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The postharvest response of two peony cultivars, 'Qi Hua Lu Shuang' and 'Da Fu Gui', to exogenous treatment with three concentrations (25, 50, and 75 μmol·L−1) of melatonin (MT) was evaluated. Both cultivars demonstrated a similar response to MT treatment in terms of delayed senescence, albeit with differing efficacies. The optimal concentration of MT (50 μmol·L−1) extended the vase life of 'Qi Hua Lu Shuang' and 'Da Fu Gui' by 1.6 and 1.2 days, respectively, relative to the control. This treatment also increased maximum flower diameter by 11.76% and 21.26%, respectively, and improved water balance, with 'Qi Hua Lu Shuang' maintaining stability for 6.0 days and 'Da Fu Gui' for 5.7 days longer than the control. Relative electrical conductivity and malondialdehyde (MDA) content, when treated with 50 μmol·L−1 MT, were reduced by 25.25% and 18.03% for 'Qi Hua Lu Shuang', and by 33.96% and 21.47% for 'Da Fu Gui', respectively. At this MT concentration, soluble sugar content peaked at 6.91 mg·g−1 FW for 'Qi Hua Lu Shuang' and 8.12 mg·g−1 FW for 'Da Fu Gui', while soluble protein content reached 5.07 mg·g−1 FW and 7.93 mg·g−1 FW, respectively. Additionally, at the same concentration of MT, the activities of antioxidant enzymes activities (SOD and CAT) were significantly enhanced. SOD activity peaked at 749.61 U·g−1 FW in 'Qi Hua Lu Shuang' and at 652.77 U·g−1 FW in 'Da Fu Gui', while CAT activity showed increases of 31.86% in 'Qi Hua Lu Shuang' and 44.46% in 'Da Fu Gui', compared to the control. These results demonstrate that 50 μmol·L−1 MT optimally delays senescence and preserves the postharvest quality of cut peonies, offering valuable insight for the floral industry. • Melatonin significantly enhances vase life and quality in two peony cultivars. • 50 μmol·L−1 melatonin optimally delays senescence in peony cut flowers. • Melatonin treatment effectively improves water balance and reduces cell membrane damage in peonies. • Melatonin treatment increases soluble sugars, proteins, and antioxidant activity, supporting flower quality. [ABSTRACT FROM AUTHOR]

Highlights • Range and duration of HHP treatment affected turgor. • A turgor of 0.1 MPa denotes a threshold for irreversible HHP-dependent effects. • HHP-dependent variations in tuber stiffness are closely related to turgor losses. • Colour changes reflect anthocyanin redistribution due to high membrane permeability. • Irreversibility resulted from combined damage of membranes and membrane proteins. Abstract The impacts of high hydrostatic pressure (HHP) treatments on metabolic functionality and quality of fruit and vegetables are still poorly understood. The effects of pressure intensity (100, 150 and 200 MPa) and holding time (5 and 10 min), and temperatures (20, 30 and 40 °C) during HHP treatment on fresh radish tubers has been studied. Colour, stiffness and turgor of the tubers were evaluated using colorimetry, texture analyses and direct turgor measurements with the cell pressure probe techniques. Comparison of turgor and stiffness losses, and colour changes, of skin and thin-walled parenchymatous inner radish tissue showed the effects of the various HHP treatment parameters on the permeability of biomembranes. HHP treatment resulted in a rapid reduction of cell turgor and, concomitantly of tuber stiffness, but also in a cellular redistribution of anthocyanins as indicated by colour changes. These responses were partially reversible up to 100 MPa applied pressure at 20-40 °C for 5–10 min, yielding a turgor threshold of 0.1 MPa. Beyond these limits, changes were irreversible, most probably due to the denaturation of membrane bound proteins such as ion channels and pumps. Overall, even short-term HHP treatments at room temperature are not suitable for sanitation by inactivating bacteria of perishable produce. [ABSTRACT FROM AUTHOR]

To improve the safety of fresh high quality convenience products, high hydrostatic pressure treatments (HHP) may provide a gentle, quality retainion alternative to traditional chemical preservation. However, information about the potential impact of HHP on metabolic functionality of fresh produce is rare; the few published studies indicate HHP has effects on physiological activity. These effects were highly product specific due to pronounced variations in both pressure sensitivity and stress responsivity. Biomembranes generally seem to be major physiological targets of HHP treatments. Cell turgor inevitably requires fully intact cell membranes. Turgor has an important impact on the fresh appearance of fresh produce, especially texture. Up to now, there is no investigation available that has directly evaluated the effects of HHP treatments on turgor of fresh vegetable tissue. In this study, the pressure probe technique was applied to comprehensively analyse the turgor of red cabbage tissue by directly measuring the hydrostatic pressure of individual cells. The effects of HHP on the cell turgor were tested at pressures ranging between 150 MPa and 250 MPa, applied for 5, 10, 15 and 20 min. As pronounced changes in pressure could result in related temperature changes, the effects of temperature (35 °C to 55 °C) on turgor was characterised separately. At 35 °C and 45 °C, leaf turgor transiently declined after HHP treatment of 150 MPa (for up to 10 min) but recovered again within 24 h; at 55 °C, however, it irreversibly dropped to near zero. The same occurred when HHP of 175 MPa or above was applied. In general, HHP treatment and temperature increases as well as the duration of treatments interactively affected cell turgor of red cabbage leaves. Critical process parameters derived for gentle application of HHP were 150 MPa at 45 °C for 10 min treatment time. [ABSTRACT FROM AUTHOR]

Highlights: [•] Transcript profiles in peach mesocarp markedly change following wounding. [•] Melting and slow melting varieties differ in their responses to wounding. [•] Polyphenol and flavonoid content and the expression of related genes are selectively affected. [•] Mechanical stress activates regulatory and signaling mechanisms. [•] Different hormone categories appear to be involved in the responses to wounding. [Copyright &y& Elsevier]

Abstract: Inadequate temperatures during the shipping and commercialization of cut tropical flowers may accelerate the senescence process and cause chilling injury, leading to symptoms that have not yet been described for Heliconia bihai. The aim of the present study was to evaluate physiological responses in cut inflorescences of H. bihai cv. Lobster Claw (LC) and cv. Halloween (HW) as well as symptoms of senescence and chilling injury. For such, changes in fresh weight, bract color (L*, a* and b*), percentage of absolute integrity (PAI) of cell membranes and leakage of potassium ions (LPI) were determined. The flowering stems were evaluated at five different intervals after harvest (0, 2, 4, 6 and 8d). A refrigerated treatment (RT) with a temperature of 6.5°C and 85% relative humidity was compared to a control treatment (CT) at room temperature of 24°C and 66% relative humidity. Both cultivars stored at 6.5°C exhibited dryness of bract tissue (symptom of senescence) and dark stains that became brownish and evolved to necrosis (symptom of chilling injury). The visual quality of inflorescences decreased with time in both cultivars maintained without refrigeration. The severity of chilling injury increased with the length of storage time in both cultivars. There was a significant reduction in the fresh weight of inflorescences in both treatments (RT and CT) and both cultivars (LC and HW). Bract color changed in both cultivars at 6.5°C. There was no change in PAI throughout the evaluation period in the inflorescences stored at room temperature, whereas those stored at 6.5°C for 6 and 8d had lower PAI values. The inflorescences in the control treatment underwent no change in LPI values, whereas those stored under refrigeration had increased LPI values after the sixth day of storage. The physiological responses of cut Heliconia flowers were influenced by storage period and temperature, as demonstrated by visual symptoms of chilling injury and senescence. [Copyright &y& Elsevier]

Hexanal vapour and intact tomatoes were used as models to assess the opportunities for control of Botrytis cinerea rots by controlled release of organic vapours. Hexanal vapour concentrations in the ranges 5–270μLL−1 were applied continuously or as a single dose at the start of storage. The postharvest microbiological, physiological and quality attributes of control and hexanal treated tomatoes were investigated during storage for 7 days at 20±1°C and ∼99% RH. Continuous hexanal exposure effectively suppressed grey mould with the minimum inhibitory concentration (MIC) being 40–70μLL−1; the single-dose treatment showed minimal antifungal activity. During continuous exposure at the MIC the fruit respiration rate was increased ∼50% and reddening was slowed. No clear trend was observed in ethylene production and treated fruit did not differ from the controls in firmness or mass loss. The controlled release of low concentrations of hexanal vapour into a packaging headspace appears a feasible mechanism for prolonging tomato storage life. [Copyright &y& Elsevier]

Abstract: This study investigated the effects of 1-methylcyclopropene and sanitizer (acidified sodium chlorite or sodium hypochlorite), treated alone or in combination, on microbial growth and quality of packaged fresh-cut cilantro (Coriandrum sativum L.). Cilantro bunches were treated with 1.5mgL−1 1-methylcyclopropene or air for 18h at 10°C. The samples were then cut and washed in tap water, 100mgL−1 sodium hypochlorite, or 100mgL−1 acidified sodium chlorite solution for 1min. The washed cilantro leaves were centrifugally dried, packaged with 29.2pmols−1 m−2 Pa−1 oxygen transmission rate film, and stored at 5°C for 14d. Results indicated that 1-methylcyclopropene significantly (P <0.0001) delayed the decrease in O2 and accumulation of CO2 partial pressures in the headspace of sample packages. Acidified sodium chlorite application significantly reduced initial coliform/Escherichia coli counts (P <0.001), and reduced decay rate at the end of storage (P <0.05). A combination treatment of 1-methylcyclopropene and acidified sodium chlorite, followed by acidified sodium chlorite treatment alone, maintained the lowest decay rates and the highest overall quality scores at the end of storage. [Copyright &y& Elsevier]

Abstract: During fruit ripening on the tree and after harvest some essential processes involve the production of the anaerobic metabolites, acetaldehyde (AA) and ethanol. These processes include the production of aroma volatiles and removal of fruit astringency. Acetaldehyde, a natural aroma component, is present in almost every fruit; it accumulates during ripening even under aerobic conditions, but to a much greater extent under partially or totally anaerobic conditions. Partially anaerobic conditions often occur during fruit ripening and under storage conditions, for example, through coating with waxes or other films, or in modified and controlled atmospheres. A requirement for anaerobic metabolites in normal ripening provided the initial indication that the application of such anaerobic metabolites might be beneficial for postharvest fruit quality. In some fruit it was found that application of ethanol or AA alone can affect fruit ripening on the tree, for example, in figs (to induce maturity), banana and persimmon (to remove astringency), and grape (to increase anthocyanins). In the postharvest period anaerobic metabolites may be applied to induce volatile production and to improve fruit aroma. In addition, it has been found that AA has fungicidal and insecticidal activity. Acetaldehyde and ethanol have been shown to be capable of retarding senescence and inhibiting ethylene production in plants, leading to less chilling injury symptoms in various fruit. However, anaerobic metabolites should be applied carefully, depending on the species and variety of the fruit. Subtropical fruit are among the most sensitive to anaerobiosis damage, but application of AA in high concentrations can be phytotoxic to all fruit. [Copyright &y& Elsevier]

Freshly cut honeydew chunks were dipped for 30 s in a solution containing 1.9 mM hypochlorous acid (ClO) without or with a 40 mM concentration of calcium (Ca) propionate, Ca amino acid chelate formulation (Ca chelate), calcium chloride (CaCl2), or not treated. Respiration and ethylene production rates, firmness, translucency, microbiological and sensory characteristics, surface color, volatile abundance, and tissue calcium content were evaluated during 7 d at 10 °C. Nontreated samples developed the highest respiration and ethylene production rates during storage, followed by samples dipped in ClO, ClO+CaCl2 or ClO+Ca chelate, and ClO+Ca propionate. Calcium salt and chelate treatments more than doubled tissue Ca content and inhibited changes in melon firmness, surface color, and the development of tissue translucency during storage. Treatment with ClO alone increased tissue translucency development, but inhibited surface microbial development. Microbial development was higher on nontreated melon samples than on ClO+Ca propionate-treated samples. Total quality-associated volatile abundance increased throughout storage and was higher in ClO+Ca propionate-treated samples than in other treated and nontreated samples. No sensorial preference was observed by consumer panels among ClO-, ClO+Ca propionate-, or ClO+Ca chelate-treated samples. The results indicate that a sanitary dip with Ca is a better alternative to a sanitary dip alone for quality maintenance and shelf-life stability of fresh-cut honeydew melon tissue. [Copyright &y& Elsevier]

Since the discovery of 1-methylcyclopropene (1-MCP) as an inhibitor of ethylene action, over 100 studies have examined details of its action, application and effects on ethylene inhibition. This plant growth regulator is a tool that can help scientists make major advances in understanding the role of ethylene in plants. 1-MCP prevents ethylene effects in a broad range of fruits, vegetables and floriculture crops. Effective concentrations are low and range from 2.5 nl l−1 to 1 μl l−1. Concentration interacts with temperature such that low concentrations of 1-MCP applied over longer durations may be as effective as high concentrations. 1-MCP is most commonly applied at 68–77 °F (20–25 °C), but can be used at lower temperatures in some commodities. Generally, treatment durations of 12–24 h were sufficient to achieve a full response. A variety of factors may need to be considered when using 1-MCP including cultivar, developmental stage, time from harvest to treatment, and multiple applications. Depending on the species being treated, 1-MCP may have a variety of effects on respiration, ethylene production, volatile production, chlorophyll degradation and other color changes, protein and membrane changes, softening, disorders and diseases, acidity and sugars. This review compiles what is known about the technological uses for 1-MCP, defines where discrepancies exist between reports, and aims to define areas requiring further study. [Copyright &y& Elsevier]