Ethylene Peak Research Articles

Evaluating the application feasibility of thyme oil nanoemulsion coating for extending the shelf life of papaya (Carica papaya cv. Tainung No. 2) with postharvest physiology and quality parameters

Papaya (Carica papaya L.) is a typical climacteric fruit with a brief shelf life due to the rapid degradation of quality during post-ripening, necessitating appropriate postharvest management to address this challenge. This study aimed to investigate the characteristics of thyme oil nanoemulsion (TO-NE) coating and utilize its benefits for preserving papaya. This study also investigated the physiological properties and quality changes of papaya storage at 20 ℃ and, in parallel, examined the effects of TO-NE coating to mitigate microbial infection of papaya during storage. The postharvest papaya was soaked in different concentrations (0.1, 0.25, and 0.5 mg/g) of TO-NE for coating. At the same time, the decay loss rate and effective shelf life were also evaluated. This study revealed that polygalacturonase (PG) and pectinesterase (PME) activities were inhibited during the storage of papaya treated with 0.25 mg/g TO-NE coated compared to the control group. This resulted in the preservation of the firmness of papaya fruits, in addition to a higher ascorbic acid content, delayed total soluble solids (TSS) accumulation, and total chlorophyll content (TCC) degradation, with a lagging color change for two days. The respiration rate and ethylene production were suppressed, while the 0.25 mg/g TO-NE coated group at day 14 (ethylene peak) were 63.2 mg CO2 kg−1 h−1 and 7.3 µL kg−1 h−1, lower than control. The 0.25 mg/g TO-NE coating treatment significantly reduced the decay rate for 10 days of storage, preserving their appearance and facilitating ripening. This is a viable option for extending Tainung No.2 papaya shelf life.Graphical

Effects of ethephon on heartwood formation and related physiological indices of Dalbergia odorifera T. Chen

IntroductionDalbergia odorifera T. Chen, known as fragrant rosewood, is a rare and endangered tree species. Studies have shown that plant growth regulators can effectively promote heartwood formation. This study aimed to investigate the effects of ethephon (ETH) on heartwood formation and the influence of ethephon and hydrogen peroxide (H2O2) on the physiological characteristics in D. odorifera.MethodsD. odorifera branches underwent treatment with 2.5% plant growth regulators, including ETH, jasmonic acid (JA), salicylic acid (SA), abscisic acid (ABA), H2O2, and inhibitors such as ascorbic acid (AsA) to inhibit H2O2 synthesis, and (S) -trans 2-amino-4 - (2-aminoethoxy) -3-butene (AVG) to inhibit ethylene synthesis. After a 14-day period, we conducted an analysis to evaluate the impact of these plant growth regulators on elongation distance, vessel occlusion percentage, and trans-nerol content. Additionally, the effects of ETH and H2O2 on endogenous plant hormones, H2O2 content, soluble protein content, and enzyme activity were investigated within 0-48 h of treatment.ResultsAfter treatment with ETH for 14 days, the extension distance of the heartwood material was 15 cm, while the trans-nerolol content was 15 times that of the ABA group. ETH and H2O2 promoted endogenous ethylene synthesis; Ethylene content peaked at 6 and 18 h. The peak ethylene content in the ETH group was 68.07%, 12.89%, and 20.87% higher than the initial value of the H2O2 group and ddH2O group, respectively, and 29.64% higher than that in the AVG group. The soluble protein content and activity of related enzymes were significantly increased following ETH treatment.DiscussionETH exhibited the most impact on heartwood formation while not hindering tree growth. This treatment effectively triggered the production of endogenous ethylene in plants and enhanced the activity of essential enzymes involved in heartwood formation. These findings serve as a valuable reference for future investigations into heartwood formation.

Assessing the Role of Gaseous Chlorine Dioxide in Modulating the Postharvest Ripening of Keitt Mangoes through the Induction of Ethylene Biosynthesis.

Consumer acceptance of Keitt mangoes (Mangifera indica L.) is significantly affected by their slow postharvest ripening. This work used gaseous chlorine dioxide (ClO2(g)) to prepare the ready-to-eat Keitt mango and explored the potential mechanisms for the mango ripening. Harvested mangoes were treated with 20 mg·L-1 of ClO2(g) or ethephon for 3 h (25 °C) and left in a climatic chamber with a temperature of 25 ± 1 °C and a relative humidity of 85 ± 5% for 4 d. The results showed that ClO2(g) treatment significantly promoted the orange coloration of mango flesh compared to the untreated control group. Moreover, ClO2(g) treatment significantly elevated the total soluble solids, total soluble sugar, and total carotenoids content of mangoes, whereas the firmness and titratable acidity were reduced. ClO2(g)-treated mangoes reached the edible window on day 2, as did mangoes treated with ethephon at the same concentration, except that the sweetness was prominent. The residual ClO2 level of the mangoes was <0.3 mg/kg during the whole storage time, which is a safe level for fruit. In addition, ClO2(g) significantly advanced the onset of ethylene peaks by 0.5 days and increased its production between days 0.5 and 2 compared to the control group. Consistently, the genes involved in ethylene biosynthesis including miACS6, miACO1, and miACO were upregulated. In sum, ClO2(g) can be a potential technique to reduce the time for harvested mango to reach the edible window, and it functions in modulating postharvest ripening by inducing ethylene biosynthesis.

GABA primes defense responses against Botrytis cinerea in tomato fruit by modulating ethylene and JA signaling pathways

This research set out to investigate the potential action mechanism of γ-aminobutyric acid (GABA) in the control of Botrytis cinerea (B. cinerea) in tomato fruit. The findings confirmed that 10 mM GABA treatment effectively lowered the disease incidence and lesion diameter of tomato fruit caused by B. cinerea. Meanwhile, GABA treatment maintained lower electrical conductivity, color change index and lycopene content. GABA alone had little effect on most disease resistance indexes, but it triggered faster and stronger defense responses after B. cinerea infection. These responses included increases in total phenolics and flavonoids accumulation as well as the activities of chitinase (CHI), β-1,3-glucanase (GLU), phenylalanine ammonia lyase (PAL), polyphenol oxidase (PPO), and up-regulated expression of the pathogenesis-related genes (SlPR1, SlPR2a, SlPR2b, SlPR3a, SlPR3b and SlPR-STH2). Furthermore, GABA inhibited the expression of key synthesis genes of ethylene (SlACS2, SlACS4 and SlACO1) and the accumulation of a key metabolic intermediate 1-Aminocyclo-propane-l-carboxylic acid (ACC) in non-infected fruit, leading to a slight reduction in ethylene production. However, it also reduced the ethylene burst carried on by B. cinerea infection at the early storage and restored the ethylene peak at the end of storage. Furthermore, GABA up-regulated the expression level of SlERF6 directly but induced the up-regulation of SlERF2, SlERF.A4, SlERF.B12, SlERF.C6 and SlERF.H9 in a primed manner. In addition, GABA pretreatment markedly enhanced jasmonic acid (JA) content by activating the transcription of JA biosynthetic genes (SlLoxD, SlAOC and SlOPR3), up-regulated the downstream receptor gene SlCOI1 and down-regulated the suppressor gene SlJAZ2. These results demonstrated that tomato fruit treated with GABA can efficiently enhance resistance against B. cinerea through defense priming, and ethylene and JA signaling pathways are involved in this process.

Variations of quality and volatile components of morels (Morchella sextelata) during storage

The postharvest senescence of morels was observed to be easily affected by temperature fluctuations. The objective of this study was to examine the influence of various storage temperatures on the postharvest senescence of morels. The study evaluated the variations of water content, respiration, nutrients substances, cell membrane permeability, and volatile compounds in morels stored at 20 °C and 4 °C. Results showed that low-temperature storage suppressed the loss of water and firmness, delayed the time of respiration and ethylene peak, and reduced the loss of nutrients and cell membrane permeability. Furthermore, the content of volatile compounds increased and then decreased during storage. The characteristic aroma substances of 1-octen-3-ol were identified using odor activity values and OPLS-DA analysis. The study observed a decrease in the content and changes of aroma compounds during low-temperature storage. This decrease may be attributed to the decreased activities of lipoxygenase (LOX) and alcohol dehydrogenase (ADH).

A complex network regulating malate contents during fruit ripening in climacteric fruits.

This article is a Commentary on Wang et al. (2023), 239: 1014–1034.

Efeitos de concentrações de etileno e temperaturas na climatização de bananas de regiões subtropicais

ABSTRACT: Brazil is one of the largest banana producers and despite overall adequate climatic conditions to produce good quality fruit, postharvest handling procedures still are inappropriate. Only a few growers have degreening facilities at their groves. Mostly, bananas are prepared for the market by distributors. Two banana cultivars: Grande Naine (group AAA) and Prata Anã (AAB) were harvested from commercial groves and immediately submitted to degreening procedures in which three temperatures and four ethylene concentrations were evaluated. Bananas were degreened at 24 hour intervals at 13, 17 and 21 ºC with a commercial ethylene source (Banasil®) from which 12.5, 25, 50, and 100mL were placed in an ethylene generator. During the degreening process, ethylene concentrations in the degreening room were monitored for periods up to 6 hours. At the beginning of the degreening process and after three and five more days, epidermal color and pulp firmness were determined. Ethylene concentrations did not influence color changes and ripening processes of both cultivars. A maximum ethylene concentration (1,350 µL L-1) was determined in the degreening room when 100 mL of Banasil® was used at 21ºC. Even with the lowest Banasil® amount, a 90 µL L-1 ethylene peak was determined in the degreening room, enough to ripen adequately both cultivars. Degreening at 13 ºC delayed for two days the ripening of ‘Grande Naine’ bananas. ‘Grande Naine’ reached the fully ripe stage in four days while ‘Prata Anã’ completed ripening after three days. ‘Prata Anã’ bananas are more responsive to ethylene degreening than ‘Grande Naine’ bananas.

Pulsed light influences several metabolic routes, delaying ripening and improving the postharvest quality of acerola

• Pulsed light reduced acerola climacteric respiration and delayed ethylene peak. • Pulsed light-treated acerola was firmer and lost less weight. • Pulsed light enhanced polyamines by stimulating synthesis and inhibiting degradation. • Pulsed light increased vitamin C by reducing degradation and improving recycling. This study investigated how pulsed light (PL) postharvest treatment influences acerola ripening physiology and quality, thus physiologically mature acerola ‘Okinawa’ were treated with PL (0.6 J.cm −2 ) and stored for 16 days at 10 °C. Compared to untreated, PL-treated acerola showed a 5% reduction in climacteric respiration with 78.65 mol CO 2 kg −1 h −1 and a one-day delay in ethylene peak of 2.65 µL C 2 H 4 kg −1 h −1 . PL-treated acerola also showed 13% lower weight loss and was 12% firmer probably due to the enhanced antioxidant enzymes that reduced hydrogen peroxide content with lower membrane lipid peroxidation, in addition to inhibition of cell wall hydrolysis. The higher polyamine levels induced by PL may be explained by the greater synthesis, inhibition of degradation, and enhancement of back-conversion reactions. PL treatment would have increased the total vitamin C by 33% as a result of lower degradation and more efficient recycling reactions, while polyphenols would have increased 10% by reducing oxidation and enhancing synthesis. Although the storage period exerted the main influence on ‘Okinawa’ acerola, results indicate that PL delayed ripening and promoted quality as an elicitor of antioxidant metabolism thus representing a hormetic phenomenon. Proposed mode of action of pulsed light (0.6 J.cm −2 ) on the physiology of ‘Okinawa’ acerola.

1-Methylcyclopropene (1-MCP) treatment differentially mediated expression of vacuolar processing enzyme (VPE) genes and delayed programmed cell death (PCD) during ripening and senescence of apple fruit

• 1-MCP reduced VPE activity and delayed vacuolar-mediated PCD in apple fruit. • MdVPE s had varying expression patterns in response to 1-MCP during ripening. • MdVPE s were differentially expressed after transient over-expression of MdERF2. The main purpose of this research was to evaluate the impacts of 1-methylcyclopropene (1-MCP) treatment on vacuolar processing enzyme ( VPE ) genes and programmed cell death (PCD) during ripening and senescence of apple fruit ( Malus × domestica Borkh.). The ethylene antagonists 1-MCP (1 μL L −1 ) was applied to apples after harvest. Both treated and control fruit were stored at 20 ± 2°C. The data showed that 1-MCP treatment maintained flesh firmness, delayed climacteric peaks of respiration and ethylene, reduced VPE activity, relative electrical conductivity (REC), malondialdehyde (MDA) content and reactive oxygen species (ROS) accumulation during ripening. Transmission electron microscopy (TEM) and DNA ladder assay revealed that 1-MCP delayed vacuolar-mediated PCD in ripening apple fruit. Generally, expression of MdVPEγ1, MdVPEγ2, MdVPEδ4 and MdVPEδ7 was down-regulated by 1-MCP treatment, while expression of MdVPEα4 and MdVPEβ2 was enhanced by it during ripening compared with controls. 1-MCP treatment differentially reduced expression of MdVPEα1, MdVPEα2 and MdVPEα5 at the early ripening stage but promoted their expression at the late ripening stage, while it had the opposite effects on MdVPEβ1, MdVPEβ3 and MdVPEγ4 expression. After transient overexpression of MdERF2, MdVPEs displayed varying expression patterns, among which MdVPEα2 transcripts increased greater than the other genes. Our results indicated that MdVPEs expression and vacuolar-mediated PCD were mediated by ethylene signal during ripening and senescence of apple fruit.

Physiological Study of Ethephon- and ACC-Induced Fruitlet and Leaf Abscission in Peach Trees Under Different Conditions of Temperature

The effect of temperature on the ability of 2-chloroethylphosphonic acid (ethephon, ETH) and the 1-aminocyclopropane carboxylic acid (ACC) to induce ethylene production in fruitlets and abscission of fruitlets and leaves when applied at postbloom (~15 mm fruit diameter) was studied using 5-year-old ‘Sweet Lady’/Rootpac-20 peach [Prunus persica (L.) Batsch] trees kept in pots in environment-controlled growth rooms. ETH at 150 mg L−1 and ACC at 500 mg L−1 effectively thinned peaches. Increasing the temperature from 10 to 20 °C pronounced the ETH-induced fruit and leaf abscission and the ACC-induced leaf abscission and decreased stomatal conductance in leaves. However, the ACC thinning effect was not affected by increasing temperature, as well as ETH- and ACC-induced ethylene production in fruitlets and in the quantum yield of PSII photochemistry. Changes in ethylene peak in fruitlets and stomatal conductance in leaves were related to the abscission response.

Synergistic and antagonistic effects of preharvest salicylic acid and postharvest 1-methylcyclopropene treatments on the storage quality of apricot

Preharvest salicylic acid (SA, 1 mmol/L) spraying at 72 and 74 days after complete bloom combined with postharvest 1-methylcyclopropene (1-MCP, 1 μL L-1) fumigation was conducted to improve the storage quality of apricot. The results showed that preharvest SA combined with postharvest 1-MCP (SA + 1-MCP) treatment delayed the ethylene peak, inhibited respiration, slowed fruit softening, maintained high sugar and organic acid contents, and maintained high antioxidant capacity in apricots. SA + 1-MCP treatment produced synergistic effects on ethylene production, respiration rate, firmness, sorbitol, glucose and citric acid, but antagonistic effects on fructose, sucrose, malic acid, and total phenolic content and antioxidant capacity. In addition, SA treatment could overcome the disadvantages or enhance positive effects of 1-MCP treatment. Both synergistic and antagonistic effects of SA + 1-MCP treatment can achieve efficient preservation than individual 1-MCP or SA treatment. Thus, the SA + 1-MCP treatment may be an effective method for improving the storage quality of apricots.

Effects of Different Postharvest Precooling Treatments on Cold-Storage Quality of Yellow Peach (Amygdalus persica).

The rapid precooling of yellow peaches after harvest can minimize the tissue damage and quality deterioration of yellow peaches during postharvest storage. Refrigerator precooling (RPC), cold-water precooling (CWPC), strong-wind precooling (SWPC), fluidized-ice precooling (FIPC), and vacuum precooling (VPC) were used to precool the fresh yellow peaches. The yellow peaches after different precooling treatments were stored at 4 °C for 15 days. CWPC and RPC can effectively retard the respiration and ethylene peak production, reduce the quality loss of yellow peaches during postharvest storage, maintain the color and fruit hardness of yellow peaches, inhibit browning, maintain the contents of soluble solids, titratable acids, and ascorbic acid, increase the activity contents of superoxide dismutase (SOD) and peroxidase (POD), inhibit the decrease in the phenylalanine ammonia-lyase (PAL) activity, and delay the increase in the polyphenol oxidase (PPO) activity. The shelf life of yellow peaches with cold-water precooling and refrigerator precooling reached 15 days, which was 6 days longer than those of the VPC- and FIPC-treated samples, and 3 days longer than that of the SWPC-treated samples. Therefore, CWPC and RPC were effective methods to prolong the storage period and maintain the quality of yellow peaches during postharvest storage.

Efficacy of Hexanal Field Spray on the Postharvest Life and Quality of Papaya Fruit (Carica papaya L.) in Kenya

Papaya is a thin-skinned fruit that ripens and softens over a very short time, usually in 3 days, predisposing the fruit to physical damage and phyto-pathogen invasion even with careful handling further shortening postharvest shelf life. The objective of this study was to determine the efficacy of Hexanal, naturally occurring compound, on-farm spray, in managing the postharvest shelf life of papaya in two agro-ecological zones in Kenya. A formulation of Hexanal containing Tween 20 and ethanol was made by volume basis (v/v) and spray treatment at 1 and 2% in “Solo sunrise” and “Mountain” papaya cultivars. The experiment was a randomized block design with ninety-six plants per farm randomly selected. Spraying was applied at 30 days, 30 + 15 days, and 15 days to harvest time on mature green papaya. Control papaya fruits were sprayed with clean tap water as control. Data were collected on color changes and fruit retention on tree. The fruits were harvested when two to three yellow stripes were visible from the lower end of the fruits for postharvest analysis. Hexanal sprayed papaya fruits were retained for at least 13 days longer compared to the control fruits on tree. Hexanal treatment at 2% revealed an improved effect on managing papaya postharvest shelf life. All fruits treated with Hexanal significantly showed reduced rate of color break, softening, and enhanced extension of fruit shelf life by at least 6 days. Hexanal treatment also delayed ethylene and respiratory peaks by three days and showed no significant ( P ≤ 0.05 ) difference in the levels of total titratable acidity and total soluble solids. The results of this study indicate that Hexanal applied as a preharvest spray on mature green “Solo sunrise” and “Mountain” papaya cultivars grown in Kenya, is effective in prolonging shelf life and postharvest quality.

Chitosan oligosaccharide treatment improves quality attributes of tomato fruit stored under room temperature

Effect of chitosan oligosaccharide (COS), a natural product of low-cost and non-toxic with high biological activities, on quality attributes of tomato during post-harvest storage was investigated. Mature green tomato fruit were treated with 0.5 g L−1 COS and stored under room temperature. The results showed that COS was effective in improving fruit quality as revealed by redder color skin, higher content of nutrients such as carotenoids (lycopene and β-carotene) and vitamin C, and increased emissionb of flavor-associated volatiles (1-penten-3-one, heptanal, (E)-2-heptenal, 2-phenylacetaldehyde, 2-phenylethanol, 2-isobutylthiazole and β-ionone). The increased content of carotenoids upon COS treatment was correlated with the elevated expression levels of carotenogenic genes such as SlDXS, SlGGPS, SlPSY1, SlPDS, SlZDS, and SlLCY-B2. Moreover, COS-treated fruit exhibited accelerated occurrence of climacteric ethylene peak, enhanced ethylene production, and elevated expression of genes involved in ethylene biosynthesis (SlACS2, SlACS4, and SlACO1), perception (SlETR3), and response (E4 and E8), implying that COS might regulate fruit ripening and quality by enhancing ethylene biosynthesis and signaling. These findings help to extend our understanding of the function of COS in fruit ripening and provide a new strategy to improve tomato fruit quality during room temperature storage.

Effects of postharvest deastringency and 1-methylcyclopropene treatments on membrane permeability, membrane-degrading enzymes and their encoding genes in persimmon (Diospyros kaki, cv Mopanshi) fruit

Astringent persimmon fruit softens rapidly after harvest deastringency treatment. The purpose of this study was to understand the characteristics of membrane deterioration and its mechanism during rapid softening. The experiment included three treatments: (1) control, (2) CO2 treatment (≈100% CO2, 24 h), and (3) CO2 plus 1-methylcyclopropene (1-MCP, 1.5 μL∙L-1) treatment. CO2 treatment can effectively remove the astringency of persimmon fruit and cause a sharp drop in fruit firmness. The addition of 1-MCP was beneficial for firmness maintenance, but the process of astringency removal was delayed by one day. The fruit respiration rate and ethylene evolution rate were significantly increased by CO2 treatment, regardless of the presence or absence of 1-MCP, but the addition of 1-MCP could reduce the peak value and delay the occurrence of ethylene peaks by one day. The deastringency treatment resulted in a significant increase in membrane permeability and malondialdehyde content, and 1-MCP could significantly reduce membrane damage. CO2 treatment induced an enormous increase in LOX activity and the transcription of DkLOX3; however, 1-MCP significantly inhibited these increases. The PLD activity and DkPLDα1 expression level of the CO2-treated fruit were significantly promoted, and the addition of 1-MCP had less inhibition effect on the PLD activity and no significant inhibition on the DkPLDα1 expression. These results demonstrate that CO2 deastringency treatment could cause severe damage to the membrane integrity by promoting LOX and PLD activities and related gene expression. 1-MCP may ameliorate membrane damage mainly by inhibiting LOX activity and DkLOX3 gene expression and partly by suppressing PLDα1 expression.

Modulating climacteric intensity in melon through QTL stacking.

Fruit ripening is one of the main processes affecting fruit quality and shelf life. In melon there are both climacteric and non-climacteric genotypes, making it a suitable species to study fruit ripening. In the current study, in order to fine tune ripening, we have pyramided three climacteric QTLs in the non-climacteric genotype “Piel de Sapo”: ETHQB3.5, ETHQV6.3 and ETHQV8.1. The results showed that the three QTLs interact epistatically, affecting ethylene production and ripening-related traits such as aroma profile. Each individual QTL has a specific role in the ethylene production profile. ETHQB3.5 accelerates the ethylene peak, ETHQV6.3 advances the ethylene production and ETHQV8.1 enhances the effect of the other two QTLs. Regarding aroma, the three QTLs independently activated the production of esters changing the aroma profile of the fruits, with no significant effects in fruit firmness, soluble solid content and fruit size. Understanding the interaction and the effect of different ripening QTLs offers a powerful knowledge for candidate gene identification as well as for melon breeding programs, where fruit ripening is one of the main objectives.

Correlation and Analysis of Operating Temperature Data for Direct Olefin Conversion from Heavy Crude

Data analytics is a complex process of examining available data to reveal information such as hidden arrangements and correlations that can help enhance production or cost cutting decisions. The world’s demand and production of olefins are now higher than any other chemicals especially light olefins. This demand is supported by the fact that currently, Crude Oil-to-Chemicals (COTC) is an influential driver and a strong trend of high interest to all integrated refineries and chemical producers. Zeolite-based catalyst is a major cracking catalyst used in the industry, where Y-zeolites have progressively attracted attention as good adsorbents and stable acid catalysts, and are characterized by large, essentially spherical and internal cavities. This work focuses on analyzing operating data and correlating reaction temperatures for heavy crude to enhance the production of olefin using zeolite based catalyst. The prepared Y-zeolite was characterized for Specific surface area (SSA), total pore volume (TPV), average pore diameter (APD), and pore area (PA) according to the ASTM methods. The prepared catalyst showed a large pore diameter 211 Å and a high specific area of 425.6 m2/g, then the prepared catalyst was tested under varying conditions in a 250-mL autoclave-type reactor equipped with a stirrer, online Gas Chromatography (GC) and a gas sampling port. Different samples of crude with catalyst were tested at 380-450 °C and analysed via the online GC, where high peaks of ethylene and propylene were observed mainly at 430 °C reaching 3000 ppm wt. Moreover, the accumulative data of ethylene and propylene production from the experiments were recorded.

Carboxymethyl cellulose coating delays ripening of harvested mango fruits by regulating softening enzymes activities

The effect of carboxymethyl cellulose [(1%) CMC] was evaluated on mango fruits under storage at 20 ± 1 °C for 20 days. The CMC coating noticeably reduced weight loss and disease incidence. Application of CMC delayed climacteric peak of ethylene and respiration rate with significantly reduced relative ion leakage, malondialdehyde, superoxide anion and hydrogen peroxide content. The treated mangoes showed significantly lower L*, a*, b* and total carotenoids. The CMC treatment reduced the increase in cellulase, pectin methylesterase and polygalacturonase activity that delayed softening of mango fruits. In addition, activities of peroxidase, catalase, ascorbate peroxidase and superoxide dismutase were substantially higher in CMC-treated mango fruits. The treated fruits showed significantly lower soluble solids and higher titratable acidity which thereby reduced the ripening index of mangoes. In conclusion, CMC treatment could be considered a potential pre-storage treatment to delay postharvest ripening and to conserve the eating quality of ambient stored mango fruits.

Management of ethylene production, superficial scald and fruit quality in ‘Granny Smith’ apple using organic oils and ozonised cold storage

Ethylene management during storage of organically grown apples is challenging due to limited number of treatment and storage options that are available for organic produce. In this study the effects of fumigation with lemon and cinnamon oils on ethylene production, superficial scald incidence, and fruit quality in 'Granny Smith apples' placed in cold storage with and without application of ozone were evaluated. The fruit were fumigated with 3 µL L‑1 lemon or cinnamon oil for 24 h while untreated fruit were used as a control. Following the treatments, the fruit were put into cold storage at 0±2, with and without ozone for 100 or 150 days. After each storage period, ethylene production, superficial scald incidence, and fruit quality parameters were recorded. The fruit fumigated with lemon oil was significantly reduced climacteric ethylene peak rates after 100 and 150 days cold storage. The mean rate at which the ethylene climacteric peak developed was significantly reduced in fruit stored in ozonised cold storage compared to the peak level in fruit stored without ozone for 100 days. The climacteric ethylene peak was significantly delayed in the fruit cold stored with ozone (8.78 d) as compared to without ozone (3.89 d) following 100 days storage. Fruit firmness was significantly higher in fruit fumigated with lemon or cinnamon oil compared to control fruit for both storage times. Lemon or cinnamon oil fumigation significantly reduced superficial scald in the cold-stored fruit with or without ozone. The fruit fumigated with lemon oil or cinnamon oil following 150 days cold storage resulted in significantly higher levels of ascorbic acid and antioxidant capacity compared to control fruit. Overall, lemon oil fumigation was more effective in suppressing ethylene production in 100 and 150 day cold-stored fruit than cinnamon oil. Notably, fumigation with lemon or cinnamon oil were effective in reducing superficial scald and maintaining quality in 100 and 150 days cold-stored fruit.

Foliar Application of Salicylic Acid at Different Phenological Stages of Peach Fruit CV. 'Flordaking' Improves Harvest Quality and Reduces Chilling Injury during Low Temperature Storage.

Peaches are well-liked amongst the stone fruits in Pakistan. The peach industry faces significant losses, from harvesting to marketing. The objective of this study was to investigate the effectiveness of foliar sprays of salicylic acid (SA) on the fruit quality of peaches (cv. ‘Flordaking’) at the harvest and postharvest life or stages. Different concentrations of SA (control, 1, 2 and 3 mM) were sprayed on the plants at three growth stages of fruit, i.e., the cell division, cell enlargement and pit-hardening stages. In general, all the SA treatments improved the fruit quality at harvest and maintained higher levels of flesh firmness, titratable acidity and ascorbic acid during storage. However, fruit weight loss, soluble solid contents, membrane leakage, chilling injury, color development, disease and decay incidence and the climacteric peak of ethylene were lowered by SA treatment after six weeks of low-temperature storage. SA at a 3-mM concentration was proven to be the most effective in maintaining the quality for a longer period of time during low-temperature storage. Based on the results, it can be concluded that the application of SA at fruit development stages can improve the harvest quality and storability of ‘Flordaking’ peaches.