Extension of fresh-cut “Blanquilla” pear (Pyrus communis L.) shelf-life by 1-MCP treatment after harvest

‘Blanquilla’ pears processed as fresh-cut products are highly sensitive to browning and softening. Common postharvest methods, such as the use of antibrowning compounds and/or modified atmosphere packaging, fail to preserve ‘Blanquilla’ pear slices long enough to be marketable. However, treatment with 1-MCP before cutting and peeling considerably improved their textural properties (9.2 N vs. 1.1 N with and without 1-MCP treatment, respectively) and color (a* values of 1 vs. 5 after 15 d at 4 °C, for slices pear treated with 1-MCP and without treatment, respectively). These positive changes were closely related to a decrease in respiratory activity determined on whole pears after 3 months of storage in air at 0 ± 1 °C and 95% R.H. (0.40 ± 0.05 mmol CO₂ kg⁻¹ h⁻¹ vs. 0.77 ± 0.04 mmol CO₂ kg⁻¹ h⁻¹ with and without 1-MCP treatment, respectively) and ethylene production (1.18 ± 0.36 nmol C₂H₄ kg⁻¹ h⁻¹ vs. 5.751 ± 1.12 nmol C₂H₄ kg⁻¹ h⁻¹ for samples treated with and without 1-MCP, respectively). The use of 1-MCP allows fresh-cut ‘Blanquilla’ pears to be sold up to about 5 d after processing. Treatment with 1-MCP could be a viable alternative to common technologies for extending the shelf-life of ‘Blanquilla’ pears as a fresh-cut product.     

Improving storability of persimmon cv. Rojo Brillante by combined use of preharvest and postharvest treatments

The combined use of preharvest treatments, gibberellic acid (GA₃) or calcium nitrate, with 1-methylcyclopropene (1-MCP) treatment applied postharvest, was evaluated to improve the storability of ‘Rojo Brillante’ persimmon fruit, at both 1 and 15 °C. Properties linked to commercial quality, such as flesh firmness, external colour, total soluble solids and level of astringency, were evaluated at harvest, periodically during storage, as well as after subsequent shelf-life periods. At both storage temperatures, control fruit and calcium nitrate-treated fruit showed commercial quality for 20 d; the sole application of GA₃ delayed loss of firmness for 30 d while the treatment with 1-MCP by itself allowed storage of the fruit for 40 d. The combined use of calcium nitrate plus 1-MCP did not improve maintenance of quality any more than when 1-MCP was applied alone. The combination of GA₃ and 1-MCP delayed the symptoms of chilling injury, extending the storability at 1 °C for up to nearly 3 months. During storage at 15 °C, the combination of both treatments resulted in high-firmness values for 30 d, but did not prolong the storage period any longer than the 40 d reached by the sole application of 1-MCP. Irrespective of treatment, a loss of efficacy of the deastringency treatment was observed after 30 d of storage at 15 °C.     

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.     

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.     

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.     

Epicuticular wax content and morphology as related to ethylene and storage performance of ‘Navelate’ orange fruit

The effect of ethylene (2 μL L⁻¹) on total and soft epicuticular wax content and wax morphology has been investigated in mature ‘Navelate’ (Citrus sinensis, L. Osbeck) oranges held under non-stressful environmental conditions (22 °C and constant high relative humidity (90–95% RH)). In addition, the objective of the study was to understand whether the ethylene-induced changes in epicuticular wax might participate in the beneficial effect of ethylene reducing non-chilling peel pitting, by modifying peel water, osmotic or turgor potential, or disease incidence caused by Penicillium digitatum (Pers.:Fr.) Sacc. Ethylene increased total and soft epicuticular wax content in ‘Navelate’ fruit and induced structural changes in surface wax that might be related to the formation of new waxes. Changes in epicuticular wax morphology, but not in its content, might be involved in the protective role of ethylene reducing non-chilling peel pitting, although the beneficial effect of the hormone is not related to water stress. Cell water and turgor potentials in freshly harvested fruit and fruit stored in air under non-stressful conditions suggest that water stress is not a limiting factor leading to the development of this physiological disorder. In addition, the results indicated that formation of new waxes in fruit treated with ethylene may partially cover stomata, cracks or areas lacking wax occurring in stored fruit and is likely to improve physical barriers to P. digitatum penetration.     

Apparent synergism between the positive effects of 1-MCP and modified atmosphere on storage life of banana fruit

Fruit of cv. Gros Michel banana were treated with 1-MCP (1000 nL L⁻¹ for 4 h at 25 °C) and then packed in non-perforated polyethylene (PE) bags for modified atmosphere storage (MAP). The bags were placed in corrugated cardboard boxes and stored at 14 °C. Fruit were removed from cool storage and ripened at room temperature using ethephon. The length of storage life was determined by the change in peel color to yellow, after this ethephon treatment. Fruit treated with 1-MCP + MAP had a storage life of 100 days. The storage life of control fruit (no 1-MCP and no MAP) was 20 days. Fruit held in PE bags without 1-MCP treatment had a 40 day storage life, and the same was found in fruit treated with 1-MCP but without PE bags. 1-MCP is an inhibitor of ethylene action, but also inhibited ethylene production, mainly through inhibition of ACC oxidase activity in the peel. MAP inhibited ethylene production mainly through inhibition of ACC oxidase, both in the peel and pulp. The combination of 1-MCP treatment and MAP storage resulted in much lower ethylene production due to inhibition of both ACC synthase and ACC oxidase activity.     

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.     

1-Methyl cyclopropene extends postharvest life of spinach leaves

Senescence of detached spinach leaves either untreated or treated with 0.1 or 1.0 μL L^?1 1-MCP has been investigated. 1-MCP treated leaves had higher chlorophyll content and photosystem II potential quantum yield (Fv/Fm) and lower solute leakage than untreated leaves after storage in darkness at 23 °C for 6 d, indicating a delay of senescence. Ethylene production was increased in spinach supplemented with 1-MCP after 3 d storage and then declined to the rates of untreated leaves. 1-MCP treated spinach had higher ascorbic acid and glutathione concentrations, and a low oxidised/reduced ratio for both antioxidants. Accumulations of ammonium and protein degradation were reduced by 1-MCP. The results presented here indicate that inhibition of ethylene sensitivity can be successfully used to extend the postharvest life of spinach leaves.     

Effect of curing at different temperatures on biochemical composition of onion (Allium cepa L.) skin from three freshly cured and cold stored UK-grown onion cultivars

Onions are cured in order to form a complete, dry, outer skin which reduces water loss and suppresses incidence of disease, and can promote a darker skin finish. Currently in the UK, standard curing practises for onions involves heating at 28 °C for six weeks (65–75% RH), however, reducing curing temperatures may help to reduce energy usage. There is little empirical data on the effects of curing temperature on flavonol concentration in the skin of brown onions and on flavonol and anthocyanin concentration in the skin of red onions. Therefore, the aim of this study was to elucidate the compounds responsible for the change in onion skin colour when cured at different temperatures.Brown cvs. Sherpa and Wellington, and red onions cv. Red Baron, were cured at 20, 24 or 28 °C for six weeks. Replicated skin samples were analysed immediately after curing and after seven months cold storage at 1 ± 0.5 °C. Measurement of objective colour showed that skin of cvs. Sherpa and Wellington was darker and had a lower hue angle (H°) immediately after being cured at 28 °C compared to 20 °C. In contrast, skin of cv. Red Baron had a higher H° but no change in lightness (L*) when cured at 28 °C compared to 20 °C. Fructose, sucrose and glucose concentrations were analysed as they are thought to play a role in regulating the synthesis of flavonols and anthocyanins, both coloured compounds found in onion skin; however no significant correlations were found between colour data and sugar concentrations. Flavonols were measured in the skin of all cvs. and anthocyanins in the skin of cv. Red Baron. Quercetin glucoside and anthocyanin concentrations in the skin of onions cv. Red Baron immediately after curing were higher in those cured at 20 °C. Total flavonols and total anthocyanins were negatively correlated with H° in the skin of onions cv. Red Baron, but there was no similar correlation between total flavonols and H° for onion cvs. Sherpa and Wellington. This suggests that anthocyanins and flavonols may play a major role in varying skin colour of red onions cv. Red Baron cured at different temperatures; however, the difference between curing temperatures may not have been sufficient to represent a correlation between darkening of cvs. Sherpa and Wellington and flavonol concentration. Further investigation is therefore required to fully elucidate the compounds responsible for colour changes observed in brown onions.     

Ripening and sensory analysis of Guatemalan-West Indian hybrid avocado following ethylene pretreatment and/or exposure to gaseous or aqueous 1-methylcyclopropene

Previous reports showed that both gaseous and aqueous 1-methylcyclopropene (1-MCP) delay ripening of avocado (Persea americana Mill.), but there are no reports of the influence of 1-MCP on its sensory attributes. The objective of this study was to evaluate the effects of ethylene pretreatment and/or exposure to gaseous or aqueous 1-MCP on fruit ripening and sensory attributes of ‘Booth 7’ avocado, a Guatemalan-West Indian hybrid. Separate experiments were conducted during two seasons (2008 and 2009) with fruit harvested at preclimacteric stage in October (early season) and in November (late season). Fruit from Season 1 were exposed to ethylene (4.07 μmol L⁻¹) for 12 h at 20 °C, and stored for more 12 h at 20 °C in an ethylene-free (ethylene, <0.1 μL L⁻¹) room prior to treatment with either aqueous (1.39 or 2.77 μmol L⁻¹ a.i.) or gaseous (3.15 or 6.31 nmol L⁻¹ a.i.) 1-MCP. Ripening was monitored and firmness, respiration, ethylene production and weight loss were measured. Texture profile analysis and sensory analysis were performed on ripe fruit only (firmness, 10–15 N). Fruit from Season 2 were not exposed to ethylene pretreatment but treated only with aqueous 1-MCP 24 h after harvest. Fruit were assessed exclusively for sensory analysis when ripe (firmness, 10–15 N). Treatment with either 1-MCP formulation effectively delayed ripening from 4 to 10 d for early-season fruit, and from 4 to 6 d for late-season fruit. Higher concentrations of 1-MCP of either formulation had the greatest effect on selected pulp textural parameters of early-season fruit; the gaseous formulation had greater effect on late-season fruit quality than the aqueous formulation. In general, sensory panelists ratings of overall liking were not affected by 1-MCP treatment. Both aqueous and gaseous 1-MCP formulations delayed ripening of the Guatemalan-West Indian ‘Booth 7’ avocado without significant loss in appearance or in sensory attributes and, therefore, could be considered for use as a postharvest treatment for this hybrid.     

Genotypic differences in post-storage photosynthesis and leaf chloroplasts in response to ethylene and 1-methylcyclopropene in Aglaonema

This study investigated the effects of ethylene in storage and 1-methylcyclopropene (1-MCP) pretreatment on post-storage leaf senescence as measured by changes in photosynthesis and chloroplast degradation of two Aglaonema cultivars. Potted plants of ‘Chalit's Fantasy’ and ‘White Tip’ with or without 1-MCP treatment (600 nL L⁻¹ 1-MCP for 6 h) were exposed to 3.0 μL L⁻¹ ethylene, while being stored for 5 d at 16 °C in the dark, and then placed under an indoor environment for further observation. Plants that did not receive 1-MCP and ethylene served as controls. Ethylene did not affect the stomatal conductance in either cultivar. Ethylene reduced the net CO₂ assimilation rate and F_v/F_m (potential photochemical efficiency of photosystem II) in ‘White Tip’, but not in ‘Chalit's Fantasy’. Chloroplast number in a palisade or spongy mesophyll cell did not differ among treatments in ‘Chalit's Fantasy’. However, ethylene-treated ‘White Tip’ had fewer chloroplasts in the mesophyll cells, had more and larger plastoglobules in the chloroplasts, and had looser granal stacking with enlarged thylakoid lumens. ‘Chalit's Fantasy’ plants that were treated with 1-MCP before exposure to ethylene had higher net CO₂ assimilation rates and stomatal conductance than the control or plants that were exposed to ethylene without 1-MCP pretreatment. 1-MCP pretreatment mitigated the injurious effect of ethylene on ‘White Tip’ by increasing net CO₂ assimilation rate and F_v/F_m, and maintaining the quantity and structural integrity of chloroplasts.     

Physicochemical measurements in ‘Mondial Gala’ apples stored at different atmospheres: Influence on consumer acceptability

Standard quality parameters, consumer acceptability, emission of volatile compounds and ethylene production of ‘Mondial Gala^®’ apples (Malus × domestica Borkh.) were determined in relation to storage atmosphere, storage period and shelf-life period. Fruit were harvested at the commercial date and stored in AIR (21 kPa O₂:0.03 kPa CO₂) or under three different controlled atmospheres (CAs): LO (2 kPa O₂:2 kPa CO₂), ULO1 (1 kPa O₂:1 kPa CO₂), or ULO2 (1 kPa O₂:2 kPa CO₂). Fruit samples were analysed after 12 and 26 weeks of storage plus 1 or 7 d at 20 °C.Apples stored in CA maintained better standard quality parameters than AIR-stored fruit. The volatile compounds that contributed most to the characteristic aroma of ‘Mondial Gala^®’ apples after storage were butyl, hexyl and 2-methylbutyl acetate, hexyl propanoate, ethyl butanoate, ethyl hexanoate, ethyl, butyl and hexyl 2-methylbutanoate. Data obtained from fruit analysis were subjected to principal component analysis (PCA). The apples most accepted by consumers showed the highest emission of ethyl 2-methylbutanoate, ethyl hexanoate, tert-butyl propanoate and ethyl acetate, in addition to the highest titratable acidity and firmness values.     

Treatment with chlorine dioxide extends the vase life of selected cut flowers

The accumulation of bacteria in vase water is often associated with premature senescence in many cut flower species. In the present study, we tested the efficacy of aqueous chlorine dioxide (ClO₂) to extend flower display life by preventing the build-up of bacteria in vase solutions. The addition of 2 or 10 μL L⁻¹ ClO₂ to clean deionized water extended the vase life of Alstroemeria peruviana ‘Senna’, Antirrhinum majus ‘Potomic Pink’, Dianthus caryophyllus ‘Pasha’, Gerbera jamesonii ‘Monarch’, Gypsophila paniculata ‘Crystal’ and ‘Perfecta’, Lilium asiaticum ‘Vermeer’, Matthiola incana ‘Ruby Red’ and Rosa hybrida ‘Charlotte’ flowers by 0.9–13.4 d (7–77%) relative to control (i.e. 0 μL L⁻¹ ClO₂) stems. The beneficial effects of ClO₂ treatment were associated with a reduction in the accumulation of aerobic bacteria in vase water and on cut surfaces of flower stems. ClO₂ treatment was also effective in maintaining or extending the vase life of A. majus ‘Potomic Pink’, Dendrathema × grandiflorum ‘Albatron’, G. paniculata ‘Perfecta’ and M. incana ‘Ruby Red’ flowers even when stems were placed into water containing 10¹¹ CFU L⁻¹ bacteria. The efficacy of 10 μL L⁻¹ ClO₂ in vase water containing 0.2 g L⁻¹ citric acid and 10 g L⁻¹ sucrose to extend the display life of G. jamesonii ‘Lorca’ and ‘Vilassar’ flowers was equal to or greater than other tested biocides (i.e. aluminum sulfate, dichloroisocyanuric acid, 8-hydroxyquinoline sulfate, Physan 20™, sodium hypochlorite). Taken collectively, the results of the present study highlight the potential of aqueous ClO₂ for use as an alternative antibacterial agent in flower vase solutions.     

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.     

Influence of time from harvest to 1-MCP treatment on apple fruit quality and expression of genes for ethylene biosynthesis enzymes and ethylene receptors

A strong potent inhibitor of ethylene action, 1-methylcyclopropene (1-MCP) maintains apple fruit quality during storage. To understand the influence of time after harvest until 1-MCP treatment, we studied expression patterns of genes for ethylene biosynthesis enzymes and ethylene receptors in two apple cultivars, ‘Orin’ and ‘Fuji’, which differ in ethylene production. Ethylene production and expression of MdACS1, MdERS1, and MdERS2 were suppressed in all 1-MCP-treated ‘Fuji’ fruit, but in ‘Orin’, the later 1-MCP was applied after harvest, the less was the suppression of ethylene production and expression of these genes. In fruit in which 1-MCP had low efficacy (e.g., ‘Orin’ treated at 7 DAH), ethylene production and the level of MdERS1 were briefly reduced by 1-MCP treatment at 2 days after treatment, then began to increase. Since ethylene receptors negatively regulate the ethylene signalling pathway, the increased levels of ethylene production and ethylene receptors after 1-MCP treatment might reduce 1-MCP efficacy.