ASHS 2024 Conference

Identification of Genes Associated with the Chilling Prerequisites for Ripening in European Pear - Adwaita Parida
Effects of Cooling Delay and Harvest Maturity on ‘Gem’ Pear Internal Breakdown Development - Janet Turner
Efficacy of Ultraviolet Radiation for Control of the Mucor Rot Pathogen in Post-harvest Anjou and Bartlett Pears - Shawn McMurtrey
Preliminary Insights Into the Effects of Various Technologies of 1-methylcyclopropene (1-MCP) “AnsiP®” on Apple Fruit Quality During Shelf Life -William TC Chang
Pre-Storage Ambient Temperature Delay Reduces Lenticel Blotch by Mediating Metabolic Alteration in Cold-Stored ‘Summer Prince’ Apples - Hyowon Park
1-Methylcyclopropene from HarvestHold Fresh® impact on ‘Red Delicious’ apple during cold storage - Ozge Horzum

The pear (Pyrus communis L.) has been classified as a climacteric fruit, undergoing a ripening process characterized by a transition from system-I to system-II ethylene production. This transition denotes a change in the regulation of ethylene biosynthesis from being auto-inhibitory to auto-stimulatory process. Increased ethylene production during climacteric ripening is accompanied by a corresponding rise in respiration. Pears require chilling for ripening, and the duration of chilling necessary for ripening varies among cultivars. ‘Bartlett

‘Gem’ pear is a relatively new European pear cultivar with good fire blight resistance. Fruit can be eaten without ripening, either at harvest or upon removing from cold storage, when still crisp and juicy, or can be expected to ripen to a buttery melting texture after 30-60 days of regular-air (RA) storage (~30 °F). Although research initially indicated ‘Gem’ could be stored in RA conditions for 5 months with good quality retention, in practice ‘Gem’ storage has proved more challenging, primarily due to internal breakdown which can appear as early as 2 months after storage, either in RA or controlled atmosphere (CA) conditions. Additionally, with increasing commercial production of ‘Gem’, there is industry interest in extending storage beyond 5 months. This on-going study evaluates factors potentially influencing internal breakdown development, such as cooling delay (representing a delay of room temperature establishment at storage facility) and fruit maturity in year 1 and cooling delay and rate of controlled atmosphere (CA) establishment in year 2. In year 1, internal breakdown incidence was essentially absent for fruit harvested at 56 N flesh firmness but higher for fruit harvested at 44 N, especially where cooling was delayed. Fruit harvested at 56 N did not soften to below 18 N at 60 d storage, indicating a longer period of postharvest chilling is required for less mature fruit.

Mucor rot is caused by the pathogen Mucor piriformis, which can be responsible for severe post-harvest decay in a wide variety of commercially important fruit. There are a minimal number of fungicides that have been shown to be effective against Mucor rot. As a result, alternative methods for control of Mucor rot are currently being investigated. Ultraviolet light in the C spectrum (UV-C) is a germicidal form of radiation that has been demonstrated to kill common post-harvest pathogens. Little information is available for the effectiveness of UV-C light against M. piriformis. For this study, a Far-UV light (222-nm) and a UV-C light (265-nm) were tested for their ability to inactivate M. piriformis. The effects of three UV-C light treatments (0kJ, 10kJ, and 20kJ) were tested on Anjou and Bartlett pears that had been wound inoculated with M. piriformis. Lesion sizes were measured after five weeks in cold storage. The optimal dose required to inactivate M. piriformis in vitro in polystyrene wells with the Far-UV light was found to be 9 kJ, which, with available bulbs set at 8 cm distance, required 17 minutes of treatment. Results showed no significant effect of treatment on final lesion size for both the Far-UV light and the UV-C light. For both lights, final mean lesion sizes were larger for fruit that had been treated with the 20kJ and 10 kJ treatments when compared to the control fruit that received no UV-C treatment. Results from this study suggest that UV-C radiation in the 222-nm and 265-nm light spectrum have minimal impacts on reducing rot caused by M. piriformis in Anjou and Bartlett pears, and, given the duration of treatment required for spore deactivation, this technology may prove impractical for managing M. piriformis on other components of pear packing systems.

Various postharvest formulations of 1-MCP have been innovated to optimize its efficacy for repeated use across storage, transportation, and retail stages. For small farms or fruits destined for farmers' markets, utilizing postharvest technologies with minimal 1-MCP concentrations is pivotal. In this trial, fruit from ‘Empire’, ‘Red Delicious’, and ‘RubyFrost’ apples was obtained from Cornell orchards in Lansing NY and Cornell AgriTech orchards in Geneva NY, on October 1, 4, and 13, respectively. Fruit were transported to the postharvest laboratory at Cornell University in Ithaca NY and fruit maturity indices were assessed. After cooling the fruit overnight, three different formulations of 1-MCP (tablet - AnsiP®-G, sticker - AnsiP®-Sticker, and sheet - AnsiP®-S, LYTONE Enterprise, Inc., Taiwan) were tested. The treatments were applied to fruit packed in cardboard boxes (30×30×48 cm), each containing 4 trays, at 3 °C for 24 hours. Fruit were then transferred to 20 ⁰C for 4 weeks, and fruit quality including internal ethylene concentration (IEC), flesh firmness, soluble solid content, titratable acidity, fruit color, IAD value index for peel chlorophyll content, and fruit weight were assessed weekly. Additionally, the release dynamics of 1-MCP from tablets, stickers, and sheets were evaluated in different trial. The 1-MCP tablets outperformed other treatments in reducing IEC and maintaining fruit firmness. The effects of different 1-MCP technologies on apple fruit quality and longevity during shelf life will be discussed.

Lenticel blotch as peel physiological disorder occurs in cold-stored apple fruit, characterized by irregular shape breakdown tissue without extending to the flesh. This study aimed to evaluate the postharvest treatment effects on fruit quality attributes, mineral nutrients, targeted metabolites, and incidence of lenticel blotch, and their relationship in cold stored ‘Summer Prince’ apple fruit. Fruits were harvested from 2 orchards, treated with postharvest 1-MCP, pre-storage ambient temperature delay for 7 days (ATC), and 1-MCP ATC at harvest and then stored at 0.5 °C for 5 months. There were significant differences in the organic matter content, nitrate nitrogen (NO3-N), and phosphoric acid contents in the soil. Calcium, manganese, copper, and zinc in leaf tissues were significantly different between 2 orchards. Lenticel blotch was effectively controlled by ATC treatment, while exacerbated by 1-MCP. Based on the results of VIP scores, histidine, valine, sucrose, K/Ca ratio, (K Mg P)/Ca ratio, total phenolic compounds, total flavonoids, ABTS, and DPPH were influenced by the postharvest treatments. In the results of volcano plot analysis, ATC treatment effectively controlled the symptoms and up-regulated in amino acids, such as valine, histidine, proline, and isoleucine. However, 1-MCP treatment caused to induce lenticel blotch by upregulating aspartic acid and glutamic acid. Therefore, the results indicated that pre-storage ambient temperature delay should control the lenticel blotch by mediating targeted metabolic alteration during cold storage.

Ethylene affects the postharvest quality and storage life by affecting the physiological changes related to ripening in apple fruits. 1-Methylcyclopropene (1-MCP), a cyclopropane-derived compound, is an effective ethylene inhibitor that blocks ethylene receptors at the cellular level, preventing ethylene effects and delaying its production. Several commercial products are available that provide controlled release of 1-MCP. In this study, a new 1-MCP technology was used, which uses a polymer sheeting material coated with cyclodextrin-encapsulated 1-MCP that is released when exposed to high humidity. Red Delicious apples were commercially harvested in Elbridge, Michigan, and 1-MCP sheets were applied targeting different 1-MCP concentrations (50, 100, 1000, 4000 ppb) and were placed on top of the fruit held in vented cardboard apple boxes in an open room. Another commercial 1-MCP product, Easyfresh®, powder (EF), (Fine Americas, Walnut Creek, CA) was applied at multiple dosages (0, 5, 50, 100, 1000 ppb) to fruit in cardboard apple boxes within sealed chambers as controls. Treated and untreated apples were stored in a cold room at 0 °C temperature and >90% relative humidity. We examined changes in ethylene production, respiration rate, firmness, soluble solids, titratable acidity, weight loss, and superficial scald during 7 months cold storage. The EF treatment was more effective than the 1-MCP sheet treatment for a given target concentration. The effect of 4000 ppb 1-MCP sheet was similar to the 50 ppb EF for the first 3 months of cold storage. The lack of effectiveness of the 1-MCP from sheet was likely due to escape of the 1-MCP from the apple box and off-target sorption by the cardboard.  EF 100 and 1000 ppb concentrations resulted in the lowest ethylene production, respiration rate, weight loss, and superficial scald values in the overall study for 6 months. These concentrations were also influential in preserving firmness, brix, and titratable acidity values. 1-MCP sheet efficacy could be improved by raising the dosage target or changing the architecture and the materials of the boxes in which treatment occurred.

Microgreens are an emerging functional food that is sought after due to dense nutrient compositions as well as vibrant colors and textures. Seed contamination is one of the major food safety concerns as microgreens are consumed raw. Plant pathogenic diseases are also a concern as these can cause a reduction in the growth and quality of the crop. Seed sanitation methods should effectively reduce microbial load with minimal adverse effects on seed germination. The objective of this study was to investigate the effect of four seed sanitizing treatments on germination, shoot production and mineral nutrient concentrations of four microgreen species including chive (Allium schoenoprasum), shiso (Perilla frutescens var. crispa), scallion (Allium fistulosum) and dill (Anethum graveolens). Microgreen seeds were subject to four sanitizing treatments including: Tsunami 100 (400 ppm, 5 min), hydrogen peroxide (3%, 5 min), vinegar (1%, 15 min), and hot water (85°C, 10 sec). Seeds which were treated with deionized water for 10 min were considered to be the control. The microgreens were grown in a greenhouse and were planted into a peat-based substrate and a jute fiber mat in January 2024. Prior to greenhouse production, a germination test was conducted to investigate germination percentage of seeds for each species in response to the four sanitizing treatments or control. Microgreens were assessed for germination, shoot coverage, shoot height, fresh and dry shoot weight, and mineral nutrient concentrations. There was a significant interaction between microgreen species and the sanitizing treatment on fresh and dry shoot weight. The lowest fresh shoot weight for the three species chive, scallion and shiso was 938.2 g·m-2, 976 g·m-2, 907.8 g·m-2, respectively when treated with hot water, with the other three sanitizing treatments and control resulting in statistically similar fresh shoot weights. Dill microgreens showed little difference in fresh shoot weight among the five sanitizing treatments with values ranging from 506.4 g·m-2 in hot water to 868.2 g·m-2 in control. Sanitizing treatment and substrate type both had a significant effect on the shoot height of tested microgreens. Hot water treated microgreens produced the shortest shoots with a mean shoot height of 7.7 cm regardless of species or substrate type. The other four sanitizing treatments produced statistically similar shoot heights ranging from 8.01 cm with vinegar to 8.1 cm with Tsunami 100. The peat substrate increased overall shoot length in tested microgreens compared with jute fiber mats regardless of sanitizing treatment or species.

There are over 7,500 apple varieties grown worldwide, each with its own set of organoleptic characteristics such as flavor, texture, and appearance. However, no more than 150 varieties have been introduced broadly in the global market. Consumer preference for apples is influenced by a complex interplay of factors beyond taste. The sheer variety of apples available in the market creates a valuable opportunity for a digital app that can help consumers navigate and select the best options based on their quality trait preferences. This project, in cooperation with U.S. Apple Association, aims to ultimately develop a digital app that will recommend apple varieties based on consumer’s preferences regarding sweetness, sourness, juiciness, crispiness, flavor, color, texture, and nutrition content. Thus, we examined the relationship between various sensory and physico-chemical data to understand their significance in apple selection. Five cultivars of apples grown organically (‘Ambrosia’, ‘Cosmic Crisp’, ‘Gala’, “Sugar Bee®’, and ‘Sweet Tango’) were purchased from a retail store in Mid Atlantic area during the winter season. Thirty apples of each cultivar (n=30) were measured for volume, weight, height, width, specific density, surface area, circumference, fizziness and for skin color (L*, a*, b*, hue angle, chroma). Firmness parameters and acoustic texture parameters were also measured. Additionally, total juice content, soluble solid content (SSC), titratable acidity and pH were assessed. Consumer panels (n=45: female=22, male=23) were conducted to evaluate traits including sweetness, sourness, flavor, texture/mouth feel, and overall eating quality (OEQ) using a five-point scale. Consumers displayed a stronger preference for ‘Cosmic Crisp’ and ‘Sugar Bee®’ varieties compared to ‘Gala’ and ‘Ambrosia’. This preference is driven by significantly higher consumer ratings for firmness, sweetness, and sourness of ‘Cosmic Crisp’ and ‘Sugar Bee®’. As highlighted in previous studies, correlations between consumer-rated sensory scores and their corresponding instrumental measurements were low. Furthermore, OEQ showed a stronger correlation with sensory ratings (r=0.54-0.84 ) than instrumental measurements (r=0.02 to 0.49). This suggests that consumer evaluation is critical, and may be a more reliable indicator, for the development of a digital app, compared to instrumental measurements. An accompanying consumer survey (n=30) indicated that crispness is a key factor considered by consumers when choosing apples. This project provided valuable insights and potential issues when developing a user-friendly app for consumers. It identified the dominant factors influencing apple selection and showed methods to cross-validate sensory ratings with corresponding instrumental measurements.

Visual quality is an important factor for consumer purchasing decisions of fresh-cut lettuce. Consumer behavior towards produce quality has been studied via traditional human evaluations. For sensory studies, quality evaluations are commonly done by trained human panels and consumer panels. This study was to investigate the possibility of replacing human evaluation with a machine based approach, using image capturing and analysis, and determine whether efficiency of produce quality analysis can be enhanced. Three types of data were collected: (a) consumers’(n=200) evaluation of lettuce on the picture, (b) instrumental analysis of samples (package head-space gas composition (O2, CO2) and electrolyte leakage), (c) image analysis of lettuce on the pictures. For image analysis, ImagePro’s smart segment tool was used to classify the lettuce samples into five regions: adult leaf, baby leaf, rib, rib degradation, and leaf degradation. This was used to find and calculate L*a*b, hue angle, chroma values, area, and relative area of these regions. Lettuce samples consisted of four cultivars (Green Forest, King Henry, Parris Island Cos, PI 491224). Samples were measured on day 7, 10, and 13 of storage. To predict browning score, data sets (b) and (c) were fed into a regression algorithm. The scores assigned by trained panels served as the target variables. The results showed a strong correlation between consumer’s browning score on the pictures and predicted scores generated by the regression model (r=0.74). Interestingly, removing the instrumental data set (b) did not worsen the model’s performance. The model achieved an R2 of 0.92 and RASE of 8.90 when using trained data sets (a) and (c), and an R2 of 0.91 and RASE of 8.53 when using trained data set (c) only. While a correlation coefficient of 0.74 indicates a promising relationship between image analysis and human evaluation of browning score, it’s not sufficient to definitively replace human evaluation. Further studies with larger datasets and exploration of more advanced machine learning models could lead to a more robust statistical model.

Ethylene Degreening: A Technique to Enhance Peel Color of Georgia-Grown Satsuma (Citrus reticulata) Citrus Fruit - Taiwo Owolanke
Postharvest Storage Temperatures to Promote Anthocyanin Accumulation and Antioxidant Activity in Blood Orange cv. Moro - Fariborz Habibi
Preserving Flavor in Grapefruit Juice: Continuous Flow High-Pressure Homogenization Versus Conventional Treatment - Jayashan Adhikari
Effects of Alternative Atmosphere Storage on the Postharvest Quality of Georgia-grown Blackberries - Ramsey Corn
Examining the Effect of Storage Temperatures on Chilling Injury Incidence of Georgia-Grown Peaches - Orestis Giannopoulos
Postharvest melatonin application maintains quality of jackfruit bulbs by alleviating enzymatic browning and oxidative stress under low temperature storage - Jashanpreet Kaur
Catalysis of 1-Methylcyclopropene Degradation By Non-Target Materials: Metals and Metal Salts - Ozge Horzum

In recent years, the production of Satsuma oranges (Citrus reticulata) has significantly increased in the state of Georgia. Satsumas are known to develop a deep orange peel color naturally when the temperature drops below 12°C at night. However, due to the subtropical climate of South Georgia, the fruit often fails to turn orange naturally even after attaining physiological maturity standards. Consumers tend to choose fruits based on appearance, with brightly colored oranges being more likely to attract buyers. Degreening is a postharvest technique that utilizes gaseous ethylene (C2H4) to accelerate and promote the development of orange/yellow color pigments in fresh-market citrus fruit. The study was conducted using four Satsuma cultivars ('Brown Select', 'Owari', 'Miho', and 'Xie Shan') harvested at physiological maturity yet with green peel coloration. The fruit samples were subjected to a degreening treatment which involved exposure to a continuous flow of

Blood oranges (Citrus sinensis L. Osbeck) fruit contain valuable compounds for human health, including anthocyanins, flavonoids, polyphenols, hydroxycinnamic acids, and ascorbic acid. Anthocyanin is considered an important internal quality index of blood oranges due to its red color and antioxidant activity. Blood orange pigmentation under similar growing conditions depends on some factors including cultivar, cultural practices, soil characteristics, climate conditions, maturity, and harvest maturity. Blood orange fruit require cold temperatures between 8 °C to 15 °C during the last ripening stages to develop high levels of anthocyanin in their flesh. However, commercial production of blood oranges in subtropical or tropical regions is limited due to very low or lack of cold temperatures to enhance anthocyanin concentration in fruit. We evaluated the effect of different storage temperatures (10, 15, and 20 °C) on anthocyanin enhancement and the antioxidant activity of ‘Moro’ blood orange for 42 days. Fruit were harvested from a commercial citrus orchard in south Georgia and transported to the postharvest lab in Gainesville, Florida. Fruit were checked for absence of defects andr rind injuries, sanitized with 100 ppm sodium hypochlorite solution, and superficial water removed from the fruit surface. The fruit were then divided into sets of four replicates of 10 fruit per treatment and placed in mesh bags for storage at 10, 15, or 20 °C with 90 % relative humidity. Anthocyanin accumulation and antioxidant activity in the flesh were evaluated every 14 days for 42 days. There were significant differences among the applied storage temperatures for anthocyanin content and antioxidant activity. The highest anthocyanin concentration and antioxidant activity were observed at 10 °C, while the lowest anthocyanin level was at 20 °C for all sampling times. The efficiency of these temperatures in enhancing flesh anthocyanin and antioxidant activity was in the following order: 10 °C > 15 °C > 20 °C at all sampling times. Overall, it can be concluded that cold storage can be used as a simple technology for enhancing bioactive compounds and antioxidant activity in blood oranges that are poorly pigmented at harvest in subtropical or tropical climates like Florida.

Grapefruit is known for its citrus aroma and tangy flavor. Processors use post-harvest preservation methods for juice production to maintain quality during storage for market distribution. These processes aim to preserve quality and safety while reducing unwanted compounds such as furanocoumarins. However, traditional methods like thermal pasteurization alter sensory quality and nutrient contents. With consumers demanding fresh-like taste without safety issues, researchers have aimed to develop new processing technologies. Here, we tested continuous flow high-pressure homogenization (CFHPH) for grapefruit juice processing. This method may extend shelf-life while maintaining fresh-like flavor. In this study, CFHPH was applied at various pressure levels (200, 250, 300 MPa), inlet temperatures (4 or 22 °C), and a flow rate of 1.125 L/min, and compared with conventional high-temperature short time (HTST) processing for preserving flavor compounds in Ruby Red grapefruit juice during storage at 4 °C for 45 days. Gas chromatography–mass spectrometry analysis identified key volatile compounds such as limonene, myrcene, α-pinene, β-pinene, and linalool. CFHPH preserved flavor compounds better than HTST, while HTST treatments led to flavor loss and off-notes. CFHPH maintained major volatiles like limonene, suggesting its potential as a consumer-preferred preservation method. This research underscores the significance of innovative techniques for maintaining grapefruit juice sensory quality, which is essential for customer satisfaction and market success.

Blackberries have several susceptibilities that contribute to the fruit’s high perishability resulting in a short shelf-life. The industry-standard technique for maintaining the postharvest quality is to store berries in a room with low temperature and high relative humidity to slow senescence. Despite the use of cold storage, the shelf-life of fresh-market blackberries can be short, limiting their marketing potential. The application of innovative technologies such as controlled atmospheres (CA), or the addition of gaseous ozone (O3) to the cold storage rooms could aid in maintaining the postharvest quality. During the 2023 blackberry season, three harvests were conducted paired with a sensory survey one day after. Four blackberry cultivars (Caddo, Ouachita, Ponca, Osage) were hand-picked, field-packed, and hand-sorted before being placed into cold storage. The storage conditions included a control of cold storage (1 °C, 95% RH), cold storage with additional controlled atmosphere (10% CO2 10% O2), and cold storage with gaseous ozone (0.5 ppm). The blackberries were kept under the above storage conditions for up to 21 days, with quality assessments occurring every seventh day. Quality assessments included sensory attributes of visual quality, weight loss, color, firmness, respiration rates, red drupelet reversion (RDR) presence, anthocyanin content, titratable acidity, and total soluble solids. Significant differences between treatments were recorded in fruit firmness of Caddo and Ouachita berries after seven days of storage. The CA and ozone treatments resulted in higher firmness of Caddo berries compared to the control. The CA and ozone treatments resulting in lower firmness of Ouachita berries compared to the control. RDR was separated by presence of RDR with the parameters none, low, and high. In each harvest, Ouachita had the highest presence of RDR after harvest compared to the other cultivars. Caddo exhibited low to no RDR in each harvest initially and after storage. Caddo was favored by panelists in the sensory survey related to the overall flavor and overall appearance. The experiment will be repeated during the 2024 blackberry season to evaluate the above cultivars’ aroma volatile compound levels using a GC/MS system.

Peaches are climacteric fruit that can continue ripening after harvest. When stored at elevated temperatures, peaches exhibit higher respiration rates and increased ethylene production, which makes low-temperature storage key for quality preservation. Cold storage slows down metabolic activities responsible for senescence. However, temperatures between 36 and 46°F (2.2-7.7°C) might induce a disorder commonly known as chilling injury, hence, this range has been named by many scientists as the “killing zone”. The disorder is detrimental to peach quality as it affects the flesh texture, appearance, and fruit juiciness overall. Depending on the severity, peaches might not show external symptoms of the disorder which usually appears after transfer to ambient conditions. Factors such as varietal differences, storage durations, and growing conditions may influence the severity of chilling injury symptoms. Very little research has been done in the Southeast regarding chilling injury incidence, while many of the newer cultivars have never been investigated. This project aimed to investigate the appearance of chilling injury symptoms in important peach cultivars grown in the Southeastern United States. Peaches were stored at five different temperatures of 33, 36, 41, 46, and 50°F (0.5, 2.2, 5, 7.7, and 10°C) and 95% relative humidity for up to four weeks. Quality evaluations occurred on days 0, 7, 14, 21, and 28 after harvest, which were followed by three days of ambient storage to allow for the development of chilling injury. Quality measurements included weight loss, decay incidence, total soluble solids, titratable acidity, firmness, as well as visual appearance. Results show that 33°F storage temperatures had lower respiration. Higher storage temperatures of 41, 46, and 50°F resulted in increased weight loss and lower firmness readings. Peaches stored at 33 and 36°F were juicier until the 21st day of storage. All tested temperatures were tolerated for a storage period of 7 days, with no visible symptoms. On the other hand, storage durations longer than 14 days at temperatures of 36, 41, and 46°F showed the highest chilling injury incidence. More research is currently underway in order to create a map of chilling injury tolerance across different cultivars that are important for the Southeastern region.

Jackfruit bulbs are susceptible to postharvest browning which is a major factor limiting shelf life and marketability. In this investigation, the impact of postharvest melatonin (MLT) application on enzymatic browning and antioxidant metabolism in jackfruit bulbs was evaluated. Jackfruit bulbs were dipped in different concentrations of MLT (0, 0.05, 0.1 and 0.2 mmol L-1) prior to cold storage at 4 ± 1 °C temperature and 85-90% relative humidity over the duration of 20d. MLT application considerably delayed the process of senescence as demonstrated by a reduction in browning index and softening of bulbs with 0.1 and 0.2 mmol L-1 MLT application, respectively. At the end of the storage period, 0.2 mmol L-1 MLT treatment significantly maintained higher ascorbic acid (46.9 %), total phenolics (22.3%) and total carotenoids (26.3%) compared to control. Whilst 0.1 mmol L-1 MLT application curtailed fruit weight loss (46.0%) and improved total flavonoid content (16.7 %) and DPPH radical scavenging activity (12.5%) as compared to the control. The levels of polyphenol oxidase and guaiacol peroxidase were significantly lower in 0.1 mmol L-1 and 0.2 mmol L-1 MLT treated bulbs, respectively. The activity of antioxidant enzymes including catalase, superoxide dismutase, and ascorbate peroxidase was improved with the application of 0.2 mmol L-1 MLT. In addition, all MLT treatments effectively reduced malondialdehyde, lipoxygenase and hydrogen peroxide radicals. These findings suggest that dip treatment of MLT (0.1 and 0.2 mmol L-1) effectively lessen flesh browning along with maintenance of antioxidant potential and postharvest quality of jackfruit bulbs.

1-Methylcyclopropene is a cyclic olefin that inhibits ethylene action and is released as a gas from a formulated cyclodextrin. Different concentrations of 1-MCP are used globally in the fruit industry to enhance the preservation of quality attributes. The concentrations applied cannot be considered stable due to losses to target and non-target sites within the storage or treatment room environment. Copper is used in cooling systems because it transfers heat more efficiently than many other materials, but it is also used as a catalyst for chemical modification. So, we investigated the absorption or degradation of 1-MCP by various metals, including copper. These forms included metal bars (hot and cold-rolled steel, aluminum, galvanized metal, silver, gold, stainless steel, and brass), copper pipes (polished, oxidized, and with patina) and copper salts [covellite (CuS, copper II sulfide); eriochalcite (CuCl22H2O, copper II chloride); chalcopyrite (CuFeS2, copper iron sulfide); cupric carbonate (CuCO3, copper II carbonate); chalcocite (Cu2S, copper I sulfide), cuprite (Cu2O, copper I oxide); chalcanthite (CuSO45H2O, copper sulfate); tenorite (CuO, copper II oxide), and cupric acetate (Cu(CH3CO2)2, copper II acetate)], which possessed copper atoms at different levels of oxidation. The metal pieces had a surface area of 435 cm2, and the powders weighed 1 g. We put the materials in 480-mL glass jars and added 50 μL L−1 of 1-MCP gas to the headspace. Gas concentrations were measured at 0, 2, 4, 6, and 24 h in both humid and dry conditions at room temperature. The loss of 1-MCP was more pronounced in humid condition than in dry condition except when exposed to cupric carbonate. While covellite, eriochalcite, and chalcopyrite caused a 1-MCP loss of over 90% within 24 h in both conditions, stainless steel, aluminum, galvanized iron mesh, silver and galvanized iron yielded a 1-MCP loss below 10%. On the other hand, the impact of copper pipes on reducing 1-MCP is evident, and the reduction of 1-MCP also increases as the oxidation level of the copper increases. Based on mass spectral analysis of the headspace in the treatment chambers, the decrease of 1-MCP appears to occur by adsorption by the materials, polymerization, and disintegration into break-down products. The implications for 1-MCP reductions in commercial treatment rooms will be discussed.