Abstract:ResumoNeste estudo, verificou-se a utilização de um filme de quitosana para o controle do crescimento e produção de aflatoxinas por A. parasiticus em amendoim. Os filmes foram aplicados sobre os grãos por meio de duas metodologias (aspersão e imersão). Os grãos recobertos foram inoculados com 2,5 ml de uma suspensão contendo 1,0×106 esporos/ml e incubados a 25 o C por 7 dias. A concentração de aflatoxinas foi determinada por cromatografia em camada delgada, utilizando a técnica de densitometria. A verificação … Show more
“…To date, only a few studies reported the effect of chitosan on both growth and mycotoxin production in different fungal species. For instance, on Aspergillus flavus and Aspergillus parasiticus [37,38,39] and Alternaria alternata f. sp. lycopersici [40].…”
The objectives of the present study were to determine the combined effects of chitosan and water activity (aW) on growth and mycotoxin production in situ on the two most important Fusarium species (F. proliferatum and F. verticillioides) present on maize, and on F. graminearum, the main pathogen causing Fusarium head blight on wheat. Results showed that low-molecular-weight chitosan with more than 70% deacetylation at the lowest dose used (0.5 mg/g) was able to reduce deoxynivalenol (DON) and fumonisin (FBs) production on irradiated maize and wheat grains. Growth rates of F. graminearum also decreased at the lowest chitosan dose used (0.5 mg/g), while F. verticillioides and F. proliferatum growth rates were reduced at 0.98 aW at the highest chitosan dose used (2 mg/g). Since mycotoxins are unavoidable contaminants in food and feed chains, their presence needs to be reduced in order to minimize their effects on human and animal health and to diminish the annual market loss through rejected maize and wheat; in this scenario, pre- and post-harvest use of chitosan could be an important alternative.
“…To date, only a few studies reported the effect of chitosan on both growth and mycotoxin production in different fungal species. For instance, on Aspergillus flavus and Aspergillus parasiticus [37,38,39] and Alternaria alternata f. sp. lycopersici [40].…”
The objectives of the present study were to determine the combined effects of chitosan and water activity (aW) on growth and mycotoxin production in situ on the two most important Fusarium species (F. proliferatum and F. verticillioides) present on maize, and on F. graminearum, the main pathogen causing Fusarium head blight on wheat. Results showed that low-molecular-weight chitosan with more than 70% deacetylation at the lowest dose used (0.5 mg/g) was able to reduce deoxynivalenol (DON) and fumonisin (FBs) production on irradiated maize and wheat grains. Growth rates of F. graminearum also decreased at the lowest chitosan dose used (0.5 mg/g), while F. verticillioides and F. proliferatum growth rates were reduced at 0.98 aW at the highest chitosan dose used (2 mg/g). Since mycotoxins are unavoidable contaminants in food and feed chains, their presence needs to be reduced in order to minimize their effects on human and animal health and to diminish the annual market loss through rejected maize and wheat; in this scenario, pre- and post-harvest use of chitosan could be an important alternative.
“…Similar results were also obtained for spore germination and mycelial growth. SILVA et al (2015) found that the in vivo use of 2% chitosan reduced the spore concentration and the production of Aspergillus parasiticus in peanuts, and promoted, in vitro, morphological changes in the spores, such as swelling, larger diameter (20 μm), and absence of spicules. According to COQUEIRO; DI PIERO (2011), the exact mechanism of action on the pathogen is not yet fully understood.…”
We evaluated the efficacy of natural products in the control of papaya anthracnose, in vitro and in vivo. The in vitro experiments for evaluation of mycelial growth used a completely randomized 10 × 4 factorial design (treatments × evaluation periods) with eight replicates, with sporulation evaluated at the end of the experiment. The treatments involved the use of aqueous extract at concentrations of 5 and 15% for Syzygium aromaticum (L.) Merr. & Perry (clove), Cinnamomum zeylanicum Breym (cinnamon), and Zingiber officinalis Rox. (ginger); 1 and 3% chitosan; the fungicide Prochloraz at 100 µg.mL-1; and a control (no treatment). For evaluating conidia germination, we used six treatments with five replicates. The treatments included 7.5% of each extract (clove, cinnamon, and ginger), 1.5% chitosan, and 50 µg.mL-1 of Prochloraz. For the in vivo experiment, “Formosa” papaya “Tainung 1” was used in a completely randomized design, with six treatments and four replicates to evaluate the severity of anthracnose caused by Colletotrichum gloeosporioides. The fruits were treated by immersion for 5 min with 15% clove, cinnamon, and ginger extracts, 8% chitosan, and control with distilled water, and immersion for 2 min in Prochloraz (33.75 g a.i./100 L). The treatments with 15% clove extract and 8% chitosan were effective in all evaluations, resulting in a viable alternative to the fungicide Prochloraz. The treatments with ginger extract were less effective and those with cinnamon offered intermediate control.
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