RESUMO
The influence of water activity (aw) on deoxynivalenol accumulation in wheat at 25°C was studied. Gnotobiotic grains were conditioned at different aw levels, inoculated with a toxigenic Fusarium graminearum strain, and incubated for ten weeks. The highest accumulation of deoxynivalenol (1130 ug/kg) was detected at aw 0.980. At aw 0.945 and 0.925 the maximum quantities of toxin accumulated were 113 ug/kg and 93 ug/kg respectively. Deoxynivalenol was not detected in the substrate at aw 0.900. Results suggest that intermediate aw levels (0.97 - 0.92) are particularly critical at post harvest time because those are conditions under which deoxynivalenol production is most likely to be initiated naturally.
RESUMO
The influence of water activity (aw) on both Penicillium citrinum growth and citrinin accumulation in wheat was studied. Wheat conditioned at different levels of aw and inoculated with a citrinin producer strain was incubated at 30 degrees C for 2 months. Fungal growth was assessed by microscopic examination. P. citrinum grew down to aw 0.775. Citrinin was not detected in the substrate at aw 0.800 and lower. As aw increased the toxin was detected earlier and the maximum accumulation increased markedly (65 microg/kg at aw 0.810, 460 microg/kg at aw 0.825 and 22 mg/kg at aw 0.885). Citrinin concentration declines rapidly after reaching the maximum at each aw level.
Assuntos
Citrinina/biossíntese , Microbiologia de Alimentos , Penicillium/crescimento & desenvolvimento , Triticum/microbiologia , Água/química , Cromatografia em Gel , Cromatografia em Camada Fina , Citrinina/análise , Cinética , Penicillium/metabolismo , Penicillium/efeitos da radiação , Fatores de TempoRESUMO
This is an overview of the most important toxicogenic species of molds that contaminate human food and animal feed. Effects of fungal secondary metabolites are described. Attention is focused on toxicogenic species of Aspergillus, Penicillium and Fusarium. Species of other genera reported as toxicogenic are also considered.
Assuntos
Contaminação de Alimentos , Microbiologia de Alimentos , Fungos/isolamento & purificação , Micotoxinas/isolamento & purificação , Aflatoxinas/efeitos adversos , Aflatoxinas/biossíntese , Aflatoxinas/isolamento & purificação , Doenças dos Animais/induzido quimicamente , Ração Animal/microbiologia , Animais , Aspergillus/classificação , Aspergillus/isolamento & purificação , Aspergillus/metabolismo , Carcinógenos/isolamento & purificação , Carcinógenos/metabolismo , Doenças Transmitidas por Alimentos/etiologia , Doenças Transmitidas por Alimentos/veterinária , Fungos/classificação , Fungos/metabolismo , Fusarium/classificação , Fusarium/isolamento & purificação , Fusarium/metabolismo , Humanos , Estrutura Molecular , Micotoxinas/efeitos adversos , Micotoxinas/biossíntese , Micotoxinas/química , Micotoxinas/classificação , Penicillium/classificação , Penicillium/isolamento & purificação , Penicillium/metabolismo , Segurança , Especificidade da EspécieRESUMO
The influence of water activity (aw) on growth of a xerophilic mold isolated from dried figs and identified as Eurotium herbariorum was studied on culture media of aw adjusted with sucrose or glycerol. Rate of radial growth (kr) and lag period were the kinetic parameters analyzed. Fungal growth was inhibited at aw > 0.97. In the presence of sucrose, optimum growth was found in M6OY agar (malt agar with yeast extract and 60% W/V of sucrose, aw = 0.95). On glycerol (aw ranging from 0.65 to 0.90) the fungus did not grow at aw < 0.80. Sucrose supported better growth than glycerol at aw 0.90.
Assuntos
Ascomicetos/crescimento & desenvolvimento , Microbiologia de Alimentos , Frutas/microbiologia , Água , Ascomicetos/isolamento & purificação , Meios de Cultura/farmacologia , Dessecação , Conservação de Alimentos , Glicerol/farmacologia , Umidade , Sacarose/farmacologia , TemperaturaRESUMO
The influence of water activity (aw) on growth of a xerophilic mold isolated from dried figs and identified as Eurotium herbariorum was studied on culture media of aw adjusted with sucrose or glycerol. Rate of radial growth (kr) and lag period were the kinetic parameters analyzed. Fungal growth was inhibited at aw > 0.97. In the presence of sucrose, optimum growth was found in M6OY agar (malt agar with yeast extract and 60
W/V of sucrose, aw = 0.95). On glycerol (aw ranging from 0.65 to 0.90) the fungus did not grow at aw < 0.80. Sucrose supported better growth than glycerol at aw 0.90.
RESUMO
The influence of water activity (aw) on growth of a xerophilic mold isolated from dried figs and identified as Eurotium herbariorum was studied on culture media of aw adjusted with sucrose or glycerol. Rate of radial growth (kr) and lag period were the kinetic parameters analyzed. Fungal growth was inhibited at aw > 0.97. In the presence of sucrose, optimum growth was found in M6OY agar (malt agar with yeast extract and 60
W/V of sucrose, aw = 0.95). On glycerol (aw ranging from 0.65 to 0.90) the fungus did not grow at aw < 0.80. Sucrose supported better growth than glycerol at aw 0.90.
