Original Research Article Application of Chitosan and essential oils as alternatives fungicides to control green and blue moulds of citrus fruits (original) (raw)
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Effectiveness of Postharvest Treatment with Chitosan to Control Citrus Green Mold
Agriculture, 2016
Control of green mold, caused by Penicillium digitatum, by fungicides raises several problems, such as emergence of resistant pathogens, as well as concerns about the environment and consumers' health. As potential alternatives, the effects of chitosan on green mold disease and the quality attributes of citrus fruits were investigated. Fruits were wounded then treated with different concentrations of chitosan 24 h before their inoculation with P. digitatum. The results of in vitro experiment demonstrated that the antifungal activity against P. digitatum was improved in concert to the increase of chitosan concentration. In an in vivo study, green mold was significantly reduced by chitosan treatments. In parallel, chitinase and glucanase activities were enhanced in coated fruits. Evidence suggested that effects of chitosan coating on green mold of mandarin fruits might be related to its fungitoxic properties against the pathogen and/or the elicitation of biochemical defense responses in coated fruits. Further, quality attributes including fruit firmness, surface color, juice content, and total soluble solids, were not affected by chitosan during storage. Moreover, the loss of weight was even less pronounced in chitosan-coated fruit.
Journal of the science of food and agriculture, 2015
The ongoing postharvest loss in citrus fruits, due to fungal infection, is a chronic economic and agricultural problem. Most of citrus damages are caused by Penicillium spp., e.g. green mold by P. digitatum and blue mold by P. italicum. Fungal chitosan, from Mucor rouxii, and plant extracts from cress seeds, olive leaves, pomegranate peels and senna pods, were evaluated as antifungal agents against the phytopathogenic fungi, P. digitatum and P. italicum, using in vitro qualitative and quantitative assays. The entire natural agents exhibited potent antifungal activity; the most powerful agent was cress (Lepidium sativum) seed extract and the following was pomegranate (Punica granatum) peel extract. Fungal chitosan had also a remarkable fungicidal potentiality using both evaluation assays. P. digitatum was generally more resistant than P. italicum toward all examined agents. The incorporation of each individual natural agent in coating material resulted in great reduction in fungal gr...
Journal of Food Science, 2012
Chitosan coatings, containing or not essential oils (bergamot, thyme and tea tree oil), were applied to oranges (cv. Navel Powell). Antifungal effect was evaluated by applying coatings before and after inoculating the fruit with Penicillium italicum CECT 2294 (10 5 spores/mL), preventive and curative treatments, respectively. The effect of coatings on the quality parameters (acidity, pH, soluble solids, juice percentage, weight loss, firmness, color parameters, and respiration rate) was controlled for the different oranges samples throughout the cold storage time. Preventive antimicrobial treatments with coatings containing tea tree oil were the most effective with a reduction of the microbial growth (expressed as the percentage of infected samples) of 50%, as compared to the uncoated samples. The coatings did not lead to any relevant changes in the development of the sample quality parameters throughout the cold storage, except for a slightly reduced loss of both weight and firmness when the coatings contained bergamot oil.
Journal of Agricultural Science, 2014
Effect of water-soluble chitosan (WSC) on green mould disease caused by Penicillium digitatum P4 was investigated in vitro and in vivo. Results of the experiments showed that P. digitatum P4 growth was much inhibited by WSC and inhibitory effect increased as WSC concentration increased. In vitro test results indicated that complete inhibition of spore germination and mycelial growth were observed in the medium containing 1 mg/ml WSC. In the in vivo study, WSC treatments significantly reduced disease incidence and lesion diameter of green mould disease on orange fruits. After 8 days of inoculation, the lesion diameter of orange fruits coated by 0.5%, 1%, 1.5% and 2% WSC were 5.49 cm, 5.01 cm, 3.22 cm and 1.87 cm, respectively, which smaller than that of control fruits. Biochemical experiments demonstrated that the activities of the main defense-related enzymes in flavedo tissue including chitinase and β-1,3-glucanase were enhanced by both P. digitatum P4 infection treatment and challenged with P. digitatum P4 and treated with WSC treatment. However, these enzymes of samples inoculated with P. digitatum only were lower than samples inoculated with P. digitatum P4 and treated with 2% WSC concentration. These findings suggest that the in vitro and in vivo effects of WSC on controlling green mould disease may be associated with direct antifungal activities and the elicitation of biochemical defense responses in fruit.
Summa Phytopathologica, 2011
Citrus fruits are affected by the black spot disease caused by the fungus Guignardia citricarpa. Chitosan can be used as covering for fruits and may delay the ripening process and inhibit the growth of some fungi. Thus, the control of citrus black spot using chitosan and the fungicides thiabendazole and imazalil was assessed in addition to the physicochemical quality of 'Pêra Rio' oranges. The oranges were immersed into chitosan, thiabendazole or imazalil, and in chitosan mixed with both fungicides. The fruits were then stored at 25 °C, 80% RH, for 7 days and, after this storage period, subjected to physicochemical analyses. Chitosan in association with the fungicides reduced black spot in 'Pêra Rio' oranges and delayed the change in the orange skin colour from green to yellow during the postharvest storage. Total soluble solids, titratable acidity, pH, ascorbic acid content and ratio were not influenced by the treatments. Thus, chitosan applied with the fungicides t...
2014
Considering the viability and the antimicrobial potential of secondary metabolites synthetized by plants, this work aimed at evaluating the effect of natural vegetal products on orange green mold. Fruits of orange, naturally infected with P. digitatum, were submitted to fumigation with 2mL of essential oil of Citrus aurantium ssp. bergamia and Citrus aurantium ssp. sinensis and also to immersion in citric extracts at a concentration of 2% and 4% (fruits immersed in distilled water constituted the control treatment). The treated fruits remained in room conditions (25 2ºC and 85 5% R.H.) for a period of 12 days. By analyzing the results, we observed lower incidence of the pathogen over the fruits that were submitted to treatments with natural products, being that treatments with citric extract at 2% and 4% and the treatment with essential oil of C. aurantium ssp. sinensis did not differ significantly among them, but there was a significant different among them and the treatment wi...
A new approach to the control of postharvest pathogens, while maintaining fruit quality, has been implemented by the application of essential oil amended coatings to citrus. This approach eliminates the need for synthetic fungicides, thereby complying with consumer preferences, organic requirements and reducing environmental pollution. In vitro studies indicated that the essential oils and some of the terpenoid components tested were active against Penicillium digitatum. In a series of subsequent semi-commercial and commercial trials, Mentha spicata and Lippia scaberrima essential oils, as well as pure (d)-limonene and R-(−)-carvone were incorporated into a variety of commercial citrus coatings. These amended coatings were applied postharvest to 'Tomango' oranges in the absence of the standard fungicide dip. Excellent disease control was achieved with the amended coatings, while measured quality parameters indicated that overall fruit quality was maintained. Moreover, moisture loss was decreased significantly in fruit treated with essential oil enriched coatings. The efficacy of amended coatings as a viable alternative or supplement to existing fruit protection strategies was demonstrated in a commercial trial.
Green and blue moulds, due to the pathogenic action of Penicillium digitatum and Penicillium italicum respectively are the main cause of orange losses during storage. Under Mediterranean climate conditions, both together are responsible for 80% of total postharvest citrus fruit decay. They occur in all citrus growing countries, worldwide and may attack the fruits in packinghouses, in transit, in storage and in the market. Tested of some alternative fungicides i. e. Ascorbic acid, Benzoic acid, Citric acid and Potassium sorbate at 500, 1000, and 1500 ppm conc. on growth rate (cm) of P. digitatum and P. italicum indicated that, all tested alternative fungicides were found to be reduced significantly the growth rate of P. digitatum and P. italicum compared with untreated (control). Data also presented that; Benzoic acid was the most effective than the others followed by potassium sorbate and Ascorbic acid while; citric acid was less. 1500 ppm concentration was more effective on the fungal growth rate than other concentrates. Also, both 1000 and/or 1500 ppm was better conc. for reducing the entire fungal growth rate compared with 500 ppm. P. italicum was the most affecting growth rate followed by P. digitatum comparing with non-treated control.