EFEITO DOS TRATAMENTOS TÉRMICOS SECO E ÚMIDO NOS NÍVEIS DE AFLATOXINA B1 E OCRATOXINA A PRESENTES EM FARELO E FARINHAS CEREAIS

  The effect of dry and wet thermal treatment was studied on levels of aflatoxin B1 and ochratoxin A contaminating simultaneously defatted rice bran, wholemeal wheat and wholemeal oat, employed in the production of baby food. Each  sample was artificially contaminated with different concentrations of each mycotoxins (3 to 95 ppb) and the thermal treatments  were  carried out in oven at 220ºC and  autoclave (121ºC; 1,1 Pa man) during  5 and 15 minutes. The residual mycotoxins were quantified, after confirmation by chemical derivation, as thin layer multimethod.  The thermal treatments and exposure time decreased the levels of mycotoxins until levels lower than the detection limits in 45 and 64% of the studied condition for aflatoxin B1 and ochratoxin A respectively. The defatted rice bran was best decontaminated by the wet thermal treatment and the wholemeal by dry treatment.Estudou-se o efeito dos tratamentos térmicos seco e úmido sobre os níveis de aflatoxina B1 e ocratoxina A presentes simultaneamente em farelo de arroz desengordurado e farinhas integrais de trigo e aveia, utilizados para a produção de alimentos infantis. Cada amostra foi contaminada com diferentes concentrações de cada micotoxinas, (3 a 95 ppb) e os tratamentos térmicos realizados em estufa a 220ºC e autoclave (121ºC; 1,1 Pa man) durante 5 e 15 minutos. As micotoxinas residuais foram quantificadas, após confirmação por derivação química, conforme o multimétodo de cromatografia em  camada delgada. Os tratamentos térmicos e os tempos de exposição  ocasionaram diminuição nos  níveis das micotoxinas a valores inferiores aos limites de detecção em 45 e 64% das condições estudadas para a aflatoxina B1 e ocratoxina A, respectivamente. O farelo de arroz desengordurado foi mais susceptível à descontaminação pelo calor úmido, enquanto as farinhas pelo calor seco

Otimização de metodologia para derivação de desoxinivalenol através de planejamento experimental.

The objective of this work was to optimize the derivatization reaction for determining deoxynivalenol (DON) by gas chromatography employing an experimental planning procedure. The factors were: temperature, reaction time, catalyst and trifluoroacetic anhydride concentration. The relative peak areas were used to evaluated the effects. The best conditions for DON derivatization were 200 μL TFAA and 18 mg sodium bicarbonate for 6 min at 74 °C for 7 to 21 μg of DON. Under these conditions, the detection limit was 1.4 μg of DON

Kinetics of deoxynivalenol degradation by aspergillus oryzae and rhizopus oryzae in submerged fermentation

O objetivo foi avaliar a capacidade das espécies fúngicas Aspergillus oryzae e Rhizopus oryzae em degradar desoxinivalenol (DON) em fermentação submersa. O meio submerso utilizado foi água destilada estéril contaminada com 1mg mL-1 DON, inoculado com 4 × 106 esporos mL-1 das espécies fúngicas. A amostragem foi realizada a cada 48 h até 240 h de processo, determinando a massa residual de DON, percentual e velocidade de degradação. A massa residual de DON no meio coletado foi extraída por partição líquido-líquido e quantificada por cromatografia gasosa através de derivação com anidrido trifluoroacético. O tempo requerido para a maior degradação de DON foi 96 e 240 h para Aspergillus oryzae e Rhizopus oryzae, respectivamente, e velocidade de degradação de 0,62 e 0,54 mg h-1, respectivamente. Rhizopus oryzae ocasionou a maior diminuição na concentração de DON, aproximadamente 90% em 240 h, enquanto Aspergillus oryzae ocasionou com maior rapidez, 74% de redução em 96 h.The objective was to evaluate the capacity of Aspergillus oryzae and Rhizopus oryzae to degrade deoxynivalenol (DON) during submerged fermentation. The submerged medium utilized was sterile distilled water with 1mg mL-1 DON, added and inoculated with 4 × 106 spores mL-1 of the fungal species. Sampling was performed every 48 h to 240 h. DON analyses included residual mass, percentage and velocity of degradation. Residual mass of DON in the collected medium was extracted by liquid-liquid partition and quantified by gas chromatography through derivation with trifluoroacetic anhydride. The time required for the largest DON degradation was 96 h and 240 h by Aspergillus oryzae and Rhizopus oryzae respectively, and degradation rate were 0.62 and 0.54 mg h-1, respectively. Rhizopus oryzae caused the largest decrease in DON at around 90% in 240 h, while Aspergillus oryzae caused the most rapid degradation with a 74% reduction of DON at 96 h

Degradação de deoxinivalenol (DON) e a atividade da enzima peroxidase durante fermentação submersa.

Submitted by Fabiane Ribas ([email protected]) on 2012-01-14T19:17:03Z No. of bitstreams: 1 DEOXYNIVALENOL (DON) DEGRADATION AND PEROXIDASE ENZYME ACTIVITY IN A SUBMERGED FERMENTATION.pdf: 681705 bytes, checksum: 87d6e39f24429d508dd546a8f775482a (MD5)Approved for entry into archive by Barbara Milbrath([email protected]) on 2012-03-06T04:09:07Z (GMT) No. of bitstreams: 1 DEOXYNIVALENOL (DON) DEGRADATION AND PEROXIDASE ENZYME ACTIVITY IN A SUBMERGED FERMENTATION.pdf: 681705 bytes, checksum: 87d6e39f24429d508dd546a8f775482a (MD5)Made available in DSpace on 2012-03-06T04:09:07Z (GMT). No. of bitstreams: 1 DEOXYNIVALENOL (DON) DEGRADATION AND PEROXIDASE ENZYME ACTIVITY IN A SUBMERGED FERMENTATION.pdf: 681705 bytes, checksum: 87d6e39f24429d508dd546a8f775482a (MD5) Previous issue date: 2011This work aims to evaluate deoxynivalenol degradation by Aspergillus oryzae and Rhizopus oryzae in a submerged fermentation system and to correlate it to the activity of oxydo-reductase enzymes. The submerged medium consisted of sterile distilled water contaminated with 50 μg of DON and 4 × 106 spore.mL–1 inoculum of Aspergillus oryzae and Rhizopus oryzae species, respectively in each experiment. Sampling was performed every 24 hours for monitoring the peroxidase specific activity, and every 48 hours for determining mycotoxin levels. Results showed that the fungi species were able to decrease DON levels as the peroxidase activity increased. The 48 hours fermentation interval presented the highest peroxidase specific activity (ΔABS/minute.μg.protein–1), 800 and 198, while the highest DON degradation velocity was 10.8 and 12.4 ppb/hour, respectively in both cases for Rhizopus oryzae and Aspergillus oryzae.Este trabalho teve por objetivo avaliar a degradação de deoxinivalenol por Aspergillus oryzae e Rhizopus oryzae durante fermentação submersa e correlacioná-la com a atividade de enzimas oxidoredutases. O meio submerso foi constituído por água destilada estéril contaminada com 50 μg de DON e inóculo de 4 × 106 esporos.mL-1 de meio das espécies fúngicas Aspergillus oryzae e Rhizopus oryzae, separadamente em cada experimento. A amostragem foi realizada a cada 24 horas de processo para medida da atividade específica da enzima peroxidase, e a cada 48 horas para a determinação dos níveis de DON. Os resultados mostraram que as espécies fúngicas avaliadas possuem capacidade de metabolizar DON, acompanhada de aumento na atividade da enzima oxidativa PO. No intervalo de 48 horas de fermentação, ocorreu a maior atividade específica da enzima peroxidase (ΔABS/minute.μg.protein-1), 800 e 198, correspondendo a maior velocidade de degradação de DON de 10.8 e 12.4 ppb/hour, respectivamente para Rhizopus oryzae e Aspergillus oryzae

Deoxynivalenol (DON) degradation and peroxidase enzyme activity in submerged fermentation

This work aims to evaluate deoxynivalenol degradation by Aspergillus oryzae and Rhizopus oryzae in a submerged fermentation system and to correlate it to the activity of oxydo-reductase enzymes. The submerged medium consisted of sterile distilled water contaminated with 50 μg of DON and 4 × 106 spore.mL–1 inoculum of Aspergillus oryzae and Rhizopus oryzae species, respectively in each experiment. Sampling was performed every 24 hours for monitoring the peroxidase specific activity, and every 48 hours for determining mycotoxin levels. Results showed that the fungi species were able to decrease DON levels as the peroxidase activity increased. The 48 hours fermentation interval presented the highest peroxidase specific activity (ΔABS/minute.μg.protein–1), 800 and 198, while the highest DON degradation velocity was 10.8 and 12.4 ppb/hour, respectively in both cases for Rhizopus oryzae and Aspergillus oryzae.Este trabalho teve por objetivo avaliar a degradação de deoxinivalenol por Aspergillus oryzae e Rhizopus oryzae durante fermentação submersa e correlacioná-la com a atividade de enzimas oxidoredutases. O meio submerso foi constituído por água destilada estéril contaminada com 50 μg de DON e inóculo de 4 × 106 esporos.mL-1 de meio das espécies fúngicas Aspergillus oryzae e Rhizopus oryzae, separadamente em cada experimento. A amostragem foi realizada a cada 24 horas de processo para medida da atividade específica da enzima peroxidase, e a cada 48 horas para a determinação dos níveis de DON. Os resultados mostraram que as espécies fúngicas avaliadas possuem capacidade de metabolizar DON, acompanhada de aumento na atividade da enzima oxidativa PO. No intervalo de 48 horas de fermentação, ocorreu a maior atividade específica da enzima peroxidase (ΔABS/minute.μg.protein-1), 800 e 198, correspondendo a maior velocidade de degradação de DON de 10.8 e 12.4 ppb/hour, respectivamente para Rhizopus oryzae e Aspergillus oryzae

Effect of Deoxynivalenol and T-2 Toxin in Malt Amylase Activity

The objective of this work was to evaluate the effect of DON and T-2 toxin levels on the malt amylase activity. The malt was contaminated in accordance with central composite design experiment with DON and T-2 toxin levels until 1000 ng/g. The activities of the enzymes were evaluated by Bernfeld method. The increase in T-2 toxin concentration inhibited the a-amylase activity. However, the increase of both toxins concentration caused inverse effect. The interaction between toxins indicated synergetic effect on the b-amylase activity. An increased activity occurred when the toxins contamination levels in malt were higher (1000ng/g malt). The trichothecenes interfered with the performance of aminolitic enzymes in the stage of malting, resulting in a significant model for enzymatic activity of b-amylase

Determinação de tricotecenos em cerveja e avaliação de incidência no produto comercializado no Rio Grande do Sul

Este trabalho adaptou um método e avaliou os seus indicadores de mérito para determinação de tricotecenos, desoxinivalenol (DON)e toxina T-2, em cervejas comercializadas na região Sul do Rio Grande do Sul, empregando cromatografia gasosa. As adaptações foram realizadas na etapa de extração,purificação, derivação e condições cromatográficas usando amostras de cerveja artificialmente contaminadas,avaliando a adequação do procedimento pela recuperação obtida. Foram estudados os solventes acetonitrila, metanol e cloreto de metileno puro ou em misturas para a etapa de extração. A purificação do extrato foi realizada empregando ou não minicoluna de carvão:alumina:celite (7:5:3). Para a derivação testou-se basicidade do meio (bicarbonato de sódio, piridina), agente acilante (TFAA e HFBI), tempo (30 e 60 minutos) e temperatura (60 e 80ºC). Foram otimizadas as condições cromatográficas em cromatógrafo gasoso equipado com injetor split/splitless e detector de ionização de chama. A melhor recuperação foi obtida quando se empregou partição líquido-líquido com cloreto de metileno, seguida da limpeza em minicoluna e derivação com TFAA e piridina a 60°C durante 60 minutos.A recuperação média foi de 83 e 103% para DON e toxina T-2 respectivamente, para níveis de adição entre 50 e 200ng/mL. O coeficiente de variação assumiu valores de 2% e 4% e limite de detecção de 21 e 60 ng/mL. A aplicabilidade do método foi testada em um levantamento realizado em 72 amostras de cervejas. Destas 9,7% estavam contaminadas, sendo 5,3% com DON (50 a 336ng/mL)e 4,5% com toxina T-2 (114 a 249ng/mL).The present work adapted and evaluated a trichothecenes determination, DON and the T-2 toxin and conduted a survey of the product commercialized in Rio Grande do Sul in beer commercialized in Rio Grande do Sul State by gas chromatography.It studied extraction, purification, derivatization and chromatographic conditions using artificially contaminated samples. Acetonitrile,methylene chloride and methanol pure or in misture were tested for the extraction step. The extract was purified using a carbon:alumina:celite minicolumn (7:5:3). For derivatization, the following conditions were tested: the basicity of the medium (sodioum bicarbonate, pyridine),the derivatizing agent (TFAA and HFBI), reaction time (30 and 60 minutes) and temperature (60 and 80°C). The chromatographic conditions were optimized in a gas chromatograph, with a split/splitless injector and an ionization flame detector.The highest recovery was obtained when liquid-liquid partition was carried out with methylene chloride,followed by cleaning in a minicolumn and derivatization with TFAA and pyridine at a temperature of 60°C for 60 minutes. The average recovery for DON and the T-2 toxin were 83 and 103%, the coefficient variation 1.6 to 4% and the detection limit of 21 and 60ng/mL, respectively. The applicability of the method was tested in a survey carried out in 72 beer samples, 9.7 % of which were contaminated 5.3% with DON (50 to 336ng/mL) and 4.5% with the T-2 toxin (114 to 49ng/mL)

Deoxynivalenol and nivalenol in commercial wheat grain related to Fusarium head blight epidemics in southern Brazil

Submitted by Vitor de Carvalho ([email protected]) on 2014-11-07T18:32:57Z No. of bitstreams: 1 Deoxynivalenol and nivalenol in commercial wheat grain related to Fusarium head blight epidemics in southern Brazil.pdf: 468001 bytes, checksum: 78177f70571149a736d3deae504ef5ce (MD5)Approved for entry into archive by Paula Gautério ([email protected]) on 2014-11-22T22:27:37Z (GMT) No. of bitstreams: 1 Deoxynivalenol and nivalenol in commercial wheat grain related to Fusarium head blight epidemics in southern Brazil.pdf: 468001 bytes, checksum: 78177f70571149a736d3deae504ef5ce (MD5)Made available in DSpace on 2014-11-22T22:27:37Z (GMT). No. of bitstreams: 1 Deoxynivalenol and nivalenol in commercial wheat grain related to Fusarium head blight epidemics in southern Brazil.pdf: 468001 bytes, checksum: 78177f70571149a736d3deae504ef5ce (MD5) Previous issue date: 2012A three-year (2006–2008) survey on commercial wheat grain was conducted aimed at quantifying the intensity of Fusarium head blight epidemics related to kernel quality and levels of deoxynivalenol (DON) and nivalenol (NIV). Grain samples, obtained from 38 municipalities throughout the state of Rio Grande do Sul, Brazil, were assessed visually for Fusarium-damaged kernels (FDK) and chemically using liquid chromatography–mass spectrometry (LC–MS/MS). Overall FDK mean levels were 15.5%, not differing among the years. Co-contamination was predominant (59/66) across samples and overall mean levels of DON and NIV were 540 and 337 lg/kg, respectively. When the levels of both mycotoxins were added together (DON + NIV), a higher correlation with FDK was found (R = 0.36, P < 0.01), compared to single toxin data. For the first time, the presence of NIV in levels comparable to DON is reported from a multi-year regional epidemiological survey in the country which should be of concern to the small grains industry