylglycine (AVG), and the ethylene antagonist, 1-methylcyclopropene (1-MCP), in the presence and absence of exogenous ethylene on root sprouting and associated sugar accumulation. Continuous exposure to 10 μl L⁻¹ ethylene, 24 h exposure to 625 nl L⁻¹ 1-MCP or dipping in 100 μl L⁻¹ AVG all inhibited sprout growth in sweetpotato roots of two varieties over 4 weeks of storage at 25 °C. The observations that both ethylene on its own and 1-MCP, which inhibits ethylene action, inhibit sprout growth indicate that while continuous exposure to exogenous ethylene leads to sprout growth inhibition, ethylene is also required for sprouting. In potato tubers ethylene is required to break dormancy, while continuous exposure inhibits sprout growth.Monosaccharide concentrations in ethylene, 1-MCP or AVG treated roots were lower than in untreated roots, and for ethylene treated roots this was associated with higher respiration rates. This is consistent with the activation of some additional process by ethylene which uses energy through sugar metabolism. 1-MCP and AVG both inhibited this increase in respiration rate and counteracted the decrease in monosaccharide concentrations. 1-MCP presumably counteracts the ethylene stimulation of this process, while the effect of AVG is attributed to its possible inhibitory effects on protein synthesis.     

A novel technique using 1-MCP microbubbles for delaying postharvest ripening of banana fruit

This study aimed to investigate the application of microbubble technology for delaying banana ripening. A preparation of 1-MCP designed for use as a form of aqueous micro bubble (MBs) solutions was formulated. Banana fruit were immersed in 500 nL L⁻¹ of aqueous 1-MCP microbubbles (1-MCP-MBs) or fumigated with 500 nL L⁻¹ 1-MCP, then stored at 25 °C for 8 days. 1-MCP-MBs were more effective in delaying postharvest ripening than conventional 1-MCP fumigation. 1-MCP-MBs reduced the respiration rate and ethylene production compared to the control and 1-MCP fumigated fruit. Moreover, 1-MCP-MBs delayed yellowing and maintained firmness of banana fruit during storage. These results indicate that 1-MCP-MBs can be used as an alternative method for delaying the postharvest ripening of banana fruit, and its application for other commodities needs to be further elucidated.     

Effect of 1-methylcyclopropene (1-MCP) on softening of fresh-cut kiwifruit,mango and persimmon slices

Ethylene production is enhanced by wounding during fresh-cut processing and the accumulation of this gas within the packages of fresh-cut fruit can be detrimental to their quality and shelf-life. The effect of 1-methylcyclopropene (1-MCP), an ethylene action blocker, applied before or after processing, on the quality of fresh-cut kiwifruit, mangoes and persimmons was evaluated during storage at 5 °C. Fresh-cut ‘Hayward’ kiwifruit slices softened at a slower rate and their ethylene production rate was decreased in response to 1-MCP application (1 μL L⁻¹ for 6 h at 10 °C) either before or after processing. A 2-min dip in 0.09 M (1%, w/v) CaCl₂ synergistically increased the effect of 1-MCP on firmness retention and 1-MCP did not affect the color (L* value) of fresh-cut kiwifruit slices. Softening and browning (decreasing L* value) were delayed when 1-MCP was applied directly on fresh-cut ‘Kent’ and ‘Keitt’ mango slices. Respiration rate of mango slices was not influenced by 1-MCP whereas the ethylene production was affected only towards the end of their shelf-life. Fresh-cut ‘Fuyu’ persimmons treated with 1-MCP after processing presented higher ethylene production rate, slower softening rate and slower darkening of color (decrease in L* value), whereas the respiration rate was not affected.     

1-MCP controls ripening induced by impact injury on apricots by affecting SOD and POX activities

The influence of 1-MCP on the response of apricots to mechanical injury (impact) and the potential involvement of oxidative stress was investigated. Apricots (Prunus armeniaca L. cv. Marietta) picked at an early ripening (commercial harvest) stage (11–11.5 °Brix) were dropped from 30 cm onto a flat, hard surface to simulate an impact injury; fruit were treated with 500 nl 1⁻¹ 1-MCP for 20 h at 20 °C before or after the impact injury. Injured fruit showed a substantial rise in ethylene production after 4 days, while in fruit treated with 1-MCP, this increase started after 6 days, with a production rate lower than that of injured fruit. Increase in the respiration rate was delayed for 1-MCP-treated injured fruit in comparison with untreated injured ones. Tissue softening was reduced by 1-MCP treatment, showing less tissue deformability. Scanning EM analysis of injured tissue revealed healthier cells in 1-MCP treated apricots. 1-MCP-treated the increase of superoxide dismutase activity (SOD) due to mechanical injury in the first 4 days and this behaviour was related to ethylene production. Peroxidase activity (POX) increased in injured tissue immediately but then remained stable; 1-MCP, particularly when applied before the impact, increased POX activity. These results indicate that using 1-MCP can control ripening acceleration of apricots induced by mechanical injury. SOD, POX, and ethylene relationships are discussed.     

Effect of 1-methylcyclopropene (1-MCP) treatment on sweet basil leaf senescence and ethylene production during shelf-life

The effect of 1-methylcyclopropene (1-MCP) on shelf-life and postharvest quality of sweet basil detached leaves was examined. Treatment with 0.2, 0.4 and 0.6 g m⁻³ 1-MCP for 8 h was conducted at 15 °C in the dark. After the treatment the leaves were packed in polyethylene bags then sealed and stored at 20 °C. All 1-MCP concentrations significantly increased the shelf-life of leaves compared to the untreated control, and leaf weight loss with 1-MCP treatment was minimal. 1-MCP treatment significantly retarded the degradation of chlorophyll and protein content of detached leaves during storage and decreased leaf ethylene production. 1-MCP treatment also significantly retarded the decrease of volatile oil percentage in detached leaves during storage compared to the control. Among 1-MCP concentrations, 0.4 g m⁻³ resulted in the maximum shelf-life as well as improved postharvest quality of the leaves. The results clearly indicate that a single treatment with 1-MCP may provide a feasible technique for extending the shelf-life and maintaining higher volatile oil percentage of sweet basil leaves.     

α-Farnesene and antioxidative enzyme systems in Asian pear (Pyrus serotina Rehd.) fruit

The effects of 1-methylcyclopropene (1-MCP) on ripening, superficial scald and concentrations of α-farnesene, conjugated trienols (CTols) and antioxidant enzyme activity of ‘KS₆’ Asian pear (Pyrus serotina Rehd.) were studied. 1-MCP treated (2 μL L^?1) or untreated control fruit were stored at 1 °C and 90–95% RH for up to 120 days. 1-MCP treated fruit were firmer than untreated fruit. Application of 1-MCP delayed skin color change. Scald appeared after shorter storage duration and was reduced, but not entirely controlled, with 1-MCP. Accumulation of α-farnesene and oxidation were slower in skin of 1-MCP treated fruit compared with controls. Catalase and peroxidase activities in untreated fruit either increased while activities decreased in 1-MCP treated fruit. Superoxide dismutase activity remained stable. The treatment of Asian pears with 1-MCP followed by cold storage maintained textural characteristics with less scald incidence.     

Efficacy of 1-MCP treatment in tomato fruit: 1. Duration and concentration of 1-MCP treatment to gain an effective delay of postharvest ripening

‘Raf’ tomato fruit were harvested at the mature-green stage and treated with 1-methylcyclopropene (1-MCP) at 0.5 (for 3, 6, 12 or 24 h) or 1 μl l⁻¹ for 3 or 6 h. Fruit were stored at 10 °C for 7 days and a further 4 days at 20 °C for a shelf life period. All 1-MCP treatments reduced both ethylene production and respiration rate and in turn retarded the changes in parameters related to fruit ripening, such as fruit softening, colour (a^*) change, and increase in ripening index (TSS/TA ratio). These effects were significantly higher when 1-MCP was applied at 0.5 μl l⁻¹ for 24 h. In order to obtain the maximum benefit from 1-MCP, this treatment would be the most suitable for commercial purposes.     

Physiology of fresh-cut ‘Galia’ (Cucumis melo var. reticulatus) from ripe fruit treated with 1-methylcyclopropene

‘Galia’ (Cucumis melo var. reticulatus L. Naud. cv. Galia) fruit were harvested at the three-quarter slip stage and treated with 1 μL L⁻¹ 1-methylcyclopropene (1-MCP) at 20 °C for 24 h. The fruit were processed and stored as fresh-cut cubes and intact fruit for 10 d at 5 °C. Ethylene production of fresh-cut cubes was approximately 4–5-fold higher than intact fruit at day 1. Afterward, the ethylene production of fresh-cut cubes declined significantly whereas that of intact fruit remained relatively constant at about 0.69–1.04 ng kg⁻¹ s⁻¹. 1-MCP delayed mesocarp softening in both fresh-cut and intact fruit and the symptoms of watersoaking in fresh-cut fruit. Continuously stored fresh-cut cubes and cubes derived from intact fruit not treated with the ethylene antagonist softened 27% and 25.6%, respectively, during 10 d storage at 5 °C while cubes derived from 1-MCP-treated fruit softened 9% and 17%, respectively. Fresh-cut tissue from 1-MCP-treated fruit exhibited slightly reduced populations of both total aerobic organisms and Enterobacterium, although the differences did not appear to be sufficient to explain the differences in keeping quality between 1-MCP-treated and control fruit. Based primarily on firmness retention and reduced watersoaking, 1-MCP treatment deferred loss of physical deterioration of fresh-cut ‘Galia’ cubes at 5 °C by 2–3 d compared with controls.     

Postharvest application of ethylene and 1-methylcyclopropene either before or after curing affects onion (Allium cepa L.) bulb quality during long term cold storage

The storability of onion bulbs is dependent on the incidence and rate of sprout growth. Exogenous ethylene applied continuously has been demonstrated to act as a sprout suppressant in onion. However, the ethylene binding inhibitor, 1-methylcyclopropene (1-MCP), can also suppress sprouting in onion. Given this seemingly contradictory result, the precise role that ethylene plays during onion storage and the effect of curing on its efficacy is not understood.‘Sherpa’ and ‘Wellington’ onion bulbs were treated before or after curing (28 °C for 6 weeks) with a single dose of 10 μL L⁻¹ ethylene or 1 μL L⁻¹ 1-MCP for 24 h at 20 °C, or no treatment (control). Replicated out-turns were sampled during 38 weeks storage at 0–1 °C. Sprout growth (31 weeks after harvest) was reduced in ‘Sherpa’ treated before curing with ethylene or before or after curing with 1-MCP. However, sprout growth of ‘Wellington’ was not affected by any treatment. Following treatment, the cured, thick-skinned ‘Wellington’ released a lower concentration of treatment gas compared with the newly harvested, thin-skinned ‘Sherpa’. Onion bulb respiration rate increased immediately after being treated with ethylene but to a lesser extent or not at all when treated with 1-MCP. Fructose concentrations of onions treated with ethylene or 1-MCP before curing were not significantly different, however, after curing concentrations were about 2-fold higher compared with the control. Mean glucose and sucrose concentrations for both cultivars were higher immediately after being treated before curing with ethylene or 1-MCP than control bulbs. It appears that inhibition of sprout growth can be achieved using just a short 24 h treatment with ethylene or 1-MCP. However, skin thickness or permeability, which is dependent on cultivar and curing, may affect ethylene or 1-MCP influx and therefore efficacy of sprout suppressant action.     

Response of climacteric-type guava (Psidium guajava L.) to postharvest treatment with 1-MCP

Guava (Psidium guajava L. cv. ‘Allahabad Safeda’) fruit harvested at the mature light-green stage were exposed to 300 and 600 nL L⁻¹ 1-methylcyclopropene (1-MCP) for 6, 12 and 24 h at 20 ± 1 °C, and held in either cold storage (10 °C) for 25 days or ambient conditions (25–29 °C) for 9 days. Most of the physiological and biochemical changes during storage and ripening were affected by 1-MCP in a dose dependent manner. Ethylene production and respiratory rates were significantly suppressed during storage as well as ripening under both the storage conditions depending upon 1-MCP concentration and exposure duration. 1-MCP treatment had a pronounced effect on fruit firmness changes during storage under both the conditions. The reduced changes in the soluble solids contents (SSC), titratable acidity (TA) and vitamin C content showed the effectiveness of 1-MCP in retarding fruit ripening. Vitamin C content in 1-MCP-treated fruit was significantly higher than in non-treated fruit, and those treated with 300 nL L⁻¹ 1-MCP for 6 h. The development of chilling injury symptoms was ameliorated to a greater extent in 1-MCP-treated fruit during cold storage and ripening. A significant reduction in the decay incidence of 1-MCP-treated fruit was observed under both the storage conditions. 1-MCP at 600 nL L⁻¹ for 12 h, in combination with cold storage (10 °C) seems a promising way to extend the storage life of guava cv. ‘Allahabad Safeda’ while 1-MCP at 300 nL L⁻¹ for 12 and 24 h or 600 nL L⁻¹ for 6 h, may be used to provide 4–5 days extended marketability of fruit under ambient conditions.     

Improved quality retention of packaged ‘Anjou’ pear slices using a 1-methylcyclopropene (1-MCP) co-release technology

After three months storage at 0.5 °C one quarter of a lot of ‘Anjou’ pears (Pyrus communis L.) were treated with 1 μL L^?1 of 1-methylcyclopropane (1-MCP) for 8 h at 20 °C and three quarters of the fruit were left untreated at 20 °C for the same time. Treated and untreated pears were then sliced, dipped in a commercial anti-browning solution and packaged in modified atmospheric bags. Packages, containing slices from 1-MCP treated fruit, were labelled as MCP1. Slices from two thirds of the untreated fruit had one of two secondary treatments applied: (1) multi-functional co-release sachets added to the package at the time of sealing (NT), or (2) an injection of 1-MCP to sealed packages to achieve a final concentration of 1 μL L^?1 (MCP2). The last third of the slices from the untreated lot of pears were sealed into packages with no further treatment (CK). The packages were kept at 5 °C. In-package ethylene concentrations were significantly lower for the NT treated slices. NT also significantly delayed and reduced net oxygen consumption in the package headspace compared with other treatments. The NT treatment also reduced incidence of browning induced by enzymes of microbial origin, termed secondary browning (SB), and better maintained the measured juiciness of slices. In contrast, the CK, MCP1 and MCP2 treatments showed a more rapid appearance and severity of SB. Slices in packages treated with NT retained higher tissue levels of butyl, hexyl and pentyl acetate, 6-methyl-5-hepten-2-one, butanol and hexanol during storage than any of the other three treatments.     

Effect of 1-methylcyclopropene (1-MCP) on reducing postharvest decay in tomatoes (Solanum lycopersicum L.)

1-Methylcyclopropene (1-MCP as SmartFresh™ technology), an ethylene antagonist, was evaluated for affecting postharvest decay caused by Alternaria alternata, Botrytis cinerea, and Fusarium spp. on ‘Quality 23’ and ‘Seminis 35’ tomatoes at green or pink stages. Fruit with natural or artificial infection were subjected to 1-MCP at 0.0 μL L⁻¹, 0.6 μL L⁻¹ for 12 h, and 1.0 μL L⁻¹ for 6 h. After 31-42 d storage, disease incidence and severity of individual diseases in 1-MCP treated fruit was significantly reduced compared with that of the untreated controls, except in one inoculated test for ‘Quality 23’ where severity of Alternaria rot in 1.0 μL L⁻¹ treated fruit were significantly higher than that of the untreated control. Fruit treated with 1-MCP at 1.0 L⁻¹ for 6 h also had significantly higher incidence of Alternaria rot in the inoculated ‘Quality 23’ and in the non-inoculated ‘Seminis 35’ compared with the fruit treated with 1-MCP at 0.6 μL L⁻¹ for 12 h. The results of this study indicate that 1-MCP can reduce postharvest decay within a certain storage period.     

Treatment with 1-MCP and the role of ethylene in aroma development of mountain papaya fruit

Mountain or highland papaya (Vasconcellea pubescens) is a climacteric fruit which develops a strong and characteristic aroma during ripening. The dynamics of aroma volatile production during ripening of whole papaya fruit were analysed by headspace-SPME. The main compounds produced by the fruit were esters (aliphatic and branched) and alcohols: the most abundant esters were ethyl acetate, ethyl butanoate, methyl butanoate and butyl acetate, comprising 88% of the volatiles in fully ripe fruit; butanol was the most abundant alcohol. Among the volatiles produced, ethyl butanoate, ethyl acetate, ethyl hexanoate and ethyl 2-methylbutanoate were found to be the most potent odour compounds. During ripening of mountain papaya fruit there was an increase in the total content of both esters and alcohols. In order to clarify the role of ethylene in aroma formation, mature fruit were treated with 0.3 μL L⁻¹ of 1-MCP (16 h at 20 °C) or with 2 g L⁻¹ Ethrel, and then allowed to ripen at 20 °C. The treatment of the fruit with 1-MCP inhibited the rise in ethylene production in the fruit, while Ethrel advanced the development of the climacteric phase. Most esters identified in mountain papaya were dependent on ethylene, showing an increase in production during ripening and in response to Ethrel treatment, and a strong reduction in response to 1-MCP treatment. The data presented provide evidence that most esters produced by mountain papaya are derived from fatty acids and amino acid metabolic pathways, both of them being affected by ethylene.