1,721,009 research outputs found
CEPPO DI LIEVITO UTILIZZABILE PER RIDURRE LA QUANTITA’ DI ACRILAMMIDE IN UN PRODOTTO VEGETALE TRATTATO TERMICAMENTE
No full textCeppo di lievito utilizzabile per ridurre la quantità di acrilammide in un alimento trattato termicament
Use of biocontrol agents in combination with physical and chemical treatments: efficacy assessment
No full textPurpose of review: This review discusses the combination of biological control agents with physical (heat, gamma or UV-C
irradiation, controlled atmosphere) or chemical (salt additives, chitosan, natural plant products) treatments against the main
postharvest fruit diseases.
Findings: The use of biocontrol agents (BCAs) to control postharvest fruit diseases is still constrained by the lack of high levels
of disease control required in the postharvest phase (more than 95%). Their inconsistent activity is one of the main factors preventing
their routine application on fruit after harvest. Therefore, to overcome this issue, integrated strategies were explored
and continue to be one of the fields most investigated in postharvest fruit disease control, in order to achieve maximum effectiveness.
The combination of BCAs with physical and chemical treatments, including fungicides at low doses, resulted in an
increase of BCAs effectiveness against fungal diseases such as Pencillium spp., Monilinia spp., Botrytis cinerea, etc. Since the
integration of different treatments could benefit from their additive or synergic effects and improve the efficacy of each single
method.
Limitations: It is unrealistic to assume that BCAs have the same fungicidal activity as pesticides; the evaluation of their compatibility
with other methods therefore seems to be the main topic that will be developed in the near future. Nevertheless, it is
necessary to evaluate the possible detrimental effects of some treatments like gamma irradiation or essential oils on qualitative
fruit parameters in view of their commercial application. In addition, the use of low doses of fungicides cannot be applied to
organic production.
Directions for further research: Specific appropriate strategies have to be evaluated for each species and pathogen in order to
tailor a complete integrated disease management. Moreover, these integrated applications have to be investigated at commercial
levels, including during fruit handling, in order to ascertain their practical efficacy
New strategies to control brown rot caused by Monilinia spp. of stone fruit
No full textThe importance of brown rot caused by Monilinia spp. in all stone fruit growing areas is well recognized. The infection occurs in the field but the most dangerous fruit losses happen during storage and commercialization. The disease control depends mainly on integrated strategy based on cultural practices and fungicide spray programmes in the field. Among cultural practices, the sanitization of orchard by minimizing inoculum potential, reducing the risk of blossom and fruit infections is essential for brown rot management. However, the requirements in sustainable agriculture, integrated crop management and organic production are increased in the last few decades, resulting in the need to develop other methods than fungicide applications to disease control. Several studies focused on alternative strategies, defining three different approaches: i) biological control with microbial antagonists, ii) use of natural products and iii) use of physico-chemical methods. Significant progress has been achieved in the reduction of pesticide use with these methods; although a multidisciplinary methodology that integrates sanitary and alternative strategies has to be investigated more fully. The new strategy, starting from the field with agronomic interventions and the selection of cultivars tolerant to Monilinia spp. could be usefully integrated by postharvest treatments based on low risk chemical fungicides, natural antimicrobial substances and other physical means determining a sustainable approach to brown rot control
Biological control of postharvest diseases by microbial antagonists: how many mechanisms of action?
No full textThe postharvest phase has been considered an environment for successful application of biological control agents (BCAs). However, the interactions between fungal pathogen, host (fruit), and antagonist are influenced by several parameters such as temperature, oxidative stresses, oxygen composition and water activity that could determine the success of biocontrol. Knowledge of the modes of action of BCAs is essential in order to enhance their viability and increase their potential in disease control. The antagonists display a wide range of modes of action: antibiosis, competition for nutrients and space, parasitism and induction of resistance are considered the main ones. Their efficacy, however, is related to the host and the pathogen; sometimes, these mechanisms could act simultaneously, and it is therefore difficult to establish which is related to a specific antifungal action. The current review presents a brief summary of the research that has led to a better understanding of the mode of action of BCAs with particular emphasis on the most recent literature
Control of fruit postharvest diseases: old issues and innovative approaches
No full textPurpose of the review: This review focuses on the issues of fruit postharvest disease control; firstly the appearance of pathogen
isolates resistant to common fungicides followed by stricter regulatory policies that impose a reduction in their use. Emphasis
is given to the attempts to introduce effective biological control agents (BCAs) able to reduce fruit losses by an improvement
in their formulation.
Findings: At the beginning of the 1960s, treatments based on chemical fungicides as the main method of reducing postharvest
fruit losses obtained satisfactory results. However, the fungicide option for managing postharvest decays is increasingly limited;
in addition, the use of fungicides on fruit after harvest is regulated by different food protection agencies. The intense use of
fungicides in the postharvest phase has contributed to the appearance of resistant isolates, widespread in packinghouses. Nowadays,
fungicide resistance is frequently reported for the main fungal pathogens such as Penicillium, Monilinia, Botrytis, etc.
Although the use of synthetic chemical fungicides remains a primary method of controlling postharvest diseases, the global
trend appears to be shifting towards reduced use of fungicides, substituting them with alternative methods like biofungicides.
However, the great effort made by researchers, documented by many peer-reviewed publications, has been only partially compensated
by the appearance on the market of BCAs available for industrial application to control postharvest decays.
Limitations: There are several reasons for the limited diffusion of biofungicides, some relate to an intrinsic ineffectiveness of
BCAs such as their inconsistency, and the variability of the control under commercial conditions. Some are relate to their formulation
which reduces the activity of antagonists with respect to the fresh cells, the high cost of the production, and the regulatory
barriers to BCA registration in different countries that do not encourage their dissemination.
Directions for further research: The formulation process represents an important step for maintaining a high and stable BCA
efficacy. Dehydration of the product and maintenance in a dry environment is preferable to liquid formulations since antagonists
can be handled using the normal distribution and storage channels. Unfortunately, not all microorganisms are able to
survive drying conditions; they can lose viability during the drying process and storage. In order to avoid undesirable effects,
cryoprotecting media have to be assessed during freeze-drying treatments in order to conserve antagonist viability. For example,
in the case of Bacillus sp., its sporeforming ability could provide high resistance to extreme environmental conditions, making
it a good candidate for developing stable and efficient products. In addition, the introduction of BCAs in wax or oil-based
coatings can represent a useful strategy, above all for citrus fruit, papaya or mango that are treated by application of the coating
after harvest
Heat treatments effect on Cadophora luteo-olivacea of kiwifruit
Full text linkAbstract
Heat treatments represent alternative methods to fungicides to control latent fruit pathogens, such as Cadophora luteo-olivacea of kiwifruit. The study reports the efficacy of different hot water and hot air treatments (45 °, 50 °, 55 °, 65 °, and 70 °C with the duration respectively of 10, 15 and 20, 10, 65, 3 min) on the conidial and mycelial fungal isolates growth by in vitro assays. Both treatments at 70 °C were the most effective on the conidial and mycelial growth of C. luteo-olivacea isolates. On the mycelial growth, treatment efficacy was on average 88% and 71%, respectively, and on conidial growth by 100% and 91.3%. A significant reduction of xylanase and pectinase enzyme activities of the isolates was detected after hot water and air treatment (70 °C × 3 min). Both treatments showed, in most cases, the total reduction, sometimes variable with the target isolate. Hot air treatment was the most efficient treatment by reducing the skin pitting incidence in in vivo experiments, showing an efficacy of 46.6%, on average. Results show that heat treatments are effective against C. luteo-olivacea, but ‘time × temperature’ combinations remain the main challenge to develop
New Strategies to Control Brown Rot Caused by Monilinia spp. of Stone Fruit
Full text linkThe importance of brown rot caused by Monilinia spp. in all stone fruit growing areas is well recognized. The infection occurs in the field but the most dangerous fruit losses happen during storage and commercialization. The disease control depends mainly on integrated strategy based on cultural practices and fungicide spray programmes in the field. Among cultural practices, the sanitization of orchard by minimizing inoculum potential, reducing the risk of blossom and fruit infections is essential for brown rot management. However, the requirements in sustainable agriculture, integrated crop management and organic production are increased in the last few decades, resulting in the need to develop other methods than fungicide applications to disease control. Several studies focused on alternative strategies, defining three different approaches: i) biological control with microbial antagonists, ii) use of natural products and iii) use of physico-chemical methods. Significant progress has been achieved in the reduction of pesticide use with these methods; although a multidisciplinary methodology that integrates sanitary and alternative strategies has to be investigated more fully. The new strategy, starting from the field with agronomic interventions and the selection of cultivars tolerant to Monilinia spp. could be usefully integrated by postharvest treatments based on low risk chemical fungicides, natural antimicrobial substances and other physical means determining a sustainable approach to brown rot control
Potential for biocontrol of Pleurotus ostreatus green mould disease by Aureobasidium pullulans De Bary (Arnaud)
Full text linkPleurotus ostreatus, commonly known as “oyster mushroom”, is an edible fungus economically important worldwide. The green mould, caused by Trichoderma pleuroti and T. pleuroticola, is a very important fungal disease, and it is commonly controlled by the use of fungicides. The yeast-like fungus Aureobasidium pullulans is a biocontrol agent naturally found throughout a wide range of habitats. The effect of A. pullulans L1 and L8 strains on P. ostreatus, T. pleuroti and T. pleuroticola was studied in in vitro assays. Both yeast strains resulted compatible with P. ostreatus growth, and effective in reducing the T. pleuroticola and T. pleuroti colony growth. The inhibitory effect of L1 and L8 was similar in the majority of the Trichoderma-A. pullulans combinations on agar plates. Both strains were more efficient than Trichoderma in substrate colonization, and produced volatile and nonvolatile metabolites which reduced Trichoderma growth. When the activity of L1 and L8 was tested against the green mould disease of P. ostreatus under controlled conditions similar to those of a mushroom farm, only L8 was effective in controlling the disease. It showed an effect similar to that of the fungicide prochloraz against T. pleuroticola, the less aggressive pathogen, and lower than that of the fungicide against T. pleuroti, the most aggressive. The antagonism was the result of mechanisms like antibiosis and competition for space and nutrients, whereas the direct attachment of A. pullulans with hyphae of the pathogens did not play a role
Production of volatile organic compounds by Aureobasidium pullulans as a potential mechanism of action against postharvest fruit pathogens
No full textTwo Aureobasidium pullulans strains (L1 and L8), effective against some fruit postharvest pathogens were evaluated for VOCs production as a part of their modes of action towards five pathogens (Botrytis cinerea, Colletotrichum acutatum, Penicillium expansum, Penicillium digitatum and Penicillium italicum). The VOCs were assayed with a double petri dish assay against conidia germination of target pathogens. Results obtained showed that the VOCs generated by the antagonists inhibited significantly the conidia germination of all pathogens compared to the control. In particular, the conidia germination of all Penicillium was completely inhibited by VOCs produced by L1 and L8. In in vivo tests, apples and oranges were artificially inoculated with pathogen conidia and then biofumigated with VOCs emitted by both antagonists. The antagonistic treatment controlled significantly pathogen infection, confirming the results obtained in vitro tests. The best L1 and L8 VOCs activity was observed on apple inoculated with B. cinerea where the lesion diameter reduction observed was greater than the 88%. The compounds emitted by L1 and L8 strains were identified with the solid-phase microextraction (SPME)-gas chromatographic technique. Compounds as 2-phenyl, 1-butanol-3-methyl, 1-butanol-2-methyl and 1-propanol-2-methyl belonging to the group of alcohols were mainly produced for both strains, in the first 96h of growth. These compounds were confirmed by comparison with standards. The pure compounds of VOCs cited above were used to determine the EC50 values for conidia germination of pathogens. The 1-propanol-2-methyl was the VOC least active against all tested fungi, with the EC50 values over 0.8μlml-1, while the 2-phenethyl alcohol was the most active with EC50 values lower than 0.8μlml-1, except for the C. acutatum (1.97μlml-1). The present study demonstrated, for the first time, that the production of VOCs could play an essential role in the antagonistic activity of two A. pullulans strains against five fruit postharvest pathogens
Defense response against postharvest pathogens in hot water treated apples
Full text linkHot water treatment (HWT) has been demonstrated to be a safe and effective method to control postharvest diseases. In the present study, the effect of HWT (45 °C for 10 min) was investigated on the response of apple fruit against Botrytis cinerea, Colletotrichum acutatum and Neofabraea vagabunda infections. In vivo experiments were conducted with apples treated with HW and then inoculated with pathogen spore suspensions 0, 3, 6 and 24 h after the treatment. In vitro experiments were carried out in order to investigate the HWT effect on the pathogenesis enzyme activities of the three pathogens. These assays were conducted with the crude protein extracts (CPEs) derived from the hot water treated apples. A significant reduction of rot incidence was observed in fruit inoculated at 6 h (B. cinerea 22.7% and C. acutatum 11.0%) and 3 h (N. vagabunda 68.8%) after HWT with respect to the controls (22.0, 18.5 and 19.67 mm, respectively). CPEs extracted from hot water treated fruit inoculated at 6 h and 3 h showed the highest conidia germination inhibition (B. cinerea 85.6%; C. acutatum 52.7% and N. vagabunda 83.1%) with respect to the controls (74.0, 71.0 and 90.3% of conidia germination, respectively). A significant reduction of pathogenesis enzyme activities of the three pathogens was detected when pathogens were exposed to CPEs derived from hot water treated apples. The results showed that HWT can stimulate a defense response on apple against some postharvest pathogens
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