The present study was performed to characterize the physiological responses of cantaloupe [Cucumismelo (L.) var. reticulates`Athena'] fruit harvested at preripe (1/4 slip), half-slip, and full-slip stages of development and treated with 1-methylcyclopropene (1-MCP) prior to storage at 13 or 15 °C. Cantaloupe fruit (1/4 to full-slip stage) were treated with 1-MCP (0.01 and 1 μL·L-1) for 18 hours at 20 °C and then stored at 15 °C (pre-ripe fruit) or 13 °C (half- and full-slip fruit). The firmness of pre-ripe `Athena' fruit was significantly retained in response to 1 μL·L-1 1-MCP, but did not differ greatly from control fruit in response to 0.01 μL·L-1 1-MCP. Control fruit reached an edible condition (≈70 N) after 6 days of storage at 15 °C and persisted until day 12 (50 N), whereas 1 μL·L-1 1-MCP-treated fruit reached an edible stage after 17 days and persisted through 21 days (over 60 N). Fruit treated with 1-MCP exhibited slightly (0.01 μL·L-1) or dramatically (1 μL·L-1) lower electrolyte leakage throughout storage. 1-MCP (1 μL·L-1) significantly suppressed ethylene production and respiratory rates of pre-ripe cantaloupe during storage at 15 °C. Firmness retention was also highly significant for cantaloupe harvested and treated with 1-MCP (1 μL·L-1) at the half-slip and full-slip stages of development. 1-MCP treatment had a significant effect at reducing decay incidence and the occurrence of depressed or sunken regions of the fruit surface.
Jiwon Jeong and Donald J. Huber
Pre-ripe `Booth 7' avocado (Persea americana Mill.) fruit, a cross of West Indian and Guatemalan strains, were treated with 0.9 μL·L-1 1-methylcyclopropene (1-MCP) for 12 hours at 20 °C. After storage for 18 days in air at 13 °C, at which time whole fruit firmness values averaged about 83 N, half of the 1-MCP-treated fruit were treated with 100 μL·L-1 ethylene for 12 hours and then transferred to 20 °C. 1-MCP delayed softening, and fruit treated with 1-MCP retained more green color than air-treated fruit when full ripe (firmness 10 to 15 N). 1-MCP affected the activities of pectinmethylesterase (EC 18.104.22.168), α-(EC 22.214.171.124) and β-galactosidases (EC 126.96.36.199), and endo-β-1,4-glucanase (EC 188.8.131.52). The appearance of polygalacturonase (EC 184.108.40.206) activity was completely suppressed in 1-MCP-treated fruit for up to 24 days, at which time the firmness of 1-MCP-treated fruit had declined nearly 80% compared with initial values. The effect of exogenous ethylene applied to partially ripened 1-MCP-treated fruit differed for different ripening parameters. Ethylene applied to mid-ripe avocado exerted no effect on the on-going rate or final extent of softening of 1-MCP-treated fruit, even though polygalacturonase and endo-1,4-β-glucanase activities increased in response to ethylene. β-galactosidase decreased in 1-MCP-treated fruit in response to ethylene treatment. 1-MCP delayed the increase in solubility and depolymerization of water- and CDTA (1,2-cyclohexylenedinitrilotetraacetic acid)-soluble polyuronides, likely due to reduced polygalacturonase activity. At the full-ripe stage, the levels of arabinose, galactose, glucose, mannose, rhamnose, and xylose associated with the CDTA-soluble polyuronide fraction were similar among all treatments. In contrast, the galactose levels of water-soluble polyuronides declined 40% and 17% in control and 1-MCP treated fruit, respectively. Hemicellulose neutral sugar composition was unaffected by 1-MCP or ethylene treatment. The data indicate that the capacity of avocado fruit to recover from 1-MCP-mediated suppression of ripening can be only partially amended through short-term ethylene application and differs significantly for different ripening parameters.
Jiwon Jeong, James Lee and Donald J. Huber
This study was performed to characterize the physiological responses of tomato (Lycopersicon esculentum L.) fruit harvested at either 10% to 30% or 30% to 60% color change and treated with two forms of 1-methylcyclopropene (1-MCP). Tomato fruit were treated either by submersion for 1 min in 1-MCP aqueous solution at the ambient temperature or by exposure for 12 h at 20 °C in air with 1-MCP gas, then stored at 20 °C. The concentrations (1.0, 5.0, or 10.0 μL·L-1) in 1-MCP aqueous solution were achieved through addition of 0.5, 2.5, or 5.0 g of AFxRD-300 powder (2.0% formulation, Agro-Fresh, Inc.) to 10 L of the de-ionized water, following manufacturer's instructions. 1-MCP (0.5 μL·L-1) gas in a 174-L container was achieved through addition of 0.22 g of SmartFresh® powder (0.14% formulation, Agro-Fresh, Inc.) to 100 mL of tap water. Both forms of 1-MCP significantly delayed ripening of fruit at the two initial ripeness stages, as noted by a significant delay in fruit softening and peel color change. The firmness of 30% to 60% color change tomatoes was significantly retained in response to gaseous or aqueous 1-MCP. Control fruit softened rapidly and reached the minimum marketable firmness value (about 5 N) within 8 days of storage at 20 °C, whereas fruit treated with gaseous 1-MCP (0.5 μL·L-1) or aqueous 1-MCP (1.0 or 5.0 μL·L-1) reached the same stage after 16, 20, or 24 days, respectively. Firmness retention was also highly significant for 10% to 30% color change tomatoes treated with both forms of 1-MCP. The highest concentration of aqueous 1-MCP (10.0 μL·L-1) did not result in a further delay in ripening compared with treatment at 5.0 or 1.0 μL·L-1 1-MCP.
Jiwon Jeong, James Lee and Donald J. Huber
Three experiments were performed to characterize the physiological responses of an Eastern United States shipper muskmelon (Cucumis melo L. var. reticulatus ‘Athena’) harvested preripe (¼ slip) and during ripening (half-slip, full-slip) to 1 μL·L−1 1-methylcyclopropene (1-MCP), a potent ethylene antagonist effective at significantly extending the time required for climacteric fruit to complete ripening. In the first experiment, preripe fruit were treated with 1-MCP (18 hour, 20 °C) before storage at 15 °C. Softening of preripe ‘Athena’ was significantly suppressed in response to 1-MCP, with firmness of control and 1-MCP–treated fruit declining ≈50% and ≈36% through 12 and 18 days of storage at 15 °C, respectively. By 21 days of storage, firmness of 1-MCP–treated remained near 70 N, minimally within the upper range of whole-fruit firmness values considered acceptable for consumption (50–75 N). Fruit treated with 1-MCP exhibited significantly lower ethylene production, respiratory rates, and electrolyte leakage throughout storage. In a second experiment, muskmelon were treated with 1-MCP (18 hours, 20 °C) at progressively advanced stages of ripening (half- and full-slip stages). Softening was significantly suppressed in half-slip fruit, declining ≈64% and ≈23% in control and 1-MCP–treated fruit, respectively, during 16 days of storage at 15 °C. Advanced-ripening, full-slip fruit were similarly affected, softening ≈60% and ≈25% in control and 1-MCP–treated fruit, respectively, during 10 days at 15 °C. In a third experiment designed to simulate possible commercial handling protocols, full-slip muskmelon were treated with 1-MCP (24 hours, 10 °C) and held at 10 °C for 5 days before transfer to 20 °C. Mesocarp firmness of 1-MCP and control fruit within 2 days of transfer to 20 °C had decreased ≈40% and ≈54%, respectively, compared with values at the start of the experiment. After an additional 2 days at 20 °C, the mesocarp tissue of the respective treatments had softened 42% and 70%. Fruit treated with the ethylene antagonist showed significantly delayed incidence of surface decay and sunken regions compared with control fruit.
Jiwon Jeong*, Jeffrey Brecht, Donald Huber and Steve Sargent
A study was conducted to determine the influence of the ethylene action inhibitor, 1-methylcyclopropene (1-MCP) on the shelf life and deterioration of fresh-cut cantaloupe (Cucumis melo var. reticulatus) during storage at 5 °C. Intact cantaloupe fruit, cv. Durango (3/4 to full-slip stage) were treated with 1-MCP (1 μL·L-1) for 24 h at 20 °C. Following cooling to 5 °C, the fruit were processed into ≈2.5-cm cubes and subsequently dipped in 1.34 mm sodium hypochlorite solution for 20 s. Fresh-cut cubes were stored in 1.7-L vented plastic containers for 12 d at 5 °C (85% RH). Intact fruit treated and stored under identical conditions were also examined. While 1-MCP-treated cantaloupe cubes were about 35% firmer than control cubes after the 24-h at 20 °C 1-MCP treatment, little softening occurred in either treatment during the subsequent 12-d at 5 °C storage period. In contrast, control and 1-MCP-treated intact fruit softened nearly 40% and 15%, respectively. 1-MCP did not significantly influence flesh color and soluble solid contents of either intact cantaloupe or fresh-cut cubes during storage at 5 °C. Increased decay incidence was observed in 1-MCP-treated fresh-cut cantaloupe cubes.
Muharrem Ergun, Jiwon Jeong, Donald J. Huber and Daniel J. Cantliffe
`Galia' (Cucumis melo var. reticulatus L. Naud. `Galia') melons exhibit relatively short postharvest longevity, limited in large part by the rapid softening of this high quality melon. The present study was performed to characterize the physiological responses of `Galia' fruit harvested at green (preripe) and yellow (advanced ripening) stages and treated with 1-methylcyclopropene (1-MCP) before storage at 20 °C. Treatment with 1.5 μL·L-1 1-MCP before storage delayed the climacteric peaks of respiration and ethylene production of green fruit by 11 and 6 d, respectively, and also significantly suppressed respiration and ethylene production maxima. Softening of both green and yellow fruit was significantly delayed by 1-MCP. During the first 5 d at 20 °C, the firmness of green control fruit declined 66% while 1-MCP-treated fruit declined 46%. By day 11, firmness of control and 1-MCP-treated green fruit had declined about 90% and 75%, respectively. The firmness of control yellow fruit stored at 20 °C declined 70% within 5 d while 1-MCP-treated fruit declined 30%. The 1-MCP-induced firmness retention was accompanied by significant suppression of electrolyte leakage of mesocarp tissue, providing evidence that membrane dysfunction might contribute to softening of `Galia' melons. The mesocarp of fruit harvested green and treated with 1-MCP eventually ripened to acceptable quality; however, under the treatment conditions (1.5 μL·L-1 1-MCP, 24 h) used in this study, irreversible suppression of surface color development was noted. The disparity in ripening recovery between mesocarp versus epidermal tissue was considerably less evident for fruit harvested and treated with 1-MCP at an advanced stage of development. The commercial use of 1-MCP with `Galia'-type melons should prove of immense benefit in long-term storage and/or export situations, and allow for retention of quality and handling tolerance for fruit harvested at more advanced stages of ripening.
Jiwon Jeong, Donald J. Huber and Steven A. Sargent
Ethylene is integrally involved in the ripening of climacteric fruit. The ability to prevent ethylene action, or manipulate fruit sensitivity to ethylene, would provide a powerful means of extending postharvest storage life of these fruit, particularly for those that ripen rapidly and/or that are not tolerant of low-temperature storage. In this study, 1-methylcyclopropene (1-MCP), an inhibitor of ethylene action, was used to investigate ripening, respiration, and ethylene production in avocado fruit. `Monroe' avocados were treated with 1-MCP (Ethylbloc®) for 24 h at 20 °C. The fruit were subsequently stored at 13 or 20 °C. Some fruit were exposed to 100 ppm ethylene at 13 and 20 °C before or after MCP treatment. As evaluated by flesh firmness, respiration rate, and ethylene evolution, 1-MCP completely inhibited the ripening of avocado fruit stored at 13 and 20 °C and 85% relative humidity. Ethylene evolution and respiration rates were dramatically depressed, greater than 95% and 52%, respectively, by 1-MCP. Whereas firmness of control fruit decreased from over 100 N to 10 N in as few as 7 days, fruit treated with 1-MCP remained firm (>45 N) for periods of up to 3 weeks at 13 °C. Treatment of avocado fruit with 100 ppm ethylene at 20 °C for 12 h did not overcome the influence of MCP treatment. Similarly, treatment with ethylene before MCP exposure did not circumvent the effects of the cyclic olefin on ripening. Current studies are addressing the effects of MCP concentration and exposure time on avocado ripening.
Jiwon Jeong, Donald J. Huber and Steven A. Sargent
1-Methylcyclopropene (1-MCP), an inhibitor of ethylene action, has been shown to extend the storage life of avocado fruit. Waxing is also known to extend the storage life of avocado by reducing water loss and modifying the fruit internal atmosphere. In this study, 1-MCP and waxing were used to investigate their effects on ripening characteristics in avocado fruit. Preclimacteric `Tower II' and `Booth 7' avocados were treated with 1-MCP (Ethylbloc®) for 12 h at 20 °C. Half of the fruit were waxed (Sta-Fresh 819F®, FMC Co.) after 1-MCP treatment. The fruit were subsequently stored at 13 °C or 20 °C at 85% RH. As evaluated by fruit firmness, ethylene evolution, and respiration rate, 1-MCP and waxing delayed the ripening of `Tower II' avocados stored at 20 °C. Fruit treated with both 1-MCP and wax had better retention of green peel color and fruit firmness, and the delayed climacteric pattern of ethylene evolution and respiration rates. Waxing reduced weight loss and retarded softening, but did not delay climacteric ethylene evolution and respiration rates. Whereas firmness of control fruit decreased from >100 N to 20 N in as few as 7 days at 20 °C, fruit treated with both 1-MCP and wax reached 20 N over 11 days at 20 °C. The firmness of `Booth 7' avocados treated with both 1-MCP and wax decreased from >170 N to 20 N over a 5-week period at 13 °C. Current studies are addressing the nature of the dramatic decrease in firmness of MCP-treated fruit.
Muharrem Ergun, Donald J. Huber, Jiwon Jeong and Jerry A. Bartz
The purpose of the present study was to investigate the role of ethylene action, via use of the ethylene antagonist 1-methylcyclopropene (1-MCP), on the senescence and quality of fresh-cut ripe papaya (Carica papaya L. `Sunrise Solo') fruit. Ripe papaya fruit were treated with 2.5 μL·L-1 1-MCP and immediately processed into fresh-cut slices or left intact. At 2-day intervals over 10 days at 5 °C, continuously stored slices were monitored for ethylene production, firmness, electrolyte leakage, color, sensory changes, and pathogen incidence. Slices freshly prepared from intact fruit stored under identical conditions were measured similarly. Ethylene production did not differ significantly between the treatments, although production rates were slightly but consistently higher in slices from intact control compared with intact 1-MCP-treated fruit. Mesocarp firmness of continuously stored slices and slices from fruit stored intact was significantly retained by 1-MCP. Firmness of continuously stored slices from 1-MCP-treated fruit declined 50% compared with 75% for control slices. Firmness of fresh-cut slices prepared from intact control and 1-MCP-treated fruit at each sampling interval declined 26% and 15%, respectively. Electrolyte leakage remained low and changed little in slices freshly prepared from fruit stored intact. Leakage from continuously stored papaya slices increased after 4 days, and after 6 days controls increased significantly compared with stored slices derived from papaya fruit initially treated with the ethylene antagonist. The flesh color of continuously stored slices or slices prepared from fruit stored intact was influenced by 1-MCP only during the later periods of storage. Microbial counts in stored slices or slices prepared at each sampling were generally unaffected by 1-MCP. Informal sensory analysis indicated that the edible shelf life was 6 days in stored slices from 1-MCP-treated fruit compared with 2 to 3 days for stored slices from control fruit.
Jiwon Jeong, Jeffrey K. Brecht, Donald J. Huber and Steven A. Sargent
A study was conducted to determine the effect of 1-methylcyclopropene (1-MCP) on textural changes in fresh-cut tomato (Lycopersicon esculentum, Mill.) slices during storage at 5 °C. The relationship between fruit developmental stage and tissue watersoaking development was also determined. Fresh-cut tomato slices prepared from light-red fruit that had been exposed to 1-MCP (1 μL·L-1 for 24 h at 5 °C) retained significantly higher pericarp firmness during storage at 5 °C for 10 d than slices from nontreated fruit or slices stored at 10 or 15 °C and they also had a significantly higher ethylene production maximum. 1-MCP (1 or 10 μL·L-1 for 24 h at 5 °C) had no affect on the firmness of fresh-cut, red tomato slices at 5 °C or on slices prepared from 5 °C-stored, intact red tomatoes. Nor did 1-MCP treatment have a significant effect on electrolyte leakage of tomato slices or intact fruit stored at 5 °C. Slices from fruit of the same developmental stage but with higher initial firmness values had less watersoaking development and responded better to 1-MCP treatment during 8 d storage at 5 °C. 1-MCP (1 μL·L-1) was more effective in reducing watersoaking in light red stage tomato slices when applied at 5 °C for 24 h compared with 1-MCP applied at 10 or 15 °C. Watersoaking development was also more rapid in fresh-cut tomato slices as initial fruit ripeness advanced from breaker to red stage. Our results suggest that watersoaking development in fresh-cut tomato slices is an ethylene-mediated symptom of senescence and not a symptom of chilling injury as had previously been proposed.