Modified ethanol atmosphere to control decay of table grapes during storage

The efficacy of three methods of applying ethanol to prevent storage decay was tested on two cultivars of table grapes, ‘Superior’ and ‘Thompson Seedless’. Ethanol was applied by: (1) dipping grapes in 50% ethanol for 10 s followed by air drying before packaging; (2) placing a container with a wick and 4 or 8 ml ethanol/kg grapes inside the package; (3) applying 4 or 8 ml ethanol/kg grapes to paper and placing this paper above the grapes in the package. The grapes were stored for 6 or 8 weeks at 0 °C and assessed after an additional 3 days at 20 °C. All methods of application controlled decay as well as or better than a SO₂-releasing pad. The ethanol impregnated paper caused high levels of berry browning, perhaps because of high levels of acetaldehyde inside the package. However, the taste of the berries was not impaired by any of the ethanol applications. The taste of ‘Thompson Seedless’ grapes stored for 8 weeks in modified atmosphere storage was affected by CO₂ levels above 7%. Some methods of applying ethanol used here show promise as alternatives to SO₂ to prevent decay of grapes during storage while maintaining fruit quality.     

Modified atmosphere packaging and ethanol vapor to control decay of ‘Red Globe’ table grapes during storage

The aim of this study was to determine the efficacy of several alternative postharvest treatments to sulfur dioxide (SO₂) in maintaining quality and reducing fungal decay during cold storage of ‘Red Globe’ table grapes. Grapes were packaged in perforated polyethylene (PPE) or modified atmosphere packaging (MAP) bags (ZOEpac or Antimicrobial) with or without different grades of ethanol vapor-generating sachets (Antimold^®30, Antimold^®60 or Antimold^®80) or a SO₂-generating pad, and the grapes were kept at 0 °C and 90-95% relative humidity for 4 months. Packaging of grapes with a SO₂ pad in PPE or ZOEpac bags provided better control of fungal decay and stem browning than PPE or ZOEpac bags alone, PPE or ZOEpac bags with Antimold sachets or Antimicrobial bags alone. The PPE bag containing the Antimold^®80 sachet was as effective as the SO₂ treatments in reducing the incidence of fungal decay in naturally infected and artificially inoculated grapes for 1 month. Ethanol vapor released by the Antimold sachets enhanced berry color, but caused stem browning depending on ethanol vapor concentrations in the headspace of the bags. The ZOEpac-210 bags alone resulted in significantly lower weight loss and incidence of stem browning, compared to other treatments; however, they did not reduce fungal decay or develop an appreciable level of modified atmosphere.     

Effectiveness of a short hyperbaric treatment to control postharvest decay of sweet cherries and table grapes

The effectiveness of short hyperbaric treatments to control postharvest decay of sweet cherries (Prunus avium L., cv Ferrovia) and table grapes (Vitis vinifera L., cv Italia) was investigated. Sweet cherries and table grape berries were exposed to the pressure of 1140 mmHg (1.5 atm) for 4 and 24 h, respectively, in 64 L gas-proof tanks. Fruit kept at ambient pressure (near 760 mmHg, 1.0 atm) served as a control. Postharvest rots of sweet cherries arose from naturally occurring infections, whereas table grape berries were artificially wounded, exposed to the hyperbaric treatment, then the wounds inoculated with 20 μL of a Botrytis cinerea conidial suspension (5 × 10⁴ spores mL⁻¹). Sweet cherries were stored at 0 ± 1 °C for 14 d, followed by 7 d at 20 ± 1 °C. Table grapes berries were kept at 20 ± 1 °C for 3 d. On sweet cherries, hyperbaric treatment reduced the incidence of brown rot, grey mould, and blue mould, with respect to the control. Similarly, on treated table grapes a significant reduction of lesion diameter and percentage of B. cinerea infected berries was observed. Induced resistance was likely to be responsible for the observed decay reduction. To our knowledge, this is the first report on the effectiveness of short hyperbaric treatments in controlling postharvest decay of sweet cherries and table grapes.     

Preharvest applications of growth regulators and their effect on postharvest quality of table grapes during cold storage

Over 54,600 ha of table grapes (Vitis vinifera), mainly cvs. ‘Thompson Seedless’, ‘Flame Seedless’ and ‘Redglobe’, are planted in Chile. Almost the entire production is exported to the USA, Europe, Asia, or one of several Latin American countries, which typically requires 15–40 d of maritime transportation. During this period, several physical, physiological, and pathological factors cause table grape deterioration. Because berry size is the main quality factor in international markets, farmers often overuse the growth regulators, gibberellic acid (GA₃) and forchlorfenuron (CPPU), in an effort to increase berry size. We examined the effect of preharvest growth regulators on seedless (‘Thompson Seedless’, and ‘Ruby Seedless’) and seeded (‘Redglobe’) table grape cultivars during cold (0 °C) storage plus a shelf life period of 3 d at 20 °C. The overuse of GA₃, eight instead of two GA₃ applications on Thompson Seedless, and the use of one GA₃ application on Redglobe and ‘Ruby Seedless’, increased berry pedicel thickness and lowered cuticle content but induced shatter and predisposed grapes to gray mold caused by Botrytis cinerea. In contrast, CPPU increased berry pedicel thickness and cuticle content but did not increase shatter or gray mold incidence. Clusters that were subjected to overuse of combined GA₃ and CPPU were highly sensitive to shatter, had the thickest pedicel, and developed a high gray mold incidence during cold storage. Hairline, a fine cracking developed during cold storage, was induced on ‘Thompson Seedless’ and ‘Ruby Seedless’ by growth regulators, but no hairline occurred on ‘Redglobe’ table grapes. Therefore, berry quality during cold storage is greatly influenced by growth regulator management in the vineyard.     

Estimates of genotypic and yearly variations on fruit quality and functional traits for tetraploid table grape breeding

We estimated genetic and environmental variance components for fruit quality traits (cluster weight, berry weight, soluble solids content, total sugar content, sugar composition, free acid content, total amino acid content, amino acid composition), and a functional trait (gamma-aminobutyric acid (GABA) content) of three commercial tetraploid table grape cultivars (Kyoho, Pione, Suiho) grown in Japan over three successive years. ANOVA showed that the effect of genotype was significant (P < 0.05) for all traits except soluble solids content and total sugar content. The effect of the year was significant for all traits except amino acid composition (γ ratio) and GABA content. The variance of genotype (σ _g ²) was highest for γ ratio (63.6%), high in sugar composition (α ratio, 60.3%) and GABA content (58.8%), and negligible for soluble solids content (0.0%) and total sugar content (0.0%). The variance of among years (σ _y ²) was very high in soluble solids content (82.8%), high in total sugar content (60.2%) and negligibly small in γ ratio (8.7%) and GABA content (6.4%). Some effects of genotype × year interaction, among vines within genotypes, and vine × year interaction were statistically significant, but these components were negligibly small. Except for soluble solids content and total sugar content, significant varietal differences in the traits were recorded. Variance estimates for each trait provides useful information for optimal yearly repetition to effectively discriminate genetic differences in fruit quality and functional traits for improving future tetraploid table grape breeding programs.     

Effectiveness of postharvest treatment with chitosan and other resistance inducers in the control of storage decay of strawberry

This study compared the effectiveness of practical grade chitosan when used in solution with acetic, glutamic, formic and hydrochloric acids, and a water-soluble commercial chitosan formulation, in controlling postharvest diseases of strawberry. The commercial chitosan formulation and other resistance inducers based on benzothiadiazole, oligosaccharides, soybean lecithin, calcium and organic acids, and Abies sibirica and Urtica dioica extracts were also tested. The commercial chitosan formulation was as effective as the practical grade chitosan solutions in the control of gray mold and Rhizopus rot of strawberries immersed in these solutions and kept for 4 days at 20 ± 1 °C. Moreover, the treatment with commercial and experimental resistance inducers reduced gray mold, Rhizopus rot and blue mold of strawberries stored 7 days at 0 ± 1 °C and then exposed to 3 days shelf-life. The highest disease reduction was obtained with the commercial chitosan formulation, followed by benzothiadiazole, calcium and organic acids. The compounds that provided the best results in postharvest applications to control storage decay of strawberries, should be tested in further trials through preharvest treatments, applied at flowering and a few days before harvest.     

1-MCP处理对黄瓜冷藏期间保鲜效果的影响

以“叶三”黄瓜果实为材料,采用10 ppm1-MCP处理24 h后,与对照(CK)同时转入0℃低温冷藏,并对低温贮藏过程中的黄瓜感官品质、组织相对电导率、可滴定酸(TA)、Vc含量和失重率的变化进行了研究,结果表明,1-MCP处理可抑制低温贮藏中黄瓜相对电导率的上升,减缓黄瓜果实冷害症状的发展,同时延缓Vc和可滴定酸的下降速率,维持黄瓜较好品质。     

Efficacy of ethanolic extract of propolis in maintaining postharvest quality of dragon fruit during storage

Significant (P ≤ 0.05) differences were observed in dragon fruit quality when treated with different concentrations of ethanolic extract of propolis (EEP) (0.25, 0.50, 0.75 and 1.0%) and stored at 20 ± 2 °C and 80 ± 5% relative humidity (RH) for 20 days. Fruit treated with 0.50% EEP showed the most promising results, while fruit treated with 0.75 and 1.0% EEP showed some phytotoxic effects even after 8 days of storage. The results of gas exchange analysis also proved the efficacy of 0.50% EEP concentration. Thus, it can be concluded from the present investigation that EEP at 0.50% concentration could be used to extend the storage life of dragon fruit without any negative effects on the quality.     

Ethanol vapor and saprophytic yeast treatments reduce decay and maintain quality of intact and fresh-cut sweet cherries

The objective of this study was to evaluate the use of an ethanol vapor release pad and a saprophytic yeast Cryptococcus infirmo-miniatum (CIM) to reduce decay and maintain postharvest quality of intact or fresh-cut sweet cherries (Prunus avium) cv. Lapins and Bing. Intact or fresh-cut fruit were packed in perforated clamshells (capacity 454 g) and stored at 1, 10 or 20 °C for up to 21, 14 and 8 d, respectively. For ethanol treatment, a pad made with silica gel powder containing 10 g ethanol and covered with perforated film, which allows ethanol vapor to diffuse gradually, was attached to the upper lid of the clamshells. Ethanol treatment caused accumulation of ethanol in the packaging headspace, about 10 μL L⁻¹ with little change within 14 d at 1 °C, 23 μL L⁻¹ at d 1 and decreased to 15 μL L⁻¹ at d 10 at 10 °C, and 26 μL L⁻¹ at d 1 and decreased to 13 μL L⁻¹ at d 3 at 20 °C. Ethanol content in fruit was less than 9 mg kg⁻¹ in all the control fruit, and increased to 16, 34 and 43 mg kg⁻¹ in ethanol-treated fruit at 1, 10 and 20 °C, respectively. Nonetheless, a sensory taste panel did not perceive any flavor difference from the ethanol treatment. The ethanol treatment retarded softening, darkening, and acid decrease in fruit as well as discoloration of the stems, and extended shelf-life of intact cherries. Ethanol reduced brown rot (Monilinia fructicola) in fresh-cut cherries stored at 20 °C, but not at 1 and 10 °C. A pre-packaging dip in CIM completely controlled brown rot in inoculated fresh-cut cherries stored at 1 °C, and in naturally infected cherries at 20 °C.     

Effects of alginate edible coating on preserving fruit quality in four plum cultivars during postharvest storage

Four plum (Prunus salicina Lindl.) cultivars (“Blackamber”, “Larry Ann”, “Golden Globe” and “Songold”), were treated with 1 or 3% alginate as an edible coating before storage. Analytical determinations were made after 7, 14, 21, 28 and 35 days at 2 °C and after a 3 day period at 20 °C (shelf-life). Both treatments were effective in inhibiting ethylene production for all cultivars, especially when 3% alginate was used. The changes in fruit quality parameters related to plum postharvest ripening, such as weight and acidity losses, softening and colour changes, were significantly delayed by the use of both edible coatings. The delay of the ripening process was also related to lower anthocyanin and carotenoid accumulation. Overall results suggest that these treatments could increase the plum storage period with optimum quality, 2 weeks for “Larry Ann” and “Songold” and 3 weeks for “Blackamber” and “Golden Globe” more than controls.     

Interaction of temperature control deficiencies and atmosphere conditions during blueberry storage on quality outcomes

Southern hemisphere blueberry producers often export their products through extended supply chains to Northern hemisphere consumers. During extended storage, small variations in temperature or atmosphere concentrations may generate significant differences in final product quality. In addition, relatively short delays in establishing cool storage temperatures may contribute to quality loss. In these experiments a full factorial analysis was done of the effects of three cooling delays (0, 12 or 24 h at 10 °C), three atmosphere concentrations (air, 10% CO₂ + 2.5% O₂ and 10% CO₂ + 20% O₂) and two storage temperatures (0 °C and 4 °C) which were assessed for their impact on final quality, measured as weight loss, firmness and rot incidence. Two blueberry cultivars were studied: ‘Brigitta’, a highbush cultivar, and ‘Maru’, a rabbiteye. Delays in cooling had a small effect on final product weight, whereas variation in storage temperature and atmosphere during simulated transport influenced both firmness and rot incidence. Atmospheres with 10% CO₂ reduced decay incidence, particularly at low oxygen concentration (2.5% O₂), although the latter conditions tended to soften fruit. In order to achieve optimal postharvest storage for blueberries, minimising temperature variability in the supply chain is important, as is finding the potentially cultivar-specific optimal combination of high CO₂ and low O₂ concentration that results in simultaneously minimising rot incidence and induced softening.     

Calcium chloride extends the keeping quality of fig fruit (Ficus carica L.) during storage and shelf-life

The effects of postharvest application of fruit hardening chemical agents on fig (Ficus carica L. cv. Poona) fruit were compared with untreated figs during storage. The impact of calcium chloride (4%) was notable in terms of retention of fruit color, texture and increased accumulation of ascorbic acid, compared to untreated control figs. Pretreatment with calcium chloride (4%) was found to be most effective in checking the growth of both mesophilic aerobic bacteria and yeast and molds at low temperature (1 ± 0.5 °C; 95–98% RH) storage and it further delayed ripening and senescence of figs and was beneficial in prolonging the postharvest life twofold. Treated figs without microbial spoilage could be used for short term storage, transportation, distribution and marketing for long distance domestic markets in India.     

Effectiveness of submicron chitosan dispersions in controlling anthracnose and maintaining quality of dragon fruit

Conventional chitosan (CC) and submicron chitosan dispersions (SCD) were evaluated for the control of postharvest anthracnose and maintenance of quality of dragon fruit during storage at 10 ± 2 °C and 80 ± 5% RH for 28 days. All the chitosan treatments significantly reduced anthracnose symptoms, resulting in a reduction of disease development and thereby maintained the quality of fresh fruit for extended periods. SCD at 1.0% with 600 nm droplet size gave the best result in that it delayed the onset of disease and maintained the quality of dragon fruit for up to 28 days of storage. It can be concluded from the present investigation that SCD have potential to be used as an antifungal agent to control postharvest anthracnose and maintain quality of dragon fruit during storage.     

Combination of hot water,Bacillus amyloliquefaciens HF-01 and sodium bicarbonate treatments to control postharvest decay of mandarin fruit

An antagonistic isolate Bacillus amyloliquefaciens HF-01, sodium bicarbonate (SBC) and hot water treatment (HW) were investigated individually and in combination against green and blue mold and sour rot caused by Penicillium digitatum, P. italicum and Geotrichum citri-aurantii respectively, in mandarin fruit. Populations of antagonists were stable in the presence of 1% or 2% SBC treatment, and spore germination of pathogens in potato dextrose broth was greatly controlled by the hot water treatment of 45 °C for 2 min. Individual application of sodium bicarbonate at low rates and hot water treatment, although reducing disease incidence after 8 weeks or 4 weeks of storage at 6 °C or 25 °C respectively, was not as effective as the fungicide treatment. The treatment comprising B. amyloliquefaciens combined with 2% SBC or/and HW (45 °C for 2 min) was as effective as the fungicide treatment and reduced decay to less than 80% compared to the control. B. amyloliquefaciens HF-01 alone or in combination with 2% SBC or/and HW significantly reduced postharvest decay without impairing fruit quality after storage at 25 °C for 4 weeks or at 6 °C for 8 weeks. These results suggest that the combination of B. amyloliquefaciens HF-01, SBC and HW could be a promising method for the control of postharvest decay on citrus while maintaining fruit quality after harvest.     

Effect of postharvest biofumigation on fungal decay,sensory quality,and antioxidant levels of blueberry fruit

Postharvest decay, caused by various fungal pathogens, is an important concern in commercial blueberry production, but current options for managing postharvest diseases are limited for this crop. Four plant essential oils (cinnamon oil, linalool, p-cymene, and peppermint leaf oil) and the plant oil-derived biofungicides Sporan (rosemary and wintergreen oils) and Sporatec (rosemary, clove, and thyme oils) were evaluated as postharvest biofumigants to manage fungal decay under refrigerated holding conditions. Hand-harvested Tifblue rabbiteye blueberry fruit were inoculated at the stem end with conidial suspensions of Alternaria alternata, Botrytis cinerea, Colletotrichum acutatum, or sterile deionized water (check inoculation) and subjected to biofumigation treatments under refrigeration (7 °C) for 1 wk. Sporatec volatiles reduced disease incidence significantly (P < 0.05) in most cases, whereas other treatments had no consistent effect on postharvest decay. Sensory analysis of uninoculated, biofumigated berries was performed utilizing a trained sensory panel, and biofumigation was found to have significant negative impacts on several sensory attributes such as sourness, astringency, juiciness, bitterness, and blueberry-like flavor. Biofumigated fruit were also analyzed for antioxidant capacity and individual anthocyanins, and no consistent effects on these antioxidant-related variables were found in treated berries. Because of limited efficacy in reducing postharvest decay, negative impacts on sensory qualities, and failure to increase antioxidant levels, the potential for postharvest biofumigation of blueberries under refrigerated holding conditions appears limited.     

Timing and sequence of postharvest fungicide and biocontrol agent applications for control of pear decay

Postharvest decay of pear fruit often originates at small wounds that occur during harvest and handling. Experiments were conducted to characterize the effect of timing of application of postharvest decay control materials, and to evaluate sequential postharvest applications of fungicides or fungicides and biocontrol agents. Fungicides and biocontrol agents were increasingly less effective when the period between harvest and application was prolonged. Thiabendazole (TBZ) applied to fruit without artificial wounding or inoculation effectively reduced decay when applied within 3 weeks or 6 weeks in 2 years of study. TBZ, fludioxonil, and pyrimethanil were effective in controlling decay at artificial wounds inoculated with Penicillium expansum up to 14 d after inoculation. Application of TBZ at harvest followed 3 weeks later by application of fludioxonil was superior to application of TBZ at harvest alone. Three yeast and one bacterial biocontrol agents reduced decay at pear wounds inoculated with P. expansum up to 14 d after inoculation with P. expansum, but were ineffective when applied at 28 d after inoculation. Of possible sequential arrangements of fungicide and biocontrol treatments, application of the most effective material promptly after harvest generally resulted in the highest level of decay control.     

Girdling and gibberellic acid effects on yield and quality of a seedless red table grape for saving irrigation water supply

Table grapes need of substantial water supply for achieving commercial requirements. Viticulture practices such as girdling (G) and gibberellic acid (GA) application, as well as water supply, can improve table grape quality. The study, which was conducted in two consecutive seasons (2010–2011), aimed to assess the counterbalance effect of these viticulture practices on yield and quality parameters and flavonoids composition in case of a significant and unusual irrigation water reduction (40%) applied to a table grape variety. The data from the two-way ANOVA and PCA analyses indicated that viticulture practices were clearly related to anthocyanins and flavonols variations whereas water management appeared mainly involved in the yield parameters variability. Specifically, the reduced water supply (RWS) decreased the grape yield (−20%) with respect to full water supply (FWS); by contrast GA, G, and G × GA treatments determined an increment of grape production ranging from 10 to 23%, independently from irrigation strategy. Moreover, G, in particular applied to RWS grapes, was able to improve the total soluble solids over titrable acidity (TSS/TA), a ratio strictly related to the quality perception by the consumer. Total anthocyanins were found positively linked to FWS whereas flavanols content was indifferent to water management. Instead viticulture practices seemed to have a greater impact on anthocyanin composition, considering that in RWS grapes under GA condition, higher contents of malvidin and peonidin (mainly responsible for the color stability of the skins) were revealed. Furtheremore, catechins and rutin appeared significantly enhanced by G and G × GA, and GA, respectively. From gathered findings, it can be concluded that suitable viticulture practices can allow a sensible reduction of water supply during table grape growth cycle without detrimental effects on yield and quality.     

Respiration and quality responses of sweet cherry to different atmospheres during cold storage and shipping

Most sweet cherries produced in the US Pacific Northwest and shipped to distant markets are often in storage and transit for over 3 weeks. The objectives of this research were to study the effects of sweet cherry storage O₂ and CO₂ concentrations on the respiratory physiology and the efficacy of modified atmosphere packaging (MAP) on extending shelf life. Oxygen depletion and CO₂ formation by ‘Bing’ and ‘Sweetheart’ cherry fruit were measured. While respiration rate was inhibited linearly by reduced O₂ concentration from 21% to 3–4% at 20 °C, it was affected very little from 21% to ∼10% but declined logarithmically from ∼10% to ∼1% at 0 °C. Estimated fermentation induction points determined by a specific increased respiratory quotient were less than 1% and 3–4% O₂ for both cultivars at 0 and 20 °C, respectively. ‘Bing’ and ‘Sweetheart’ cherry fruits were packaged (∼8 kg/box) in 5 different commercial MAP box liners and a standard macro-perforated polyethylene box liner (as control) and stored at 0 °C for 6 weeks. MAP liners that equilibrated with atmospheres of 1.8–8.0% O₂ + 7.3–10.3% CO₂ reduced fruit respiration rate, maintained higher titratable acidity (TA) and flavor compared to control fruit after 4 and 6 weeks of cold storage. In contrast, MAP liners that equilibrated with atmospheres of 9.9–14.4% O₂ + 5.7–12.9% CO₂ had little effect on inhibiting respiration rate and TA loss and maintaining flavor during cold storage. All five MAP liners maintained higher fruit firmness (FF) compared to control fruit after 6 weeks of cold storage. In conclusion, storage atmospheres of 1.8–14.4% O₂ + 5.7–12.9% CO₂ generated by commercial MAP, maintained higher FF, but only the MAP with lower O₂ permeability (i.e., equilibrated at 1.8–8.0% O₂) maintained flavor of sweet cherries compared to the standard macro-perforated liners at 0 °C. MAP with appropriate gas permeability (i.e., equilibrated at 5–8% O₂ at 0 °C) may be suitable for commercial application to maintain flavor without damaging the fruit through fermentation, even if temperature fluctuations, common in commercial storage and shipping, do occur.     

Improving quality of greenhouse tomato (Solanum lycopersicum L.) by pre- and postharvest applications of hexanal-containing formulations

From harvest to consumption, tomato (Solanum lycopersicum L.) fruit are exposed to several exogenous factors that enhance product deterioration. Phospholipase D is a key enzyme involved in membrane deterioration that occurs during fruit ripening and senescence. Hexanal, an inhibitor of phospholipase D has been successfully used for pre- and postharvest treatment of fruit, vegetables and flowers. In this study, effectiveness of pre- and postharvest application of an aqueous hexanal formulation and an enhanced freshness formulation (EFF) containing hexanal and other ingredients were evaluated by monitoring changes in quality parameters during postharvest storage of greenhouse tomatoes. Tomatoes subjected to preharvest spray with EFF containing 1 mM hexanal twice a week had better colour, and firmness than untreated fruit and hexanal formulation treated fruit. EFF treated tomatoes also showed low hue angle values indicative of enhanced red colour. Preharvest spray with 1 mM hexanal twice a week resulted in higher levels of ascorbic acid and soluble solids in fruit than those subjected to EFF treatment, and the control. Postharvest dip application of harvested tomatoes in 2 mM hexanal as EFF resulted in enhanced brightness and hue angle values, reduced red colour, increased fruit firmness and ascorbic acid content after 21 days of storage, indicative of better quality. The results suggest that hexanal has the potential to enhance shelf-life and quality of greenhouse tomatoes.