Chilling Injury Incidence Research Articles

Melatonin and methyl jasmonate inhibited the chilling injury of postharvest pitaya fruit after cold storage by regulating the antioxidant system

ABSTRACT Chilling injury (CI) is the main physiological disease caused shelf decay of pitaya fruit after low-temperature storage. To find ways to control the chilling injury of pitaya fruit, we conducted the effects of postharvest treatment with 1.0 mmol L−1 melatonin (MT) and 0.1 mmol L−1 methyl jasmonate (MeJA) on the chilling injury of pitaya vs Zihonglong at 3 days of shelf life after storage at 2 ± 0.5°C. The results showed that both MeJA and MT promote the accumulation of antioxidants and the reactive oxygen species (ROS) metabolism, and inhibit the respiration rate and ethylene release rate, thereby reducing the incidence of chilling injury after cold storage, keeping the shelf quality of pitaya fruit and prolonging the shelf life of pitaya fruit. In summary, postharvest MeJA or MT inhibited the chilling injury of pitaya fruit by regulating the antioxidant system.

Antibacterial and anticancer activities of cardamom volatile oil and its application in food covering

Phytochemicals and bioactive compounds in medicinal plants significantly benefit human health and well-being. Cardamom essential oil (CEO) exhibits potential as a broad-spectrum antimicrobial and anticancer agent. A modified Kirby-Bauer disc diffusion technique was used to test cardamom essential oil’s antimicrobial activity and identify the inhibition zone. Staphylococcus aureus (ATCC 6538) and Bacillus cereus (ATCC6629) are two examples of Gram-positive bacteria against which the essential oil was evaluated for antibacterial activity. Gram-negative microorganisms such as Pseudomonas aeruginosa (ATCC 27853), Escherichia coli (ATCC25922), and yeast Candida albicans were also evaluated for antimicrobial activity. The essential oil was assessed further against human liver (HEPG-2) and breast (MCF7) cell lines for anticancer properties. The findings suggest that, compared to the control, cardamom essential oil exhibits a significant zone of inhibition against all types of microbes except Pseudomonas aeruginosa. Additionally, for anti-cancer actions, the IC50 values were 42.3 µg/ml for MCF7 and 54 µg/ml for HEPG-2 cell lines, while IC90 results for MCF7 were 68.9 µg/ml and for HEPG-2 cell line were 80.7 µg/ml. The essential oil was developed in functional coating to preserve the postharvest mango fruit for 60 days at cold storage. The treated fruit showed reduced weight loss (10%), with a relative reduction of 78% compared to the control, chilling injury incidence (2.5%) at day 45, and rind pitting (3%) at day 30 compared to the control. This therapeutic plant may yield novel compounds for broad-spectrum antimicrobial and anticancer medicines and be transformed into economical and secure standardized herbal products.

Post-harvest cold shock treatment enhanced antioxidant capacity to reduce chilling injury and improves the shelf life of guava (Psidium guajava L.)

This study investigates the impact of storage temperature and cold shock treatment (CST) on the postharvest quality and shelf life of guava fruits. Guavas were stored at varying temperatures (4°C, 6°C, 8°C, and 10°C) for 25 days to evaluate the incidence of chilling injury (CI) and determine optimal storage conditions. Results indicated that the best storage temperature was 6°C, which effectively maintained fruit quality by inhibiting CI, controlling weight loss, and preserving soluble solid content and soluble sugars. Further analysis on the effect of CST on guavas showed that longer cold shock durations (6, 9, and 12 h) before storage at a constant 4°C improved the storage quality and shelf life significantly by decreasing the CI rates, reducing weight loss, maintaining firmness, and improving the fruit’s nutritional quality. Notably, a 12-h CST yielded the best outcomes, evidenced by the lowest malondialdehyde (MDA) content and the highest increases in proline and soluble protein content - biomarkers of enhanced cold tolerance and reduced CI. Additionally, CST was found to modulate the reactive oxygen species (ROS) metabolism, increasing the activity levels of key antioxidant enzymes such as superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX), alongside higher contents of ascorbic acid. The study identified a correlation between the length of cold shock and improved antioxidant capacity, crucial for extending guava’s shelf life and preserving quality during cold storage. These findings have significant implications for the postharvest management of guava, recommending 6°C storage and 12-h CST as effective strategies for extending shelf life and ensuring quality in cold storage settings.

Impact of Cold Storage Temperature and Shelf Life on Ripening Physiology, Quality Attributes, and Nutritional Value in Apricots-Implication of Cultivar.

This work aimed to investigate the storability potential of Orange Red and Orange Rubis apricots harvested at commercial maturity stage during cold storage (CS) at 1 or 5 °C for up to 28 days, followed by shelf life (SL) at 20 °C for 2 days. The variables evaluated included total soluble solids, titratable acidity, pH only at harvest, weight loss (WL), ethylene production rates, peel color, firmness, chilling injury incidence (CI), concentrations of total phenolics, flavonoids, carotenoids, total antioxidant capacity, b-carotene, b-cryptoxantine, and lutein. The main results showed that storage at 5 °C resulted in higher WL and CI symptoms than at 1 °C during both CS and SL, increased ethylene production during CS, whereas there was limited or no effect of CS temperatures on changes in firmness, color, and all antioxidants during CS. Firmness decreased abruptly soon after harvest in Orange Rubis, but progressively in the remaining samples of both cultivars during CS and SL. SL advanced fruit deterioration according to WL, CI, and softening. During SL, ethylene production increased in all samples. Orange Red exhibited higher ethylene rates during SL and antioxidant concentrations throughout CS and SL, by comparison. Conclusively, storage temperature at 1 °C retained WL, CI, and ethylene production, and both cultivars were marketable up to 21 days CS without SL or up to 14 days CS followed by SL, although Orange Rubis exhibited CI after 14 days, while Orange Red exhibited CI after 21 days of CS.

Postharvest trehalose application alleviates chilling injuring of cold storage guava through upregulation of SnRK1 and energy charge

Sucrose non-fermenting-1-related protein kinases-1 (SnRK1) plays a crucial role in response to energy homeostasis for plant survival during exposure to environmental stresses. Trehalose has been reported as chilling injury alleviating agent of postharvest guava (Psidium guajava cv. Kim Ju), but the mechanism related to energy homeostasis have not been elucidated. This research is focusing on the influence of exogenous trehalose on SnRK1 activation associated with energy homeostasis and chilling injury incidence of ‘Kim Ju’ guava fruit during low temperature storage. The fruits were treated with 0 and 200 mM of trehalose for 30 min and kept at 8 °C for 14 d. It was demonstrated that PgSnRK1 expression and SnRK1 activity increased after trehalose treatment, reaching maximum within 1–2 d. Trehalose treatment upregulated the expression of energy producing related genes including adenosine triphosphate synthase subunit β and adenosine diphosphate/adenosine triphosphate carrier and increased the enzyme activities of nicotinamide adenine dinucleotide dehydrogenase, succinate dehydrogenase and cytochrome c oxidase. These events were accompanied by higher energy charge and lower chilling injury throughout storage. The increase in SnRK1 activity by exogenous trehalose was closely associated with an increase in sucrose level during the first 2 d of storage. The SnRK1 activation was induced apparently by 50–200 mM exogenous sucrose within 3–12 h after treatment while exogenous trehalose treatment induced SnRK1 activation slightly and slowly within 2 d. Moreover, validamycin A combined with exogenous trehalose enhanced the cellular trehalose accumulation while sucrose level remained constant which lowered PgSnRK1 expression. Our results suggested that exogenous trehalose induces a transient rise in sucrose content at the early storage for providing the sugar signaling to SnRK1 activation which is required for maintaining energy homeostasis accompanied by retarding chilling injury.

Pre- or Post-Harvest Treatment with MeJA Improves Post-Harvest Storage of Lemon Fruit by Stimulating the Antioxidant System and Alleviating Chilling Injury.

Cold storage preserves lemon fruit quality; however, it can result in significant chilling injury (CI). The effects of pre- and post-harvest methyl jasmonate (MeJA) treatments at four concentrations (0, 0.1, 0.3, and 0.5 mM) on CI and sensory quality of lemons during 80 d of storage at 7-10 °C were investigated. Both pre- and post-harvest MeJA treatments reduced CI, weight loss (WL) and maintained higher firmness, total soluble solids (TSS), and total acidity (TA) than in the controls. Antioxidant enzyme activities decreased in the control fruit but increased in both pre- and post-harvest MeJA-treated fruit. In addition, phospholipase D (PLD) and lipoxygenase (LOX) activities and malondialdehyde (MDA) content were higher in the control than in the MeJA-treated fruit. Pre-harvest MeJA treatment generally preserved fruit better than post-harvest MeJA treatment, with the best results observed when MeJA was applied at 0.3 mM, which enhanced the antioxidant system of the lemon fruits, thus reducing the post-harvest incidence of chilling injury. These results have important implications for improved fruit quality post-harvest.

Melatonin alleviates chilling injury and maintains postharvest quality by enhancing antioxidant capacity and inhibiting cell wall degradation in cold-stored eggplant fruit

Melatonin improves the chilling tolerance and quality of postharvest fruit. In this study, we investigated the effect of melatonin on postharvest quality in cold-stored eggplant fruit for 30 d at 5 °C. Melatonin at 100 μmol L−1 was notably effective in decreasing chilling injury (CI) incidence, CI index, weight loss, and in delaying the decrease of lightness, thereby maintaining better postharvest quality of the fruit. Exogenous melatonin inhibited increases in hydrogen peroxide (H2O2), malondialdehyde (MDA), and relative electro-conductivity in the pericarp and pulp, while maintaining higher levels of superoxide dismutase (SOD), catalase (CAT), total polyamines, anthocyanins, and melatonin, as well as the expressions of SOD, CAT1/2, and other genes involved in polyamine biosynthesis (ADC, ODC), melatonin biosynthesis (TDC1, T5H, SNAT1, ASMT, COMT), anthocyanin biosynthesis (PAL, CHS1, CHI, F3H, F3′H, DFR, ANS, 3GT), and cold regulation (COR1, CBF, ZAT2/6/12), thereby conferring the higher chilling tolerance. Melatonin delayed fruit softening and senescence by inhibiting the activities and gene expressions of cell wall degradation enzymes (PME, PG, Cel) and expressions of senescence-associated genes (IAA17, SAG12, SEN4). Overall, these results indicate that melatonin alleviates chilling injury and maintains postharvest quality by enhancing antioxidant capacity and inhibiting cell wall degradation in cold-stored eggplant fruit, which provides a theoretical foundation for extending fruit shelf-life of eggplant during cold storage.

Evaluating the Efficacy of Gum Arabic-Zinc Oxide Nanoparticles Composite Coating on Shelf-Life Extension of Mandarins (cv. Kinnow).

Restricted postharvest application of synthetic fungicides in maintaining the quality of citrus fruits has led to a search for alternative postharvest treatments. This study evaluated the efficacy of gum arabic (GA) enriched with green synthesized zinc oxide nanoparticles (ZnO-NPs) in maintaining the postharvest quality of mandarin (cv. Kinnow). ZnO-NPs were synthesized using Bidens pilosa leaf extract and incorporated into GA (2% w/v) at 0, 0.25, 0.5, and 1% to form composite coatings: GA, GA + ZnO-NP 0.25%, GA + ZnO-NP 0.5% and GA + ZnO-NP 1%, respectively. Fruit were dipped for 3 min in the respective coatings, with untreated fruit used as control. Fruit were air-dried, packed in commercial cartons, and stored at 5 ± 1°C and 90 ± 5% relative humidity (RH) for 40 days and observed at 10 days intervals, plus 5 days at 20 ± 5°C and 65 ± 5% RH to determine the incidence of physiological disorders. GA + ZnO-NP showed promise as an alternative postharvest treatment for controlling postharvest physiological disorders associated with ‘Kinnow’ mandarin. For instance, GA + ZnO-NP 0.5% markedly minimized weight loss (9.2%), electrolyte leakage (43.8%) and chilling injury incidence (5.4%) compared to control (weight loss; 33.3%, electrolyte leakage; 90.3% and chilling injury incidence; 41.5%) at the end of the storage. GA + ZnO-NP 1% significantly alleviated rind pitting, with 13.2% incidence compared to 45.2% rind pitting incidence in the control fruit. This was due to significantly higher phytochemical and antioxidant capacity and reduced antioxidant enzyme degradation in coated fruit than in control. In conclusion, gum arabic coating enriched with ZnO-NPs at concentrations between 0.5 and 1% is recommended as a viable option to maintain the quality of ‘Kinnow’ mandarin fruit during cold storage.

Low‐dose prestorage 24‐epibrassinolide spray enhances postharvest chilling tolerance in zucchini squash ( Cucurbita pepo L.) by eliciting peroxidase and phenolic antioxidants

Brassinosteroids are polyhydroxy steroid hormones, tested to induce cold acclimation in whole plants and some harvested fruits. So far, no works have determined whether such strategy may improve the chilling tolerance of immaturely harvested Cucurbits, which are, among the most sensitive vegetables. Herein, we evaluated the efficacy of 24-epibrassinolide to reduce chilling injury in zucchini squash (Cucurbita pepo L.). Prestorage sprays at a dose 10–100 times lower than reported for postharvest use in other fruits (0.1 μM), markedly reduced chilling injury incidence (ca. 70%) and severity (30%–40%), decreased weight loss, and delayed yellowing. After long-term storage, epibrassinolide-sprayed zucchini maintained lower electrolyte leakage and lipid peroxidation. The treatment also increased fruit antioxidant defenses by inducing peroxidase and increasing antioxidant capacity, phenolic compounds, and peroxidase activity. This is the first report showing that low-dose prestorage 24-epibrassinolide priming enhances the cold tolerance of immaturely harvested Cucurbits, preventing postharvest chilling injury. Novelty impact statement This is the first study showing that brassinosteroid prestorage single spray at very low dose (0.1 μM) is sufficient to enhance the chilling tolerance of immaturely harvested Cucurbit vegetables. Epibrassinolide priming may be a feasible strategy to reduce chilling damage in highly sensitive zucchini squash.

Mitigation of chilling injury in sweet potato roots subjected to low-temperature conditioning

In many plant tissues, low-temperature conditioning (LTC) has been used to induce postharvest adaptive responses to overcome chilling injury (CI) consequences. This study aimed to investigate whether LTC is effective in reducing the incidence of chilling injury (CI) in sweet potato cultivars. Sweet potato roots BRS Cuia and BRS Rubissol were submitted to cold storage (6 °C or 13 °C) and LTC (10 °C for 7 d, followed by second storage at 6 °C). LTC increased the tolerance of sweet potato roots to CI via antioxidant system activation, mainly in cv. BRS Rubissol, which was markedly associated with higher content of both total soluble phenolics and proline, as well as increased activity of phenylalanine ammonium lyase. Moreover, no either external or internal injuries were observed in the LTC roots, maintaining the quality for processing, which indicates that the LTC is effective in mitigating chilling injury in Brazilian sweet potato cultiva

Application of intermittent warming to enhance postharvest quality and extend the shelf life of pomegranate fruit (Punica granatum)

Intermittent warming (IW) cycles slow down the physiology of fresh horticultural commodities, thereby extending their storage life. We investigated the effects of IW on physiological disorders, physicochemical, sensory parameters and the emission of volatile organic compounds (VOCs) of pomegranate (Punica granatum; cv. Wonderful) fruit during a 3-month cold storage period. Pomegranate fruit batches were subjected to IW cycles of 3d at 5°C, followed by 1 d at 20°C (IW 3d) and 6 d at 5°C, followed by 1 d at 20°C (IW 6d). During cold storage at 5°C, fruit samples were transferred to shelf-life conditions at 20°C for 4 d before analysis was performed monthly. Continuous fruit mass loss was observed across all treatments during storage but was highest (p < 0.05) for untreated samples at the end of this study. Fruit decay was minimized by 15% and 16% for IW 3d and IW 6d, respectively, compared to 42% for the control. In contrast, a higher incidence of chilling injury was observed in the treated fruits than in control. Therefore, IW 3 d at 5°C is recommended for decay reduction in pomegranate fruit (cv. Wonderful) and shelf-life extension for up to 3 months of storage.

Application of Calcium Chloride at Different Phenological Stages Alleviates Chilling Injury and Delays Climacteric Ripening in Peach Fruit during Low-Temperature Storage

ABSTRACT Owing to the high degree of perishability of the fruit, the peach industry faces serious challenges tackling physiological disorders, microbial/chemical decay, and the suboptimal quality of the fruit during and following cold storage. The present study was aimed to investigate the effects of spray applications of calcium chloride (CaCl2) at various physiological stages of fruit growth and development, on ripening, flesh softening, chilling injury (CI) and nutritional quality of peach fruit cv “Flordaking” during low-temperature storage. The aqueous solutions of CaCl2 [0, 1, 2, and 3% (w/v)] were sprayed on peach trees during cell division, pit hardening and cell expansion stages in 2011 and 2012. At commercial harvest, the fruit were hand-picked and were subjected to cold storage at 1 ± 1°C (RH: 90 ± 5%) for 6 weeks. The data on CI index and other quality characteristics of the fruit were recorded at harvest and then weekly for up to 6 weeks. The results showed that the pre-harvest spray application of CaCl2 substantially reduced the incidence of chilling injury (CI) and delayed climacteric ripening seemingly by lowering the rates of ethylene production and fruit softening during storage as compared to control, regardless the doses of CaCl2 and its application time, however higher doses of calcium chloride proved to be toxic causing blemishes on the surface of “Flordaking” peaches. In conclusion, pre-harvest spray application of CaCl2 @ 1% may be a successful production management tool to maintain the quality and to extend storability of peach fruit during cold storage.

Regulatory influences of methyl jasmonate and calcium chloride on chilling injury of banana fruit during cold storage and ripening.

Fruit quality is preserved through cold storage, but climacteric fruits are prone to chilling injury (CI) which limits their shelf life and marketability. Two postharvest treatments, 1 mM methyl jasmonate (MeJA) and 4% (wt/vol) calcium chloride (Ca2+), were separately used to investigate their influences on chilling injury (CI) incidence and fruit quality in unpacked banana cultivar “Grand Nain” during cold storage and subsequent ripening. Banana fruits were dipped for 2 min in aqueous emulsions containing 1% Tween‐80—used here as a surfactant with untreated fruits being used as control. Fruits were stored at 10 ± 2 or optimal 14 ± 2°C temperature and relative humidity 85%–90% for a 20‐day cold storage period and then removed from cold storage at 5, 10, 15, and 20 days followed by ripening at 22 ± 2°C. Treatments with MeJA or Ca2+ significantly reduced CI in banana fruit during cold storage and subsequent ripening temperature. Untreated controls exhibited increased CI, weight loss, and decreased hue angle, as well as firmness. In contrast, the aforementioned changes were considerably delayed after treatments with MeJA or Ca2+. Application of MeJA or Ca2+ also increased total phenolic compound contents and maintenance of total antioxidant activity throughout cold storage and during ripening periods as compared to that of the control. These findings indicate that coating bananas with 1 mM MeJA or 4% (wt/vol) Ca2+ can improve the postharvest quality and shelf life of fruits, and it can ameliorate chilling injury during cold storage and at ripening temperature.

Intermittent warming as an efficient postharvest treatment affects the enzymatic and non-enzymatic responses of pomegranate during cold storage

Limited shelf life of pomegranate makes its cold storage necessary. On the other hand, it encounters chilling injury (CI) incidence at temperatures below 5 oC. Intermittent warming (IW), known as one or more warming periods during cold storage, is a beneficial postharvest treatment for keeping fruit quality. Pomegranate ‘Rabab-e-Neyriz’ fruit were stored at 2 ± 0.5 °C (chilling temperature) and 90 ± 5% relative humidity (RH) for 70 days. IW was performed as one warming period by transferring the fruit to a warm room (1 day at 20 °C with 70% RH). The experimental design was factorial based on a complete randomized design. Experimental factors included 4 temporal points of interruption in storage, i.e., 15th, 25th, 35th or 45th days of storage; 2 levels of warming regime for each interruption date, i.e., warming and control; and 2 levels of sampling time, i.e., immediately after treatment or postponed until the end of the storage period. Treated fruit were compared to controls twice, immediately after treatment and at the end of the storage period. Warming on the 15th day of storage led to higher enzymatic antioxidant activity and phenolic content coincided with lower polyphenol oxidase (PPO) activity in the peel and, as a result, lower chilling injury (CI) damage to the treated fruit compared to control. It was concluded that a successful and commercially applicable method for postharvest cold storage of pomegranate could be the only one warming period prior to the incidence of irreversible damage.

Melatonin ameliorates chilling injury in green bell peppers during storage by regulating membrane lipid metabolism and antioxidant capacity

Abstract Melatonin is a kind of indoleamine that plays an important role against abiotic stress. In the current study, we investigated the effect of exogenous melatonin (100 μM) on bell pepper during storage at 4 °C for 20 d and afterward shelf at 20 °C for 3 d. Melatonin treatment reduced cell structure damage and lightened the increase in chilling injury incidence, membrane permeability, and malonaldehyde (MDA) content under cold stress. The membrane lipid content and the ratio of unsaturated to saturated fatty acids increased by reducing the enzymatic activity and transcripts of phospholipase D (PLD) and lipoxygenase (LOX). Besides, melatonin application also inhibited the transcription of CaNAC1, which is the direct targeted regulator of the CaPLD gene. In addition, peppers treated with melatonin had a higher proline content than untreated peppers. Moreover, melatonin triggered the antioxidation protection system in peppers to resist oxidative damage by up-regulating the transcription level of the CaSOD, CaPOD, CaCAT, and CaAPX genes. Our results show that melatonin treatment may be a reliable method to relieve chilling injury in bell pepper fruit via the alleviation of cold-induced membrane lipid peroxidation and activating an antioxidant defense system.

Improving postharvest storage of fresh red-fleshed pitaya (Hylocereus polyrhizus sp.) fruit by pre-harvest application of CPPU

The appearance, flavor, and taste are important criteria of fruit quality, which is affected by environmental conditions, orchard management, and postharvest storage. The current study was conducted to investigate the influence of the pre-harvest application of forchlorfenuron (CPPU) on the red-fleshed cv. ‘Fu Kwai Hong’ pitaya (Hylocereus polyrhizus sp.) fruit during storage at 5 °C. On the flowering day, 100 mg L−1 CPPU was sprayed on the bracts and water was used as the control. The significantly higher bract thickness (1.49 mm and 1.67 mm), shorter fruit length (88.6 mm and 99.4 mm), lower fruit shape index (0.91 and 0.95), and less cracking ratio (0% and 2.17%) were recorded on CPPU treated fruit in both winter and summer seasons, respectively. Moreover, CPPU resulted in more chlorophyll a, chlorophyll b, and total chlorophyll content in the bracts than in the control, which caused fresh-green color of the bracts when CPPU treated fruit was harvested compared to the control, and was significantly less degree of bract browning than the control fruit during storage. Additionally, CPPU treated fruit exhibited later incidence of chilling injury than the control fruit during 5 °C storage. On the other hand, CPPU treated fruit had more weight loss and a slight increase of respiration rate compared to the control during storage at 5 °C.

Influence of storage period and shelf-life on the incidence of chilling injury and microbial load in "Angeleno" and "Larry Ann" plums

Refrigeration is the most widely used post-harvest technology for increasing commercial life (shelf-life) of plums after harvest. Nevertheless, low-temperature conservation is limited by chilling injury (CI), leading to rejection by consumers. The objective of the present work was to characterize biotic and non-biotic chilling injures that lead to quality loss in plums during post-harvest storage. Larry Ann and Angeleno plums were stored at 1.0±0.5°C and 90.0±2.0% RH for 4 and 8 weeks and after this period the plums were stored either 3 or 6 days at 20ºC for evaluating changes in their shelf-life. Pulp firmness, post-harvest losses, presence of chilling injuries and the count of mesophilic microorganisms, molds and yeasts were determined after harvest and after storage plus shelf-life. In general, a drastic decrease in the growth of bacteria, mold and yeast during post-harvest storage at 1ºC was observed, following an increased microbial growth during shelf-life storage. Sensitivity to low temperature was cultivar-dependent. Larry Ann plums showed higher pulp firmness reduction and lower impact of CI than Angeleno, with an increased microbial spoilage. Plums that presented cold-damaged or physiologically compromised tissues suffered from faster decomposition and provided a better substrate for microbial growth than non-damaged plums.

Effect of Hot Water Exposure Duration, Storage and Hot Water Temperature on Chilling Injury, Incidence and Quality of Keitt Mango (Mangifera indica L.)

Low temperature storage is the most effective method of extending postharvest life and maintain fruit quality because it delays physiological processes such as ethylene production and senescence. Unfortunately, fruit such as mangoes are sensitive to low temperature storage and may be detrimental due to chilling injury, which reduces fruit quality. Effects of storage temperature, hot water at various temperatures and durations on alleviation of mango chilling injury and quality were evaluated on Keitt mango for the growing season in Botswana. The treatments were fruits dipped in distilled water at room temperature (25±2ºC- control), dipped in hot water at 50 and 55ºC for duration of 3, 5 and 10 minutes and storage temperatures at 4, 7, 10, 13 and 25±2ºC, plus 95% RH. The results showed that as storage temperature at below 13ºC, chilling injury incidence and severity significantly (P ≤ 0.0001) increased. Atwater temperature from 25ºC to 50 and 55ºC and duration in which mango fruit was held in hot water, increased from 3 to 5 and 10 minutes, chilling injury incidence and severity significantly (P ≤ 0.0001) decreased.

Effect of 24-Epibrassinolide Treatment on Quality of Baby Ginger during Low Temperature Storage

In order to extend the storage life,the effects of exogenous 24-epibrassinolide(EBR)treatment on quality of baby ginger stored at low temperature were investigated. The baby ginger were treated with 5,10 μmol/L EBR for 30 min respectively,and that treated with distilled water as controls,then stored at 4 ℃ for 25 days. Changes in chilling injury incidence,color and the contents of vitamin C,total flavonoids,gingerol,soluble sugar and soluble protein were analyzed regularly. Results showed that EBR treatment significantly reduced chilling injury incidence(P<0.05),maintained good color of baby ginger during low temperature storage,and the high levels of vitamin C,gingerol,total flavonoids,soluble sugar and soluble protein as well. At the end of storage,the chilling injury incidence in 10 μmol/L EBR-treated group was 38.4% of control group(P<0.05). The contents of gingerol,total flavonoids and soluble protein were 27.6%,25.0% and 40.8% higher in 10 μmol/L EBR-treated group than that in control(P<0.05),and the levels of vitamin C and soluble protein were 1.71 and 2.50 times of control group(P<0.05). These results indicated that EBR improves the chilling tolerance and quality of baby ginger during low temperature storage,which has potential for application in postharvest industry.

Nitric oxide fumigation alleviates chilling injury and regulates fruit quality in sweet orange stored at different cold temperatures

The cold storage of sweet oranges below 7 °C causes chilling injury and adversely affects fruit quality. Midknight Valencia and Lane Late sweet oranges were fumigated for 2 hours with different concentrations (5, 10 or 20 µL L-1) of nitric oxide (NO) and stored at (4 or 7 °C) to investigate the effect on chilling injury incidence (CI) and fruit quality after 90 days storage followed by 10 days simulated shelf conditions. Untreated fruit served as a control. The experimental design completely randomised with two factors including NO fumigation treatments and storage temperatures. All NO fumigation treatments (5, 10 or 20 µL L-1) significantly reduced the CI irrespective of storage temperature as compared to the control in both the cultivars. Fruit were fumigated with different concentration of NO gas in a sealed container for 2 h and then kept at 4°C and 7°C. Fruit quality variables such as fruit firmness, SSC (%), TA (%), SSC/TA, sugars, vitamin C and total antioxidants were determined. All the NO treatments significantly reduced per cent weight loss as compared to control in Lane Late. Mean weight losses were higher (8.3 % and 5.5 %) when fruit were stored at 7 °C as compared to those stored at 4 °C (4.8 % and 3.5 %) in Midknight Valencia and Lane Late respectively. All the NO fumigation treatments significantly reduced the mean concentrations of glucose, fructose, sucrose and total sugars in the juice of Midknight Valencia only. All NO fumigation treatments significantly reduced mean concentration vitamin C in the fruit juice of Lane Late as compared to the control. Meanwhile, in Midknight Valencia, NO (10 or 20 µL L-1) fumigated fruit showed a significant reduction in the mean concentration of vitamin C as compared to NO (5 µL L-1) fumigation and control. The juice of Midknight Valencia had higher mean total antioxidants when fumigated with NO (5 µL L-1) as compared to the control, but not in Lane Late. In conclusion, all the NO fumigation (10 µL L-1) treatment was most effective in reducing CIin both cultivars irrespective of the cold storage temperature. NO fumigation treatments did not affect SCC/TA ratio but reduced all the individual and total sugars as well as vitamin C in the fruit stored for 90 days followed by 10 days simulated shelf conditions.