Thesis--Wisconsin. / Includes bibliographical references (leaves 72-79).

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The combined effect of Modified Atmosphere Packaging (MAP) involving gas packaging, oxygen absorbent and other environmental factors to control aflatoxin production by Aspergillus flavus and Aspergillus parasiticus in both synthetic media and peanuts were studied using a process optimization technique termed Response Surface Methodology (RSM). Regression analysis of the data indicated that water activity (a$ sb{ rm w}$), pH, storage temperature, initial concentration of headspace oxygen and inoculum level were all highly significant factors (p 0%). These changes in the barrier characteristics influenced the headspace gas composition within the product and under modified atmospheres hence the level of aflatoxin detected in these stored products. / In conclusion, this study has shown that the combined effect of several "barriers" can be used in conjunction with low oxygen modified atmosphere and high barrier packaging films to inhibit or reduce aflatoxin to safe and acceptable levels, particularly at abusive temperatures encountered during storage.

Com o Avanço na área da biotecnologia, principalmente relacionadas à tecnologia das fermentações, almejam pespectivas para o biotratamento de resíduos. O termo resíduo é utilizado em sentido amplo, juntando não somente sólidos mais também os efluentes líquidos e os materiais presentes nas emissões atmosféricas. Os efluentes industriais gerados em indústrias de laticínios que em geral possuem elevados teores de demanda bioquímica (DBO) e química de oxigênio (DQO), tendo em vista um elevado conteúdo de gorduras, aumentam a concentração de matéria orgânica, Justificando a necessidade de biotratamento. Neste sentido foram avaliados o potencial biotecnológico do fungo Aspergillus parasiticus isolado do solo da Caatinga, PE, Brasil, na produção de biomoléculas de enzima lipase e lípídeos, visando à aplicação no biotratamento de resíduos da indústria de laticíneos. A confirmação da produção da enzima por A. parasiticus foi realizada com o cultivo em meio padrão na presença do óleo de oliva 0,5 g/L durante 120 h, incubados a 28C e 37C, respectivamente. Os resultados obtidos demonstraram que a melhor condição foi obtida em 96 h de cultivo a 28C com um ídice de 5,2 U/ml. Em seguida foram realizados ensaios com resíduos ricos em óleos, o soro de leite (SL) e o resíduo de sorvete (RS), provenientes de rejeitos das indústrias lácteas, utilizando um planejamento fatorial 22, com três repetições no ponto central, durante 120 horas a 28C. Observam-se que o ensaio 4, com 45% de (RS) e 30% (SL) demonstravam os melhores resultados na produção de biomassa 68,1 g/L e atividade lipolítica 20,0 U/mL, e um maior acumulo de lipídeos em sua biomassa atingindo 67.61 %, sugerindo que o biotratamento é possível, além de outras aplicabilidades na biotecnologia em especial a produção de biodiesel, se tratando de um fungo oleaginoso. / With the advance in biotechnology, especially related to technology of fermentation, aumejam pespectivas for bioremediation of waste. The term waste is used in a broad sense, adding not only more solid also the wastewater and the materials present in air emissions. The waste water generated in general that dairy industries have high levels of biochemical demand (BOD) and chemical oxygen (COD) with a view to a high content of fats, increase the concentration of organic matter, justifying the need to bioprocessing. In this sense we assessed the biotechnological potential of the fungus Aspergillus parasiticus isolated from soil of the Caatinga, PE, Brazil, in the production of biomolecules lipase enzyme and lipid seeking their application in bioremediation of waste from laticíneos industry. Confirmation of enzyme production by Aspergillus parasiticus was performed by culturing in standard medium in the presence of olive oil 0.5 g / L for 120 h, incubated at 28 C and 37 C respectively. The results showed that the best condition was obtained in 96 hours of cultivation at 28 C with a Idice 5.2 U / ml. Then tests were carried out with waste rich in oils, serum leiten (SL) and the ice cream residue (RS) from the dairy industry waste, using a 22 factorial design with three replications at the center point, for 120 hours at 28 C. Observed that the test 4, with 45% (RS) and 30% (SL) showed the best results in the production of biomass 68.1 g / L and lipase activity 20.0 U / mL, and greater accumulation of lipids in their biomass reaching 67.61% in lipids, suggesting that the biotreatment is possible, in addition to other applicability in biotechnology in particular the production of biodiesel, in the case of an oleaginous fungus.

<p>Aflatoxins (AFs) are highly toxic second metabolites produced by <i>Aspergillus flavus </i>and<i> A. parasiticus</i>. They are widely detected in cereals, spices, and drinks worldwide. Aflatoxin contamination of foods and crops poses a high health risk for humans and livestock. It is well known that environmental conditions and substrates could influence fungal growth and aflatoxin production. This study tested the effect of water activity (0.82, 0.86, 0.90, 0.94, and 0.98 a_w) and incubation temperatures (20°, 27°, and 35°C) on the growth and aflatoxin production of <i>A. flavus </i>and <i>A. parasiticus</i> on ground flax seeds and ground niger seeds. The effect of oil contents of ground niger seeds on fungal growth and aflatoxin production was also investigated in this study.</p><p> These two fungal species could not grow on any of the tested substrates with 0.82 a_w at 20°, 27°, or 35°C. <i>Aspergillus flavus</i> grew most rapidly on flax seeds with 0.90 a_w at 27°C and also 0.94 a_w at 27° or 35°C. However, on niger seeds, <i>A. flavus </i>grew best at 0.90 or 0.94 a_w incubated at 35°C as well as at 0.94 or 0.98 a_w incubated at 27°C. <i>Aspergillus parasiticus</i> showed the optimum growth on flax seeds with 0.90 a_w at 35°C, whereas on niger seeds, the optimum occurred on seeds with 0.90 a_w at 35°C and also on seeds with 0.94 a_w at 27° or 35°C. The optimum conditions for <i>A. flavus </i>to produce high levels of aflatoxins (270-299 μg/kg) on flax seeds were 0.90 a_w at 35°C; whereas, the optimum conditions for <i>A. flavus </i>to produce aflatoxin (203-278 μg/kg) on niger seeds were 0.90 or 0.98 a_w at 27°C and also 0.90 a_w at 35°C. <i>Aspergillus parasiticus</i> produced high levels of aflatoxins (284-365 μg/kg) on flax seeds under the following three conditions, 0.86 or 0.98 a_w at 35°C and 0.94 a_w at 27°C; <i>A. parasiticus</i> produced 200-384 μg/kg of aflatoxins on niger seeds under nine out of 12 tested incubation conditions.</p><p> Reducing mean oil contents from 35.2 to 10.5% of ground niger seeds had very little effect on the growth of the two fungi but significantly decreased their aflatoxin production under certain incubation conditions. On de-oiled niger seeds inoculated with <i>A. flavus</i>, only 13μg/kg of AFB1 was found on seeds with 0.94 a_w at 27°C; whereas, on de-oiled niger seeds inoculated with <i>A. parasiticus</i>, high levels of aflatoxins (245-345 μg/kg) were only detected under the three following incubation conditions, 0.90 or 0.94 a_w at 27°C, and 0.86 a_w at 35°C.</p> This study showed that the optimum growth and aflatoxin production by <i>A. flavus </i>and<i> A. parasiticus </i>were not identical and influenced by incubation conditions, including temperature, water activity, and growth substrates. The results of this study could help establish guidelines for post-harvest and storage conditions for oil seeds to prevent fungal growth and aflatoxin formation.

Made available in DSpace on 2017-06-01T18:20:45Z (GMT). No. of bitstreams: 1 roberta_leite_santos_reis.pdf: 1050930 bytes, checksum: b8b3fa607a305cc7525e614247e5febb (MD5) Previous issue date: 2015-02-23 / With the advance in biotechnology, especially related to technology of fermentation, aumejam pespectivas for bioremediation of waste. The term waste is used in a broad sense, adding not only more solid also the wastewater and the materials present in air emissions. The waste water generated in general that dairy industries have high levels of biochemical demand (BOD) and chemical oxygen (COD) with a view to a high content of fats, increase the concentration of organic matter, justifying the need to bioprocessing. In this sense we assessed the biotechnological potential of the fungus Aspergillus parasiticus isolated from soil of the Caatinga, PE, Brazil, in the production of biomolecules lipase enzyme and lipid seeking their application in bioremediation of waste from laticíneos industry. Confirmation of enzyme production by Aspergillus parasiticus was performed by culturing in standard medium in the presence of olive oil 0.5 g / L for 120 h, incubated at 28 ° C and 37 ° C respectively. The results showed that the best condition was obtained in 96 hours of cultivation at 28 ° C with a Idice 5.2 U / ml. Then tests were carried out with waste rich in oils, serum leiten (SL) and the ice cream residue (RS) from the dairy industry waste, using a 22 factorial design with three replications at the center point, for 120 hours at 28 ° C. Observed that the test 4, with 45% (RS) and 30% (SL) showed the best results in the production of biomass 68.1 g / L and lipase activity 20.0 U / mL, and greater accumulation of lipids in their biomass reaching 67.61% in lipids, suggesting that the biotreatment is possible, in addition to other applicability in biotechnology in particular the production of biodiesel, in the case of an oleaginous fungus. / Com o Avanço na área da biotecnologia, principalmente relacionadas à tecnologia das fermentações, almejam pespectivas para o biotratamento de resíduos. O termo resíduo é utilizado em sentido amplo, juntando não somente sólidos mais também os efluentes líquidos e os materiais presentes nas emissões atmosféricas. Os efluentes industriais gerados em indústrias de laticínios que em geral possuem elevados teores de demanda bioquímica (DBO) e química de oxigênio (DQO), tendo em vista um elevado conteúdo de gorduras, aumentam a concentração de matéria orgânica, Justificando a necessidade de biotratamento. Neste sentido foram avaliados o potencial biotecnológico do fungo Aspergillus parasiticus isolado do solo da Caatinga, PE, Brasil, na produção de biomoléculas de enzima lipase e lípídeos, visando à aplicação no biotratamento de resíduos da indústria de laticíneos. A confirmação da produção da enzima por A. parasiticus foi realizada com o cultivo em meio padrão na presença do óleo de oliva 0,5 g/L durante 120 h, incubados a 28°C e 37ºC, respectivamente. Os resultados obtidos demonstraram que a melhor condição foi obtida em 96 h de cultivo a 28°C com um ídice de 5,2 U/ml. Em seguida foram realizados ensaios com resíduos ricos em óleos, o soro de leite (SL) e o resíduo de sorvete (RS), provenientes de rejeitos das indústrias lácteas, utilizando um planejamento fatorial 22, com três repetições no ponto central, durante 120 horas a 28°C. Observam-se que o ensaio 4, com 45% de (RS) e 30% (SL) demonstravam os melhores resultados na produção de biomassa 68,1 g/L e atividade lipolítica 20,0 U/mL, e um maior acumulo de lipídeos em sua biomassa atingindo 67.61 %, sugerindo que o biotratamento é possível, além de outras aplicabilidades na biotecnologia em especial a produção de biodiesel, se tratando de um fungo oleaginoso.