Delayed Color Development Research Articles

Growth Temperature Influences Postharvest Quality and Cold Tolerance of Green Harvested Dwarf Tomatoes During Storage

Effect of cultivation temperature during the phase of flowering and fruit development on tomato quality was investigated. Plants of two dwarf tomato cultivars “Ponchi Re” and “Tarzan,” were subjected to three different growth temperatures: 16, 22, or 28°C, starting at the flowering phase. Mature green fruit was harvested and subjected to shelf life at 20°C for 20 days or first stored at 4°C for 15 days, and then placed under shelf life conditions. Fruit quality was determined through red color development, soluble solid content (SSC), softening, weight loss, and cold tolerance. Higher cultivation temperature increased development and production of fruit. Deviation from the 22°C growth temperature led to increased soluble solid content in both cultivars, and smaller fruit diameter in “Tarzan.” Fruit grown at lower temperature had delayed color development during shelf life, and this was further delayed by prior cold storage. “Tarzan” showed more chilling injury (CI) symptoms than “Ponchi Re.” In our experiment, SSC can be manipulated by modulating cultivation temperature, but that it is not associated with CI tolerance. Delayed color formation at the lowest growth temperature observed in “Ponchi Re” tomatoes could be resulted in lower lycopene levels leads to lower ROS scavenging capacity. For “Tarzan” tomatoes, higher firmness at harvest, less softening, and lower weight loss during cold storage in fruit from the lowest cultivation temperature might positively correlated with increased membrane integrity, resulting in increased CI tolerance. This indicates that CI incidence depends on growth temperature and is cultivar dependent in dwarf tomato fruit.

Effect of Harvesting Stages and Calcium Chloride Application on Postharvest Quality of Tomato Fruits

Tomatoes are a good source of vitamins, minerals, antioxidants, and enzymes, which are beneficial to human health. They are one of the most commercially high-value vegetable crops that experience a huge postharvest loss after harvest. The present experiment is conducted to investigate the effect of different maturity stages (mature green, breaker, and half-ripe stage), pre- and post-harvest treatment with different concentrations (0.0%, 1.0%, 1.5%, and 2.0%, w/v) of calcium chloride (CaCl2) on the postharvest performance, antioxidant and enzymatic activity of lowland tomato fruits, stored at ambient temperature (28 ± 2 °C and 75 ± 5% RH). Tomato fruit of mature green stage treated with 2% CaCl2 significantly (p = 0.05) declined the ethylene production (15.53%), weight loss (16.43%), and delayed color development by slowly synthesizes the lycopene content as well as extended the shelf life. The maximum amount of total phenolic content (TPC) was demonstrated at the highest level of CaCl2 (2%) after 20 days of storage life at ambient conditions. The concentration of CaCl2 influenced the activity of different plant defense enzymes, and the higher doses of CaCl2 (2%) accelerated the activity of peroxidase (POD) (13%), polyphenol oxidase (POP) (7.3%), and phenylalanine ammonia-lyase (PAL) (8.5%) relative to that of the control samples. Therefore, the tomato producers and traders could extend the storage duration of tomato fruits by harvesting at the mature green stage and applying 2% CaCl2 in both pre-and postharvest at ambient storage conditions.

Effect of aquaculture water eutrophication on color development in Biolog EcoPlates

Biolog EcoPlates are useful tools to study the metabolic function of microbial community in water bodies; however, the influence of aquaculture water, which contains complex chemical compositions, on color development in Biolog EcoPlates, has not been clearly illustrated. Previously, we detected a delayed color development in original water samples, comparing to that in the tenfold diluted samples. The objective of this study was to evaluate the differences of average well color development (AWCD) and community-level physiological profiles (CLPP) between the original and tenfold diluted water samples collected from three intensive Litopenaeus vannamei culture ponds, and to explore potential causes of the delayed color development by measuring microbial community structure and physiochemical indexes. Compared with the tenfold diluted samples, the original water samples from all three ponds exhibited delayed color development and reduced microbial metabolic activity. The original water samples exhibited higher utilization of carbohydrates, while significantly higher utilization of amino acids was observed in the corresponding diluted samples. The CLPP of the original water samples was significantly correlated with the microbial community structure at 48 h of incubation, meanwhile both CLPP and community structure were substantially influenced by NO3–N and NO2–N. Therefore, NO2-N and NO3-N accumulation in the intensive Litopenaeus vannamei culture pond might be responsible for the delayed color development in Biolog EcoPlates. In order to minimize the influence of aquaculture water on color development in Biolog EcoPlates, a shorter incubation period is recommended.

Prolonging the shelf life of Papaya (Carica papaya L.) using Aloe vera gel at ambient temperature

The edible coating is one of the promising aspects in the preservation of climacteric fruits like papaya. Among the various edible coating, Aloe vera gel has drawn serious attention to the scientific community as one of the promising bio-preservatives due to its human health benefit and antimicrobial properties. The packaging of fruits using polythene bag is already a common practice. Thus, this study was conducted to evaluate the effect of no packaging and packaging with both perforated and unperforated polythene, together with Aloe vera gel coated and uncoated papaya fruits on post-harvest ripening behaviour and physicochemical properties when stored at room condition (25 ± 2 °C temperature and 80–85 % relative humidity). The results showed that Aloe vera gel coating alone delayed colour development during storage compared to the control (no packaging without Aloe vera gel). After 12 days of storage (DAS), the weight loss and moisture content of fruits treated with only Aloe vera gel were 11.7% and 89.9% respectively, whereas in control, the weight loss was 25.2% and moisture content was 87.1%. Moreover, soluble solids concentration (SSC) and disease severity were reduced as around 3% and 29% respectively, for coated compared to uncoated fruits. Similar to Aloe vera gel coating, packaging of papaya fruits with only both types of polythene bag showed better performance compared to control but not as much as Aloe vera gel coating alone. In addition, if the fruits are coated with Aloe vera gel as well as packed with polythene bag their edible quality drastically reduces once the fruits reach their peak climacteric or ripening stage, although these results were more severe with unperforated polythene compared to perforated polythene bags. These findings also suggest that Aloe vera gel as an edible coating could be used commercially for extending the storage life of papaya fruits for up to 14 days, while packaging of Aloe vera gel-coated papaya fruits in polythene bags must be avoided during, storage, transportation, and marketing. In addition, this is in accordance with the need to avoid the use of non-recycled plastic material due to its pollution effects on ecosystems worldwide.

Modified Atmosphere Storage Extends the Shelf Life of ‘Nam Dok Mai Sri Tong’ Mango Fruit

ABSTRACT Investigation of modified atmosphere packaging (MAP) on changes of fruit quality during cold storage and shelf life extension in mango was conducted with MAP using white ethylene absorbing bag (WEB) and green absorbing bag during storage at 15°C for 30 days. The results found that the mangoes kept in WEB maintained their texture and appearance better than those in package without a plastic bag. Mangoes stored in WEB were more firm than those stored in air (normal atmosphere) during 30 days of storage and could delay the ripening and maintained the quality of the fruits, while the fruit packed without plastic bags extended the shelf life for 24 days. The MAP retarded the ripening process and delayed color development of the mango fruit compared to the mangoes without packing during the cold storage. In particular, WEB effectively reduced respiration rate and weight loss of the fruits stored at 15°C for 30 days. This MAP maintained a higher titratable acidity and firmness of peel and pulp in the mango fruits, while the activities of polygalacturonases in the pulp were reduced. Comprehensive quality analysis indicated that this MAP was the most effective method for improving the quality of mango fruits and extension of shelf life under the cold storage.

Burdock fructooligosaccharides inhibits postharvest colour development in grape skins by altering phenylpropanoid fluxes from anthocyanin to the resistance‐related phenolic substances

Background and Aims Burdock fructooligosaccharides (BFO) is an elicitor that induces biotic resistance and delays colour development in grapes postharvest. The mechanism of the delayed colour development requires further study. Methods and Results Colour development index; anthocyanin, tannin, flavonol, flavanol, trans‐resveratrol and lignin; the trans‐resveratrol, lignin and anthocyanin biosynthesis‐related transcription factors; and functional gene expression were investigated. In response to BFO induction, upregulation of the v‐myb avian myeloblastosis viral oncogene homologue 14 (MYB14)‐mediated stilbene synthase (STS) altered the phenylpropanoid fluxes from anthocyanin to trans‐resveratrol; MYBA1 and MYBA2‐mediated the downregulation of dihydroflavonol 4‐reductase (DFR), and flavonoid‐3‐O‐glycosyltransferase (UFGT) limited anthocyanin biosynthesis. Downregulation of MYB4‐mediated chalcone synthase (CHS) and upregulation of cinnamoyl CoA reductase (CCR) and cinnamyl alcohol dehydrogenase (CAD) altered the phenylpropanoid fluxes from anthocyanin to lignin. Conclusions Burdock fructooligosaccharides inhibits postharvest colour development in grapes by altering the phenylpropanoid fluxes from anthocyanin to resistance‐related phenolic substances. Significance of the Study Understanding the mechanism of the effect of BFO on grape colour development may improve our understanding of colour development in grape berries.

Enhancement of storage life and quality maintenance of plum fruits

The present study was conducted to evaluate the effect of pre-harvest application of calcium chloride at 0.0, 1.0, 1.5, 2.0% concentrations on various physico-chemical parameters and enzymatic activities in plum fruits cv. Satluj Purple at various storage intervals (0, 7, 14, 21, 28 and 35 days) under low temperature conditions. Two sprays of CaCl2 @ 1.0% were most effective in maintaining the post-harvest quality attributes and efficiently reduced the physiological loss in weight (PLW), spoilage, pectin methyl esterase (PME) & cellulase activities and significantly delayed colour development & suppressed anthocyanin formation in plum fruits up to 28 days of cold storage. At the end of storage, two sprays of CaCl2 (1.0%) recorded higher fruit firmness (54%), sensory quality (24%), higher total soluble solids (5.70%), titratable acidity (41%), total sugars (7.14%) and total phenols (13%) as compared to control.

Edible coatings influence the cold-storage life and quality of 'Santa Rosa' plum (Prunus salicina Lindell).

Plum is a perishable fruit with a very short shelf life of 3-4days. Several studies have suggested the possible use of edible coatings on maintaining quality and prolonging storage life of fresh horticultural produce. Hence, different edible coatings, namely, lac-based (2:3), Semperfresh™ (1:3) and Niprofresh® (1:5) were selected to observe their efficacy on quality retention of 'Santa Rosa' plums. The effects of these coatings on the physical, physiological and biochemical attributes were studied under cold storage conditions (2 ± 1°C and 85-90% relative humidity). Our results revealed that all the coatings, especially the lac-based significantly reduced the weight loss and maintained higher firmness throughout the storage period. These surface coatings modified the respiration and ethylene rates of the plums and slowed down their metabolism as shown by the retention of texture of the tissue and delayed colour development. At the end of 35days of cold storage, lac-based coating helped to retain nearly 55% higher fruit firmness and 21% higher antioxidant activity in fruits as compared to uncoated ones. However, the changes in total anthocyanin content were found to be suppressed by 13% in lac-based coated fruits. Overall, the results suggested that lac-based coating of plum fruits was most effective to extend the storage life of 'Santa Rosa' plums over other coatings and uncoated fruits under low temperature storage conditions.

Effect of Cold and Heat Shock Treatment on the Color Development of Mature Green Tomatoes and the Roles of Their Antioxidant Enzymes

Color is the most important marker of the quality and ripeness of tomato fruits. To study the effect of cold shock treatment (CST; 0 °C, 3 h) and heat shock treatment (HST; 50 °C, 2 min) on the color development of mature green tomatoes and the roles of antioxidant enzymes, we measured color, the levels of malondialdehyde (MDA), ascorbic acid, and antioxidant enzymes at 20 and 10 °C storage conditions. HST retarded the ripening of mature green tomatoes, delayed color development, reduced MDA content, and increased superoxide dismutase (SOD) and peroxidase (POD) activities in tomatoes stored at 20 or 10 °C, as well as increased catalase (CAT) activity in tomatoes stored at 10 °C. In comparison with controls, CST accelerated the development of senescence in mature green tomatoes stored at 20 or 10 °C, which reflects faster color development and higher MDA content, resulting from the low activities of SOD and POD. These results suggested that, with regard to the antioxidant enzymes SOD and POD, CST had a different effect on color development compared with that of HST in mature green tomatoes stored at 20 or 10 °C. Furthermore, these results implied that SOD and POD played significant roles in the antioxidant system in CST- and HST-treated mature green tomatoes stored at 20 or 10 °C, and CAT was the crucial antioxidant enzyme to resist cold storage in HST-treated mature green tomatoes stored at 10 °C.

Reduced chilling injury and delayed fruit ripening in tomatoes with modified atmosphere and humidity packaging

Abstract To prolong shelf life and reduce chilling injury of tomato, the effects of modified atmosphere packaging (MAP) on tomato were investigated using Xtend MA/MH bulk packaging (XF) and polyethylene (PE) bags during storage at 4 °C and 12 °C for 14 days and under shelf-life conditions at 20 °C. The O2 concentrations in PE bags stored at 4 °C and 12 °C were 19.9–20.3% and 20.6–20.9%, respectively, whereas those in the XF package were reduced to 14.9–16.7% and 17.8–18.5%, respectively. The XF package showed a higher CO2 content (4.2–7.3%) than PE (0.5–1.2%) packages stored at 4 °C and 12 °C. Relative humidity (RH) was saturated within the PE bags but not within XF after 7 days of storage. MAP retarded the ripening process and delayed colour development compared to the non-packaged control during cold storage. In particular, XF effectively reduced the pitting score and decay rate of fruits stored at 4 °C for 14 days and transferred to 20 °C for 3–8 days, and increased gene expression of protease inhibitor II and catalase. Enhanced CO2 and reduced O2 levels and optimal RH (95%) provided by modified atmosphere and humidity could be used to reduce chilling injury and extend the shelf life of tomatoes.

1-Hexylcyclopropene in retarding tomato (Lycopersicon esculentum Mill.) fruit ripening and its mode of action

Modulation of climacteric ripening in ‘Kommeet’ tomato fruit with 1-hexylcyclopropene (1-HCP) fumigation and its mode of action was investigated. Fumigation of 1-HCP (1000nLL−1) significantly delayed (6d) and suppressed climacteric ethylene production (0.92-fold) and respiration rate (0.71-fold) as compared to the control fruit. Fruit treated with 1-HCP (1000nLL−1) showed delayed colour development (6d), reduced weight loss, soluble solids concentration (SSC), and SSC:TA (titratable acidity) ratio, and higher TA (0.67) than the control fruit. 1-HCP treated fruit exhibited higher concentration of citric, malic, fumaric, succinic and total organic acids and no significant effects on the concentration of sugars compared to control fruit. In conclusion, 1-HCP (1000nLL−1) fumigation delayed and suppressed ethylene production, respiration rate, colour development and ripening in ‘Kommeet’ tomato fruit. 1-HCP is an effective anti-ethylene compound but its mode of action is similar to 1-methylcyclopropene (1-MCP).

Enzymatic changes in plum (Prunus salicina Lindl.) subjected to some chemical treatments and cold storage.

The objective of the present work is to see the effect of different chemical treatments on pectin methylesterase (PME) activity and softening of the fruits. Purple plums (cv. Satluj) fruits were harvested at colour break stage and treated for 5- minutes in aqueous solutions of salicylic acid at 138, 276 and 414ppm, Ascorbic acid at 10,000, 20,000 and 30,000ppm, and Gibberelic acid at 20, 40 and 60ppm. For control the fruits were dipped in distilled water. Treated fruits were stored at low temperature conditions for 40days. Physico chemical characteristics and PME activity were determined at 10day interval. The colour of the fruits improved with respect to a* and b* values progressively throughout the storage, whereas, fruit firmness decreased. Total sugars and PME activity increased before showing a declining trend. Pre-storage application of salicylic acid (414ppm) significantly delayed colour development. Fruits treated with salicylic acid (414ppm) retained highest firmness, total sugars and PME activity at the end of storage.

Banana MaMADS Transcription Factors Are Necessary for Fruit Ripening and Molecular Tools to Promote Shelf-Life and Food Security.

Genetic solutions to postharvest crop loss can reduce cost and energy inputs while increasing food security, especially for banana (Musa acuminata), which is a significant component of worldwide food commerce. We have functionally characterized two banana E class (SEPALLATA3 [SEP3]) MADS box genes, MaMADS1 and MaMADS2, homologous to the tomato (Solanum lycopersicum) RIN-MADS ripening gene. Transgenic banana plants repressing either gene (via antisense or RNA interference [RNAi]) were created and exhibited specific ripening delay and extended shelf-life phenotypes, including delayed color development and softening. The delay in fruit ripening is associated with a delay in climacteric respiration and reduced synthesis of the ripening hormone ethylene; in the most severe repressed lines, no ethylene was produced and ripening was most delayed. Unlike tomato rin mutants, banana fruits of all transgenic repression lines responded to exogenous ethylene by ripening normally, likely due to incomplete transgene repression and/or compensation by other MADS box genes. Our results show that, although MADS box ripening gene necessity is conserved across diverse taxa (monocots to dicots), unlike tomato, banana ripening requires at least two necessary members of the SEPALLATA MADS box gene group, and either can serve as a target for ripening control. The utility of such genes as tools for ripening control is especially relevant in important parthenocarpic crops such as the vegetatively propagated and widely consumed Cavendish banana, where breeding options for trait improvement are severely limited.

English

The aim of this study was to evaluate the concentrations of sodium nitroprusside (SNP), a nitric oxide donor, on postharvest ripening and quality of mango fruit cv. Nam Dok Mai No.4. The fruits were dipped in 1 or 2 mM of SNP solution for 30 min while control fruits were dipped in tap water for 30 min. After treatment, all fruits were stored for 18 days at 13°C and RH 90%. Both SNP doses showed significantly reduced ethylene production and respiration rate, maintained the fruit firmness, decreased the changes in total soluble solids and titratable acidity, and reduced fruit weight loss. The treatments of SNP also delayed color development in fruit peel and pulp. SNP-treated fruits showed higher L* and hue angle values and lower a* and b* values in comparison with control fruits. No significant differences were found between 1 and 2 mM SNP treatments. SNP applying on dose of 1mM to postharvest ‘Nam Dok Mai No.4’ mango fruits and then stored at 13°C changed ethylene production and respiration rates, maintained firmness pulp, decreased weight loss and slowed the changes in fruit peel and pulp color, total soluble solids (TSS) and titratable acidity (TA). Key words: Mangifera indica L., sodium nitroprusside, biochemical changes, fruit quality.

APPLICATION OF NITRIC OXIDE TO EXTEND THE SHELF LIFE OF MANGO FRUIT

Nitric oxide (NO), a highly reactive free radical gas, has been used as a postharvest treatment to delay fruit ripening and senescence. NO inhibits ethylene production and extends the shelf life of various fruit. The objective of this research was to determine the effect of sodium nitroprusside (SNP), a NO donor, on the quality of mango fruit during storage. Uniform and unblemished mango fruit cv. Nam Dok Mai Si Thong were soaked in 0.5 or 1 mM of SNP for 10 min; dipping in water for 10 min served as the control. After treatment, all fruit were stored at ambient temperature (22°C). Both SNP concentrations significantly reduced ethylene production and respiration rate. Only 1 mM SNP maintained firmness and delayed the changes in soluble solid content and titratable acidity. SNP also delayed color development of the pulp, with fruit treated with 1 mM SNP showing the highest L* and hue angle values and lowest a* and b* values. However, SNP had no effect on weight loss compared to the control. The results indicate that SNP treatment at 1 mM for 10 min can be used to maintain quality and extend shelf life of ‘Nam Dok Mai Si Thong’ mango fruit.

Effect of a Novel Edible Composite Coating Based on Gum Arabic and Chitosan on Biochemical and Physiological Responses of Banana Fruits during Cold Storage

The composite effects of gum arabic (GA) (5, 10, 15, and 20%) and chitosan (CH) (1.0%) on the biochemical and physiological characteristics of banana fruits stored at 13 ± 1 °C and 80 ± 3% relative humidity (RH) for 28 days and afterward for 5 days at simulated marketing conditions (25 °C, 60% RH) were investigated. Significant (P ≤ 0.05) differences were observed for the entire GA plus CH treatments as compared to the control. However, the results showed that after 33 days of storage, the weight loss and soluble solids concentration of fruits treated with 10% GA plus 1.0% CH composite coating were 24 and 54% lower, whereas fruit firmness, total carbohydrates, and reducing sugars were 31, 59, and 40% higher than the control, respectively. Furthermore, the composite edible coating of 10% GA plus 1.0% CH delayed color development and reduced the rate of respiration and ethylene evolution during storage as compared to the control. Similarly, sensory evaluation results also proved the effectiveness of 10% GA plus 1.0% CH composite coating by maintaining the overall quality of banana fruits. Consequently, the results of scanning electron microscopy also confirmed that the fruits coated with 10% GA plus 1.0% CH composite edible coating had very fewer cracks and showed a smooth surface. These findings suggest that 10% GA plus 1.0% CH as an edible composite coating can be used commercially for extending the storage life of banana fruits for up to 33 days.

Physico−chemical, respiratory and fungicide residue changes in wax coated mandarin fruit stored at chilling temperature with intermittent warming

Influence of chilling temperature, intermittent warming (IW) and fungicidal wax coating was evaluated during storage of 'Nagpur' mandarins (Citrus reticulata Blanco). Fruits were light green coloured with slight colour-break at the start of storage. Waxed and non-waxed fruits were stored at 3.5°C (constant), 2weeks at 3.5°C followed by IW for 1week at 19.5°C (cycle) and at 6.5°C (constant), and were evaluated immediately after 30, 45, 60, 75days and also after 1week holding at ambient condition (24 ± 2°C, 60-70% RH). There was no chilling injury to fruit under IW treatment irrespective of coating. At 3.5°C (constant) chilling injury appeared after 45days during 1week holding and thereafter increased at each storage interval. Wax coated fruit had lower chilling injury. Fruit under IW treatment and at 6.5°C (constant) developed yellow-orange colour while at 3.5°C (constant) fruit remained green during storage. Juice content, titratable acidity and ascorbic acid contents were not affected by temperature regimes and waxing while total soluble solids content was higher with IW treatment. Reducing and total sugars were higher in fruits stored at IW treatment and at 6.5°C (constant) than at 3.5°C (constant). Total peel phenols content were not significantly affected by waxing and temperature regimes. However, loss of phenols content was higher at 3.5°C (constant). Phenol content decreased during storage. At 3.5°C (constant), chlorophyll ('a', 'b' and total) content in peel was maximum while total carotenoids were minimum with little colour development. Rapid colour development was recorded under IW and also at 1week holding. Wax coating delayed colour development at 3.5°C (constant). Initially carbendazim residues were higher in peel (4.0ppm) and pulp (3.2ppm) of waxed fruit than in non-waxed (3.2ppm in peel and 3.1ppm in pulp) fruit. Overall drop in residues till storage up to 75days+ 1week over the initial values was 80.2-85.6% in peel and 56.2-75.8% in pulp of waxed and non-waxed fruit, respectively. Respiration was lower in waxed fruit. Respiratory rate was lowest at 3.5°C (constant) and it changed with IW. At 3.5°C and 6.5°C (constant), range of respiration was 4-6mgCO2/kg/h and 7-9 mgCO2/kg/h, respectively in waxed and non-waxed fruit. Respiratory rate increased as the fruit was removed to warmer temperature. Chilling injury caused considerable rise in respiration rate of fruit. Present findings indicated that storage life of 'Nagpur' mandarin can be extended up to 75days at 3.5°C with IW.

Fruit quality in ‘Cripp's Pink’ apple, especially colour, as affected by preharvest sprays of aminoethoxyvinylglycine and ethephon

‘Cripp's Pink’ apple grown in Western Australia often develops poor colour at commercial harvest resulting in economic losses. To determine if fruit colour could be improved without advancing ripening, ‘Cripp's Pink’ apple fruit on trees were sprayed with aminoethoxyvinylglycine (AVG) alone, ethephon alone, or AVG followed by ethephon. The experiments were conducted at two different locations in Western Australia in 2002 and 2003. Fruit sprayed with AVG alone had retarded colour development at harvest. However, ethephon applied after AVG enhanced percent red blush, anthocyanin concentration and reduced chlorophyll concentration in the fruit skin in both locations. These fruit had similar colour to those treated with ethephon alone. Internal ethylene concentration and fruit firmness were unaffected by the different treatments in 2002. However, in 2003 AVG with or without ethephon reduced internal ethylene concentration and maintained firmness compared to ethephon alone. In conclusion, AVG treatment alone delayed colour development and ripening of ‘Cripp's Pink’, while AVG application 5 weeks before harvest followed by an ethephon application 2 weeks later enhanced red colour at commercial harvest. This is, therefore, an effective tool for improving colour of ‘Cripp's Pink’ apples at commercial harvest without adversely affecting other fruit quality attributes.

Influence of different concentrations of 1-methylcyclopropene and times of exposure on the quality of ‘Galia’-type melon harvested at different stages of maturity

SummaryThis study evaluated the influence of different 1-methylcyclopropene (1-MCP) concentrations (150, 300 or 450 nl l–1) applied for 6, 12 or 24 h at 20°C on ‘Galia’ type melon (Cucumis melo L., reticulatus cv. ‘Trooper’), harvested at three stages of maturity, based on epidermal colour: green (~ 116 h° [Hue angle]); green/yellow (~ 105 h°) or yellow (~ 90 h°), and stored for 15 d at 5°C then 3 d at 20°C. The optimal treatment with 1-MCP to suppress ripening of fruit harvested at the green/yellow stage of maturity was 300 nl l–1 for 24 h at 20°C, as evaluated by delayed colour development, retention of firmness, and low weight loss. This treatment also significantly reduced chilling injury (CI) and the development of decay, compared with non-treated fruit, or fruit treated with 150 nl l–1 1-MCP. However, 1-MCP did not suppress senescence in fruit harvested at the yellow stage of maturity, as evaluated by external and internal quality parameters. 1-MCP did not affect total soluble solids contents. When fruit was harvested at the green stage, 450 nl l–1 1-MCP reduced the rate of post-harvest ripening significantly, resulting in fruit of unacceptable colour development and firmness. 1-MCP delayed by 8 – 9 d the onset of the climacteric peak of CO2 production and ethylene evolution in fruit harvested at the green/yellow stage of maturity. The quantities of CO2 and ethylene production in 1-MCP-treated fruit were lower than those in controls.

Inhibiting Tomato Ripening with 1-Methylcyclopropene

The capacity for 1-methylcyclopropene (1-MCP) to inhibit color change and firmness loss and alter aroma profiles for tomato (Lycopersicon esculentum Mill.) fruit was evaluated as a function of 1-MCP concentration, multiple and continuous applications, and stage of ripeness. In addition, the relationship between external and internal fruit color and firmness was determined. 1-MCP reduced the rate of red color development in fruit of all stages of ripeness. A single application of 1-MCP delayed color development by ≈ days. A second application of 1-MCP 10 days after first treatment additionally delayed color development of mature green fruit by another 8 to 10 days. Continuous 1-MCP application completely inhibited color development of breaker and half-ripe fruit for the duration (34 days) of application, but only partially inhibited firmness loss. When fruit at 50% color development were treated with 1-MCP, gel color development tended to lag behind the external fruit color change compared to nontreated fruit. Some aroma volatiles were affected by 1-MCP applied at the mature green and breaker stages, but the effect was relatively minor; 1-MCP did not affect sugar or titratable acid levels in these fruit. Collectively, the data indicate 1-MCP caused minor shifts in the quality attributes of locule color, aroma, and firmness relative to external color, which may reduce the value of this treatment, but benefits accrued by slowed firmness loss and color development may afford sufficient compensation to make 1-MCP application commercially feasible.