Abstract A Plackett–Burman Factorial Design of 16 experiments was conducted to assess the influence of nine factors on the production of lipases by filamentous fungi. The factors investigated were bran type (used as the main carbon source), nitrogen source, nitrogen source concentration, inducer, inducer concentration, fungal strain (Aspergillus niger or Aspergillus flavus were selected as good lipase producers via submerged fermentation), pH and agitation. The concentration of the yeast extract and soybean oil and the pH had a significant effect (p < 0.05) on lipase production and were consecutively studied through a Full Factorial Design 23, with the concentration of yeast extract and pH being significant (p < 0.05). These variables were optimized using a central composite design, obtaining maximum lipolytic activities with the use of 45 g/L of yeast extract and pH 7.15. The statistical model showed a 94.12% correlation with the experimental data.

Filamentous fungi were cultured under solid state fermentation of soybean residues to produce lipases. Enzymes produced by Aspergillus niger esterified oleic and butyric acids in the presence of ethanol, while enzymes produced by Aspergillus fumigatus demonstrated no esterification activity toward lauric acid. In case of A. niger, direct lyophilization of fermented bran led to higher esterification activity. The esterification of oleic acid by enzymes of A. fumigatus was neither influenced by pH adjustment nor by the extraction process. Conversions to ethyl esters were higher after pH adjustment with lyophilized liquid extract of A. niger.

Objetivou-se avaliar o potencial de sacarificação do malte de milho para produção de álcool deste cereal. Para tal, foi realizada germinação do grão de milho a 20 ºC por 5 dias. O potencial amilolítico do malte de milho foi otimizado por meio de um Planejamento Fatorial Completo 2² com 3 pontos centrais, sendo as variáveis de estudo a temperatura de incubação e concentração de substrato [S]. A sacarificação foi realizada por meio de um Planejamento de Mistura com três pontos centrais, sendo as variáveis de estudo a concentração de malte e concentração de substrato, durante 6 horas. A fermentação foi conduzida com a melhor condição de sacarificação, em reator de 5 L e volume útil de 2 L. O pH foi fixado em 4,5-5. O Brix foi acertado para o valor de 14º. O mosto hidrolisado foi esterilizado e inoculado com 5,0 g.L-1 de Saccharomyces cerevisiae proveniente de fermento comercial liofilizado. O sistema foi submetido a 2 horas de aeração inicial (170 L O2.h-1) e mantido na temperatura de 30 ºC. Durante o processo de fermentação, foram realizadas determinações da concentração de células (g.L-1), açúcares redutores (mg.mL-1) e álcool (g.L-1). As variáveis temperatura de incubação e concentração de substrato foram significativos (p< 0,05) na condição de estudo de 20 % de substrato e incubação a 70 ºC. Os experimentos centrais com 50 % de malte apresentaram os melhores parâmetros cinéticos com taxa volumétrica de formação de produto em etanol de 2,81 g etanol.L-1.h-1 que corresponde a 8,0 ºGL e conversão de substrato em células 0,127 g célula.g glicose-1 .

The aim of this research was the production of maize malt and the evaluation of its use for alcohol production. The maize grain was allowed to germinate at 20ºC for five days. The amylolitic potential of malt was optimized through a Complete Factorial Planning 2² with three central points, where the study variables were the temperature of incubation and the substrate concentration [S]. The sacarification was performed through a Planning of Mixture with three central points, where the study variables were the malt concentration and [S] during six 6 hours. The fermentation was carried out using the best sacarification condition, in a five-liter reactor and a two-liter working volume. The pH was maintained at 4.5 - 5.0. The Brix was corrected to 14º. The sterile hydrolyzed product was inoculated with 5.0 g.L-1 Saccharomyces cerevisiae. The system was submitted to two hours of initial aeration (170 L O2.h-1) and kept at 30ºC. During the fermentation process, analyses were made to determine the cell concentrations (g.L-1), reducing sugars (mg.mL-1), alcohol (g.L-1) and ºBrix. The temperature of incubation and substrate concentration were significant factors (p<0.05) in the determination of the amylolytic potential under the conditions of study utilizing 20% of substrate and incubation at 70ºC. The central experiments with 50% malt presented the best kinetic parameters with a volumetric rate of ethanol formation of 2.81 g ethanol.L-1.h-1, which correspond to 8.0 ºGL, and a substrate conversion in cells of 0.127g cells.g glucose-1 .

Os tricotecenos são metabólitos produzidos por diversos fungos, principalmente os do gênero Fusarium. As condições climáticas de diversos países, como o Brasil, favorecem o crescimento desses fungos e a produção dos tricotecenos, os quais podem estar presentes em vários cereais, como por exemplo a cevada, que pode ser utilizada em processos fermentativos visando a obtenção de álcool. Com o objetivo de estudar a influência que essas micotoxinas apresentam na produção de álcoois, um processo fermentativo em pequena escala foi simulado. Malte foi contaminado com deoxinivalenol e toxina T-2 em diferentes quantidades (até 500 ppb), de acordo com um planejamento fatorial 3², e os álcoois obtidos após a fermentação foram determinados por cromatografia gasosa. Os resultados mostraram que os tricotecenos podem influenciar o perfil dos álcoois produzidos pela levedura Saccharomyces cerevisiae durante o processo fermentativo do malte, especialmente dos álcoois metílico e isoamílico.

In order to study the influence of mycotoxins on the production of alcohols, a fermentative process on a laboratorial scale was simulated. Malt was contaminated with deoxynivalenol and T-2 in different ratios (up to 500 ppb), according to a 3² factorial design, and the alcohols obtained after the fermentation were determined through gas chromatography. The results showed that trichothecenes influenced the profile of the alcohols produced by Saccharomyces cerevisiae during the fermentative process of malt, especially the profile of methyl and isoamyl alcohols.