Control Of Postharvest Decay Research Articles

Decay control in the postharvest system: Role of microbial and plant volatile organic compounds

Significant postharvest losses occur during the supply chain of fresh produce. Postharvest decay is one of the main factors that determines losses and compromises the quality of fruit and vegetables. Traditionally postharvest decay control is achieved using chemical fungicides; however, the important concerns relating to environmental and human health require the development of novel methods for the control of postharvest decay. Furthermore, the consumer demand and the purchasing power are higher for fresh produce that are free from pesticide application. This review highlights the research literature based information on the application of microbial and plant volatile organic compounds (VOCs) to control postharvest decay, their practical applications in postharvest systems and the future perspectives. The volatile nature of VOCs could be potentially employed with success as gaseous treatments in a process defined ‘biofumigation’. Plant-produced volatiles including among others, aldehydes such as acetaldehyde, 2-E-hexenal and benzaldehyde, alcohols such as ethanol and acetic acid, essential oils (EOs) and isothiocyanates (ITCs) and microbial volatile organic compounds have been recognised as potential substances in preventing pathogenic infections in many horticultural commodities. However, some issues have to be well elucidated in order to admit these substances in a large-scale application to improve the competitiveness of the fresh produce at the quality stringent EU, USA, and the Japanese markets. The main concern are related to the registration process, but also VOCs degradation and residues in fruit, formulation and organoleptic impact, are aspects that have to be thoroughly considered prior to commercialisation of the selected VOC. Furthermore, VOCs could have an effective role for an eco-chemical approach in postharvest disease control since these biobased products, if compared to conventional ones, can offer clear environmental benefits due to their renewability, biodegradability and hypotoxicity.

Integrated control of postharvest decay on sweet orange fruits by hot water and Sodium Carbonate (Na2CO3) applications

Integrated control of postharvest decay on sweet orange fruits by hot water and sodium carbonate (Na2CO3) applications during subsequent storage at 28°C was investigated and the effect of such treatment on internal quality attributes of orange fruits determined. Mature sweet orange fruits without bruises were selected and washed in 2% sodium hypochlorite solution for 5 minutes before treatment. For ordinary sodium carbonate treatment (without hot water), selected fruits were separately immersed for 150 seconds in a water bath containing 2% (w/v) and 4% (w/v) sodium carbonate (Na2CO3) solutions. In another experiment, selected fruits were immersed for 150 seconds in a water bath containing hot water and sodium carbonate solution. Sodium carbonate concentrations at 2% (w/v) and 4% (w/v) in 45°C hot water temperature were tested. After treatment, the fruits were rinsed, allowed to air dry and then placed inside plastic buckets and stored at 25°C and 88% relative humidity and assessed weekly for mould infection. Result showed that fruits treated with 4% ordinary Na2CO3 concentration had no incidence of decay during the first week of storage. However, untreated fruits and fruits treated with ordinary 2% Na2CO3 concentration recorded 20.00% disease incidence in the first week of storage. The percentage decay of fruits later increased to 44.16±10.83 in all the fruits treated with 2% Na2Co3 concentration by week two and continued till third week when they were completely diseased, having 100% decay incidence. The causal organisms in the decaying fruits were Penicillium digitatum and Phytophthora palmivora. However, fruits treated with 2% Na2CO3 concentration in 45oC hot water recorded 0% decay incidence throughout storage duration which lasted for 6 weeks and as such implied that all the treated fruits were diseased free.

Active packaging containing encapsulated carvacrol for control of postharvest decay

Roughly, one-third of the food produced globally for human consumption is lost or wasted. These losses occur at all stages of the food value chain and across all types of food. Active packaging already plays a vital role in preventing wastage and further innovation is imperative to streamlining the food supply chain. Herein, we present an antimicrobial packaging based on polyamide (Nylon 6), containing a model essential oil (carvacrol). The volatile carvacrol molecules are encapsulated with Halloysite nanotubes (HNTs), which are naturally occurring aluminosilicate. The resulting polyamide films had an outstanding in vitro antifungal properties, with a broad spectrum of inhibitory activity against a wide range of fungal molds: Alternaria alternata, Botrytis cinerea, Penicillium digitatum, Penicillium expansum and Aspergillus niger. Furthermore, the active polyamide-based plastic bags were used for fresh produce packaging and their fungicidal and/or fungistatic effects on postharvest pathogens of cherry tomatoes, lychee and grapes were investigated. These in vivo experiments have resulted in reduced decay development and significantly extended shelf life. The presented technology holds a great potential for the development of custom-made active packaging for the food and postharvest industries, in a global effort to reduce food loss and waste.

Microemulsification of clove essential oil improves its in vitro and in vivo control of Penicillium digitatum

Clove essential oil (CEO) is a promising alternative to chemical fungicides for postharvest decay control. However, relatively high concentrations required for in vivo microbial growth inhibition limit its application. Hence, this study aimed to strengthen the antifungal activity of CEO by loading it in microemulsion system. Two CEO microemulsions (ME-1, CEO/ethanol/Tween 80 = 1:2:7; ME-2, CEO/ethanol/Tween 80 = 1:3:6) were evaluated their antifungal activity against Penicillium digitatum in vitro and in navel oranges. Microemulsification of CEO caused a reduction of MIC (minimum inhibitory concentration) from 0.50 μl/ml to 0.25 μl/ml, while the MFC (minimum fungicidal concentration) remained unchanged at 0.50 μl/ml, indicating enhancement of only fungistatic activity. The decay incidence of navel oranges treated with ME-1 and ME-2 was significantly (p < 0.05) reduced by 34.51% and 20.93%, respectively, in comparison to that of pure oil treatment after 5 days' storage at 25 °C. In the vapor phase, CEO microemulsions had the best control of lesion diameter and decay development. Additionally, the improved antifungal activity of CEO microemulsions may be related to their stronger ability to suppress spore germination and germ tube elongation of P. digitatum. The enhanced control of postharvest green mold of navel oranges by CEO after microemulsification can broaden its application in food industry.

Effect of harpin on control of postharvest decay and resistant responses of tomato fruit

Postharvest decay caused by fungal pathogens is responsible for significant economic losses in the tomato industry. Induction of disease resistance in harvested horticultural crops is an approach to controlling postharvest losses that is being actively investigated. In the current study, the effects of harpin (a bacterial hypersensitive response elicitor) on gray mold and black rot caused by Botrytis cinerea and Alternaria alternata, respectively, in tomato fruit were investigated. Harpin effectively controlled gray mold and black rot on inoculated tomato fruit, as well as natural infection. Harpin treatment at 90mgL−1 induced the transcript expression of defense-related genes including chitinase, β-1,3-glucanase and phenylalanine ammonia-lyase based on RT-qPCR analysis, increased the activity of these enzymes, and the content of total phenolic compounds and lignin in tomato fruit. Moreover, harpin did not demonstrate any fungicide effect on B. cinerea or A. alternata in vitro. These findings suggest that the effect of harpin on postharvest diseases was attributed to the elicitation of resistant responses, and harpin treatment may represent a promising strategy for managing postharvest decay of tomato fruit.

Preharvest treatments with chitosan and other alternatives to conventional fungicides to control postharvest decay of strawberry

The effectiveness of the control of postharvest decay of strawberry (Fragaria×ananassa, ‘Alba’ and ‘Romina’ cvs.) fruit following field applications of chitosan, laminarin, extracts of Abies spp., Polygonum spp., and Saccharomyces spp., an organic acids and calcium combination, and benzothiadiazole, were compared with a fungicide strategy. These compounds were sprayed every 5 days on the strawberry canopy, from flowering to ripening, in 2012 and 2013. The treatments with alternative compounds provided ∼30% reduction in postharvest decay of strawberry compared to the water-treated controls, mainly against gray mold and Rhizopus rot, and without negatively affecting fruit color and firmness. Chitosan and benzothiadiazole were the most effective alternative treatments. Preharvest spraying with these alternative treatments can complement the use of conventional fungicides in the control of postharvest decay of strawberry fruit, especially when disease pressure is low.

Combining an antagonistic yeast with harpin treatment to control postharvest decay of kiwifruit

Integrated management, utilizing different non-chemical methods, is an approach to controlling postharvest losses that is being actively investigated. In the present study, the use of an antagonistic yeast, Candida diversa, combined with harpin (a hypersensitive response elicitor) treatment was evaluated for their ability to prevent infection of kiwifruit after they were artificially inoculated with Botrytis cinerea or Penicillium expansum. Natural infection of treated fruit was also assessed. As a standalone treatment, C. diversa or harpin significantly reduced gray (B. cinerea) and blue mold (P. expansum) infections on kiwifruit, relative to the untreated control fruit, and also reduced the level of natural infection. The combination of C. diversa and harpin treatment, however, provided a superior level of control on fruit, relative to either treatment alone. Harpin did not negatively impact C. diversa growth in kiwifruit wounds. Treatment of kiwifruit with C. diversa and harpin alone or in combination also induced the activity of enzymes involved in defense response, such as polyphenol oxidase, peroxidase and superoxide dismutase. Harpin alone or in combination with C. diversa enhanced accumulation of lignin content in kiwifruit as well. The mode of action by which harpin enhanced biocontrol efficacy of C. diversa may be partially attributed to the elicitation of defense response in kiwifruit. Integrating the use of antagonistic yeast with harpin treatment has potential as an effective method for the control of postharvest decay in kiwifruit.

Effects of chitosan on control of postharvest blue mold decay of apple fruit and the possible mechanisms involved

The effectiveness of chitosan in controlling blue mold decay of apple fruit caused by Penicillium expansum and the possible mechanisms involved were investigated in the present study. The application of chitosan significantly reduced the blue mold decay of the postharvest apple fruit and patulin accumulation, and no negative effect of chitosan treatment on fruit quality was observed after 15 days of storage. Changes of protein expression profiles of apple fruit upon chitosan treatment were analyzed by two-dimensional electrophoresis and 20 differentially expressed proteins were identified by mass spectrometry analysis. Several proteins involved in defense, carbohydrate catabolism and protein biosynthesis were up-regulated by chitosan treatment. Activated defense response and increased energy supply in chitosan treated fruit may constitute the molecular basis for increased resistance to the possible future pathogen infection. This study contributes to a better understanding of the cellular events in apple fruit under chitosan treatment in view of a promising alternative in controlling postharvest disease.

Enhanced control of postharvest citrus fruit decay by means of the combined use of compatible biocontrol agents

Fourteen Pseudomonas spp. and three Trichoderma spp. strains were tested in vitro for their antagonistic properties against Penicillium digitatum, the causal agent of citrus green mold. Bacterial and fungal strains strongly inhibited the pathogen growth in vitro on PDA and on a citrus-based medium. Inhibitory effects were increased when Pseudomonas and Trichoderma strains were applied in combination. Inhibitory effects were also increased by mixtures of Pseudomonas cells and Trichoderma atroviride P1 culture filtrates. On the opposite, bacterial and fungal filtrates in mixture never induced an improved efficacy, thus indicating that the presence of living bacterial cells was required for a synergistic effect. Accordingly, incidence and severity of disease on orange cv. Tarocco and lemon cv. Femminello were consistently reduced when Pseudomonas and Trichoderma strains were applied 72h before challenging P. digitatum. Pseudomonas syringae strains were the most effective and several combinations had a biocontrol activity higher than one of the each antagonistic microorganism applied alone. The treatments comprising six P. syringae in mixture with Trichoderma strains T22, P1 and T34 were the most effective, with 80–100% control of green mold. The development of green mold decay was also effectively inhibited in small-scale dip-treatments, either by single applications or by their mixtures. These experiments suggest that the combination of Pseudomonas spp. and Trichoderma spp. strains could be considered as a promising mean for the control of citrus green mold decay, supporting the concept that an improved disease control is given by the combined action of the two agents.

Effect of the Yeast Rhodosporidium paludigenum on Postharvest Decay and Patulin Accumulation in Apples and Pears

The effect of a strain of marine yeast Rhodosporidium paludigenum on postharvest blue mold and patulin accumulation in apples and pears stored at 23°C was evaluated. The occurrence and severity of apple and pear decay caused by Penicillium expansum were significantly inhibited by R. paludigenum. However, the application of the yeast at a high concentration (108 cells per ml) enhanced patulin accumulation after 7 days of storage; the amount of patulin increased 24.2 times and 12.6 times compared to the controls in infected apples and pears, respectively. However, R. paludigenum reduced the patulin concentration in the growth medium by both biological degradation and physical adsorption. Optimal in vitro patulin reduction was observed at 30°C and at pH 6.0. R. paludigenum incubated at 28°C was tolerant to patulin at concentrations up to 100 mg/liter. In conclusion, R. paludigenum was able to control postharvest decay in apples and pears and to remove patulin in vitro effectively. However, because the yeast induced patulin accumulation in fruit, the assessment of mycotoxin content after biological treatments in postharvest decay control is important. R. paludigenum may also be a promising source of gene(s) and enzyme(s) for patulin degradation and may be a tool to decrease patulin contamination in commercial fruit-derived products.

USE OF RESISTANCE INDUCERS TO CONTROL STORAGE DECAY OF SWEET CHERRY

Postharvest decay can cause severe losses of sweet cherry in storage, and the use of synthetic fungicides is not allowed after harvest on this crop. Therefore, the effectiveness of alternative means for the control of postharvest decay of sweet cherry was tested in vitro and in vivo. When amended to potato dextrose agar, oligosaccharides, benzothiadiazole, chitosan, calcium plus organic acids (COA), and nettle macerate reduced the growth of Monilinia laxa, Botrytis cinerea and Rhizopus stolonifer. Treatments of sweet cherries three days before harvest or soon after harvest with oligosaccharides, benzothiadiazole, chitosan, COA, nettle extract, fir extract, laminarin, or potassium bicarbonate reduced brown rot, gray mold, Rhizopus rot, Alternaria rot, blue mold, and green rot of cherries kept 10 d at 20±1°C, or 14 d at 0.5±1°C and then exposed to 7 d of shelf life at 20±1°C. Among these resistance inducers, when applied either preharvest or postharvest, chitosan was one of the most effective in reducing storage decay of sweet cherry, and its antimicrobial activity in vitro and in field trials was comparable to that of the fungicide fenhexamid. Benzothiadiazole was more effective when applied postharvest than with preharvest spraying. These resistance inducers could represent good options for organic growers and food companies, or they can complement the use of synthetic fungicides in an integrated disease management strategy.

Integration of Lactobacillus plantarum A7 with thyme and cumin essential oils as a potential biocontrol tool for gray mold rot on strawberry fruit

Chemical fungicides have been intensively used in the control of postharvest decay in fruit in postharvest conditions; nevertheless, continuous use of these fungicides has faced two major obstacles: development of pathogen resistance to many key fungicides, and public knowledge on the health and environmental hazards of these compounds. This study evaluated the efficacy of Lactobacillus plantarum A7, thyme (Thymus vulgaris L.) and cumin (Cuminum cyminum L.) essential oils and the combination of these three elements as postharvest biocontrol agents against Botrytis spp. on strawberry fruit. Thyme oil had a remarkable antifungal effect against Botrytis spp. in vitro, whereas an inhibitory effect of cumin oil was achieved in higher concentrations. With thyme oil (2h after artificial inoculation of the fruit), among three tested concentrations, only the 200μL/L concentration showed an inhibitory effect on strawberries against Botrytis spp. (91.97%), while higher concentrations of cumin oil were required to prevent decay significantly. Both combinations of L. plantarum+ cumin oil and L. plantarum+ thyme oil completely inhibited the mycelia growth of the pathogens in vitro. Results showed that the combined treatments of strawberry fruit with L. plantarum+ cumin oil (50μL/L) and L. plantarum+ thyme oil (100μL/L) resulted in remarkably improved control of Botrytis infections, in comparison to the stand-alone application of L. plantarum A7 or essential oils. Quality (i.e. pH, acidity and ascorbic acid content) and sensory attributes of the strawberry fruit were better in the case of using cumin compared to thyme oil, when a combination of L. plantarum A7 and essential oils was used. This study has demonstrated that the integration of L. plantarum A7 with thyme and cumin essential oils is a potential biocontrol tool as a biofungicide in postharvest stage.

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 2min. 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 2min) 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.

Control of postharvest grey mould decay of nectarine by tea polyphenol combined with tea saponin

The control efficacy of tea polyphenol (TP) in combination with tea saponin (TS) against nectarine grey mould decay caused by Botrytis cinerea and the underlying mechanism were investigated. The in vitro experiments showed that both TP and TS inhibited the mycelial growth in a dose-dependent manner, and their combinations exhibited synergistic antifungal interactions with the synergistic ratios (SR) exceeding 1·5. The in vivo experiments showed that disease incidence and lesion diameter of grey mould of inoculated fruit were significantly lowered after being treated with the combination of TP and TS; furthermore, the activities of phenylalanine ammonia-lyase (PAL), peroxidase (POD), polyphenol oxidase (PPO), chitinase and β-1,3-glucanase of inoculated fruit as well as the contents of total phenolic and lignin were significantly induced, the respiration rate of inoculated fruit was significantly decreased and therefore the quality decrease was accordingly retarded. These results revealed that TP in combination with TS could control grey mould of inoculated nectarines and their mechanism of action might be attributed to their active components, the induction of defensive system and the regulation of respiration. This study demonstrates that the combination of TP and TS has exhibited synergistic antifungal interactions against Botrytis cinerea, and it suggests that their combination may be useful and effective agents for the control of nectarine grey mould decay. Such natural products therefore represent a promising alternative to synthetic fungicides in the control of nectarine postharvest diseases.

Impact of carboxymethyl cellulose coating enriched with extract of Impatiens balsamina stems on preservation of ‘Newhall’ navel orange

A new approach to the control of postharvest decay, while maintaining fruit quality, has been implemented by the application of extract of Impatiens balsamina L. stems, a commonly used traditional Chinese medicine, amended coatings to ‘Newhall’ navel orange (Citrus sinensis L., Osbeck). After harvest, navel oranges were dipped in amended coating and then the samples were stored at 5°C and 90–95% RH after being dried naturally. The data suggested that the coating treatment, respectively, reduced the decay rate and weight loss of fruit from 10.2% to 6.1% and from 6.33% to 2.91% after 100 days storage, with none deleterious effects on fruit quality such as soluble solids content (SSC), titratable acidity (TA) and asorbic acid content (AsA). Moreover, the activities of scavenger antioxidant and defense enzymes, including peroxidase (POD), superoxide dismutase (SOD), chitinase (CHI) and β-1,3-glucanase (GLU), were also increased by the coating treatment. It indicates that the film may be an effective and safe alternative preservative for navel orange.

Postharvest Control of Green Mold Decay of Citrus Fruit Using Combined Treatment with Sodium Bicarbonate and Rhodosporidium paludigenum

The objective of this study was to analyze the impact of the marine yeast Rhodosporidium paludigenum and sodium bicarbonate (SBC) treatments applied separately or in combination to control green mold of two cultivars of citrus fruit (Citrus reticulata Blanco cv. Subcompressa and C. reticulata Blanco cv. Ponkan) caused by Penicillium digitatum. In the assay of C. reticulata Blanco cv. Subcompressa, R. paludigenum at 107 cells/mL significantly (P < 0.05) reduced green mold incidence compared to the control, and the combination of 107 cells/mL R. paludigenum and 5 % SBC was as effective as fungicide (500 ppm Fungaflor). In the assay of C. reticulata Blanco cv. Ponkan, the treatment with R. paludigenum at 108 cells/mL and 2 % SBC were equally effective and significantly (P < 0.05) reduced the decay incidence. Moreover, the combination of the two treatments completely eliminated the decay incidence, matching the effectiveness of fungicide. This work demonstrated that proper combination of R. paludigenum and SBC can be an alternative to synthetic fungicides for the control of postharvest green mold decay of citrus.

Effect of microencapsulated essential oils on storage life and quality of strawberry (Fragaria ananassa cv. Camarosa)

Introduction Decay is an important factor that limits the storage life of strawberries after harvest and is responsible for significant economic losses. Control of postharvest decay in strawberry fruit has been mostly dependent on the use of fungicides. However, because of the negative effects of fungicides on the environment and human health, and the development of fungicide resistance by pathogens, there is an urgent need to seek alternatives. Objectives In this study the effect of Rosmarinus officinalis and Thymus vulgaris microencapsulated essential oils on shelf-life of strawberry var camarosa fruit was assayed. Methods Four different treatments were used: T1, control, none microencapsulation; T2, 0.2gr Rosmarinus officinalis oil microencapsul (ROM); T3, 0.2gr Thymus vulgaris oil microencapsul (TOM); T4, 0.1gr Rosmarinus officinalis oil microencapsul addition 0.1 gr Thymus vulgaris oil microencapsul (RTOM). Results All tested treatments indicated a significant delay in the change of weight loss, titrable acidity, total soluble solids, decaying percentage and firmness in strawberry fruits of experimental set than the control set. The significant impact of treatment is found on the least decay percentage in the order of fruits treated with T2, T3, T4, presumably because of the difference found in the release pattern of the oils could be due to the different hydrophilic characteristics. Conclusion Hence, it could be concluded that postharvest treatment with microencapsulated essential oils has the potential to control decaying incidence, prolong the storage life and preserve valuable attributes of postharvest strawberry, presumably because of its effect on inhibition of ripening and senescence processes and have antifungal activities.

Fungistatic action of Aureobasidium pullulans on Penicillium expansum in “Rocha” pear: implications for oxidative stress during fruit storage

In “Rocha” pear, postharvest diseases, blue and grey moulds caused by Penicillium expansum and Botrytis cinerea, respectively, are particularly important. The control of postharvest decay has been based on the use of synthetic fungicides. However, there are risks to consumer health and the environment. In previous work, the antagonistic activity of the yeast-like fungus Aureobasidium pullulans (isolated from the surfaces of fruit, leaves and branches of “Rocha” pear trees), when applied as a wound treatment, was able to significantly reduce postharvest decay caused by P. expansum under storage conditions, and during simulated shelf-life. For more effective prevention and reduction of postharvest diseases in fruits it is necessary to understand the complex interactions in biological control between host, pathogen and antagonist, for which information is currently lacking. Thus, the aims of this study were to evaluate the biocontrol activity of the yeast-like fungus A. pullulans against P. expansum and to elucidate the resistance mechanism involved in the antagonistic activity of A. pullulans to oxidative stress. Fruits of Pyrus communis L. cv. Rocha were stored at −0.5°C, 95% relative humidity for 5.5 months. Fruit maturity was measured in terms of pericarp colour, sugar analysis, Streif index and flesh firmness. Assays of carbon dioxide and ethylene, electrolyte leakage, ascorbate, glutathione and antioxidant enzymes were used to evaluate oxidative stress. Furthermore, malondialdehyde, considered as a final product of lipid peroxidation, and the levels of hydrogen peroxide and methanesulfonic acid were determined and linked to oxidative stress impact on the lipid phase of cell membranes. During a 5-month period, fruit firmness, value of hue angle and colour, and Streif index changed significantly. Sucrose content decreased whereas fructose, glucose and sorbitol levels increased. After inoculation with A. pullulans and infection with P. expansum, a fungistatic, rather than fungicidal, effect was detected from 2.5 months onwards. Three months after storage, the higher superoxide dismutase activity and hydrogen peroxide levels caused by A. pullulans plus P. expansum were possibly associated with additional unsaturated fatty acids, as reflected by increased acyl lipid peroxidation. After five months of storage, in tissues inoculated with A. pullulans followed by infection with P. expansum, oxidative stress was linked to a general increase in the antioxidant peroxidase system activity. Glutathione and ascorbate content also increased along with the loss of cellular membrane selectivity. The results revealed a fungistatic effect of A pullulans on P. expansum. The prevalence of oxidative stress on “Rocha” pear wounds during the storage period was characterized, taking into account the interactions between A. pullulans and P. expansum. The information gained forms the basis for a biocontrol strategy, and the development of successful formulations for application in the orchard and after harvest. This strategy could eradicate and protect fruit against postharvest diseases, and is thus a promising alternative to the use of synthetic pesticides, being safe for the environment and for human health.

EVALUATION OF PLANT ESSENTIAL OILS FOR CONTROL OF POSTHARVEST BROWN AND GRAY MOLD ROTS ON APRICOT

ABSTRACTIn this study, antifungal activities of Thymus vulgaris L., Eugenia caryophyllata L., Cinnamomum zeylanicum Blume and Carum copticum L. essential oils against Monilinia fructicola and Botrytis cinerea, two important postharvest pathogens of stone fruit, were investigated under in vivo studies. Results showed that the essential oil treatments, especially T. vulgaris and E. caryophyllata oils, had a good antifungal activity in reduction of both disease incidence and disease severity of brown and gray mold rots caused by M. fructicola and B. cinerea on apricots, respectively. Gas chromatography (GC) and GC/mass spectrometry analysis of tested essential oils showed that thymol (37.55%), eugenol (48.76%), cinnamaldehyde (90.33%) and thymol (50.88%) were the main components of T. vulgaris, E. caryophyllata, C. zeylanicum, C. copticum oils, respectively. Application of C. copticum and E. caryophyllata oils on apricot fruit showed a significant effect on fruit quality retention as evaluated with weight loss (%), fruit firmness, total soluble solids, titratable acidity and maturity index in sensory parameters. These results revealed that T. vulgaris and E. caryophyllata oils could be natural alternatives to fungicides in the control of M. fructicola and B. cinerea infections.PRACTICAL APPLICATIONSBecause of problems related to synthetic fungicide application, calls for research into new potential safe strategies for control of postharvest decay in crops. Plant products, especially essential oils, are one of the most promising groups of natural compounds for development of indigenous nature, nonmammalian toxicity and antimicrobial agents and their employment for the control of different postharvest pathogens is also well documented. The results of in vivo (cold storage of fruits) experiments, in this study, showed that essential oil treatment had significant effects on fungal growth. The number of infected fruits and disease severity were reduced in oil‐treated fruit and with increase of essential oil concentration the fungal growth decreased. Therefore, these compounds could be an alternative to chemical fungicides for the control of postharvest fungal diseases on apricot fruits. In addition, the application of plant essential oils could be named as new safe method for control of agricultural products.

Effects of chitin and its derivative chitosan on postharvest decay of fruits: a review.

Considerable economic losses to harvested fruits are caused by postharvest fungal decay during transportation and storage, which can be significantly controlled by synthetic fungicides. However, considering public concern over pesticide residues in food and the environment, there is a need for safer alternatives for the control of postharvest decay to substitute synthetic fungicides. As the second most abundant biopolymer renewable source in nature, chitin and its derivative chitosan are widely used in controlling postharvest decay of fruits. This review aims to introduce the effect of chitin and chitosan on postharvest decay in fruits and the possible modes of action involved. We found most of the actions discussed in these researches rest on physiological mechanisms. All of the mechanisms are summarized to lay the groundwork for further studies which should focus on the molecular mechanisms of chitin and chitosan in controlling postharvest decay of fruits.