ASHS 2024 Conference

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.