Débora A. Oliveira - Academia.edu (original) (raw)
Papers by Débora A. Oliveira
Journal of Food Engineering, 2009
Journal of Supercritical Fluids, 2005
Applied Biochemistry and Biotechnology, 2004
The production of lipases by Penicillium simplicissimum using solid-state fermentation and soy ca... more The production of lipases by Penicillium simplicissimum using solid-state fermentation and soy cake as substrate was investigated. The effects of temperature, cake moisture, and carbon supplementation on lipase production were studied using a two-level experimental plan. Moisture, pH, and lipase activity were followed during fermentation. Statistical analysis of the results was performed to evaluate the effect of the studied variables on the maximum lipase activity. Incubation temperature was the variable that most affected enzyme activity, showing a negative effect. Moisture and carbon supplementation presented a positive effect on activity. It was possible to obtain lipase activity as high as 21 U/g of dry cake in the studied range of process variables.
Applied Biochemistry and Biotechnology, 2004
We studied the production of fatty acid ethyl esters from castor oil using n-hexane as solvent an... more We studied the production of fatty acid ethyl esters from castor oil using n-hexane as solvent and two commercial lipases, Novozym 435 and Lipozyme IM, as catalysts. For this purpose, a Taguchi experimental design was adopted considering the following variables: temperature (35–65°C), water (0–10 wt/wt%), and enzyme (5–20 wt/wt%) concentrations and oil-to-ethanol molar ratio (1∶3 to 1∶10). An empirical model was then built so as to assess the main and cross-variable effects on the reaction conversion and also to maximize biodiesel production for each enzyme. For the system containing Novozym 435 as tatalyst the maximum conversion obtained was 81.4% at 65°C, enzyme concentration of 20 wt/wt%, water concentration of 0 wt/wt%, and oil-to-ethanol molar ratio of 1∶10. When the catalyst was Lipozyme IM, a conversion as high as 98% was obtained at 65°C, enzyme concentration of 20 wt/wt%, water concentration of 0 wt/wt%, and oil-to-ethanol molar ratio of 1∶3.
Journal of Supercritical Fluids, 2008
Journal of Supercritical Fluids, 2001
... Also, to the best of our knowledge, there is no comprehensive study available comparing conve... more ... Also, to the best of our knowledge, there is no comprehensive study available comparing conventional and supercritical media for this reaction. ... For this purpose, a Taguchi experimentaldesign with two levels and four variables was adopted for each system to allow the ...
Journal of Supercritical Fluids, 2006
Applied Biochemistry and Biotechnology, 2006
Inulinase is an enzyme relevant to fructose production by enzymatic hydrolysis of inulin. This en... more Inulinase is an enzyme relevant to fructose production by enzymatic hydrolysis of inulin. This enzyme is also applied in the production of fructo-oligosaccharides that may be used as a new food functional ingredient. Commercial inulinase is currently obtained using inulin as substrate, which is a relatively expensive raw material. In Brazil, the production of this enzyme using residues of sugarcane and corn industry (sugarcane bagasse, molasses, and corn steep liquor) is economically attractive, owing to the high amount and low cost of such residues. In this context, the aim of this work was the assessment of inulinase production by solid state fermentation using by Kluyveromyces marxianus NRRL Y-7571. The solid medium consisted of sugar cane bagasse supplemented with molasses and corn steep liquor. The production of inulinase was carried out using experimental design technique. The effect of temperature, moisture, and supplements content were investigated. The enzymatic activity reached a maximum of 445 units of inulinase per gram of dry substrate.
Bioresource Technology, 2009
Journal of Supercritical Fluids, 2008
... Accordingly, these facts may explain the little influence of pressure on the reaction convers... more ... Accordingly, these facts may explain the little influence of pressure on the reaction conversion. ... This result may be of technological importance, as a relatively small amount of solvent seems to be sufficient for conducting enzymatic production of biodiesel, with clear advantage ...
Applied Biochemistry and Biotechnology, 2005
This article reports experimental data on the production of fatty acid ethyl esters from refined ... more This article reports experimental data on the production of fatty acid ethyl esters from refined and degummed soybean oil and castor oil using NaOH as catalyst. The variables investigated were temperature (30–70°C), reaction time (1–3 h), catalyst concentration (0.5–1.5 w/wt%), and oil-to-ethanol molar ratio (1:3–1:9). The effects of process variables on the reaction conversion as well as the optimum experimental conditions are presented. The results show that conversions >95% were achieved for all systems investigated. In general, an increase in reaction temperature, reaction time, and in oil-to-ethanol molar ratio led to an enhancement in reaction conversion, whereas an opposite trend was verified with respect to catalyst concentration.
Journal of Chemical Technology and Biotechnology, 2008
BACKGROUND: Lipase production by Penicillium simplicissimum using soybean meal as substrate has b... more BACKGROUND: Lipase production by Penicillium simplicissimum using soybean meal as substrate has been investigated. A factorial design technique was used to evaluate the effects of incubation temperature, initial moisture of the meal and substrate supplementation with low cost supplements, on lipase production. Soybean oil and wastewater from a slaughterhouse, which is rich on oil and fat, corn steep liquor and yeast hydrolysate, were tested as supplementary carbon and nitrogen sources.RESULTS Cultivation conditions were optimized for the production of lipase by factorial design and response surface methodology. Results show that the microorganism produces very low protease activity (0.21 U gds−1 dry substrate), which helps to maximize lipase production. Soybean meal without supplements appears to be the best medium of those tested for lipase production by P. simplicissimum.CONCLUSION: This work showed that temperature and moisture are the factors that most strongly influence lipase production by P. simplicissimum using soybean meal as substrate. The growth conditions that optimize lipase production are 27.5 °C using substrate with 550 g kg−1 of initial moisture. In optimum conditions lipase activity of 30 U gds−1 dry substrate was obtained. Copyright © 2007 Society of Chemical Industry
Journal of Molecular Catalysis B-enzymatic, 2006
This work investigated the influence of temperature, pressure, exposure times and depressurizatio... more This work investigated the influence of temperature, pressure, exposure times and depressurization rate on the activity of a non-commercial immobilized lipase from Yarrowia lipolytica (YLL) submitted to compressed carbon dioxide, propane and n-butane. A high-pressure cell was employed in the experiments, in the pressure range of 10–280bar, varying the temperature from 35 to 75°C, exposure times from 1 to 6h,
Industrial & Engineering Chemistry Research, 2000
Journal of Supercritical Fluids, 2006
Journal of Food Engineering, 2009
Ciencia E Tecnologia De Alimentos, 2002
A erva-mate é uma matéria-prima de grande importância para a região Sul do Brasil, sendo que a pr... more A erva-mate é uma matéria-prima de grande importância para a região Sul do Brasil, sendo que a produção anual é de aproximadamente 650.000 toneladas de folhas. Atualmente, problemas com o excesso de oferta têm incentivado pesquisadores e empresários a buscar alternativas para a utilização da erva-mate como matéria-prima para o desenvolvimento de novos produtos bem como promover melhorias no processamento industrial visando a obtenção de características organolépticas desejáveis. Neste sentido, o presente trabalho teve por objetivo realizar a caracterização físico-química da erva-mate em função das etapas do processamento industrial (sapeco, secagem e tempo de cancheamento) e verificar como estas etapas influem nos teores de cinzas, fibras, gorduras, proteínas, glicose, sacarose e cafeína presentes na matéria-prima. Os resultados obtidos permitiram verificar que as etapas do processamento industrial influem diretamente nos teores dos compostos citados, mostrando a relevância em se analisar estes resultados quando o objetivo é utilizar esta matéria-prima para o desenvolvimento de novos produtos alimentícios que podem exigir características específicas.
Journal of Supercritical Fluids, 2005
Applied Biochemistry and Biotechnology, 2004
The production of lipases by Penicillium simplicissimum using solid-state fermentation and soy ca... more The production of lipases by Penicillium simplicissimum using solid-state fermentation and soy cake as substrate was investigated. The effects of temperature, cake moisture, and carbon supplementation on lipase production were studied using a two-level experimental plan. Moisture, pH, and lipase activity were followed during fermentation. Statistical analysis of the results was performed to evaluate the effect of the studied variables on the maximum lipase activity. Incubation temperature was the variable that most affected enzyme activity, showing a negative effect. Moisture and carbon supplementation presented a positive effect on activity. It was possible to obtain lipase activity as high as 21 U/g of dry cake in the studied range of process variables.
Bioprocess and Biosystems Engineering, 2008
Current studies about lipase production by solid-state fermentation involve the use of agro-indus... more Current studies about lipase production by solid-state fermentation involve the use of agro-industrial residues towards developing cost-effective systems directed to large-scale commercialization of enzyme-catalyzed processes. In this work, lipase production and partial characterization of the crude enzymatic extracts obtained by Penicillium verrucosum using soybean bran as substrate was investigated. Different inductors were evaluated and the results showed that there is no influence of this variable on the lipase production, while temperature and initial moisture were the main factors that affected enzyme production. The optimized cultivation temperature (27.5 °C) and initial moisture of substrate (55%) were determined using the response surface methodology. Kinetics of lipase production was followed at the optimized growth conditions. Optimum lipase yield was 40 U/g of dry bran. The crude enzymatic extract showed optimal activity in the range from 30 to 45 °C and in pH 7.0.
Journal of Food Engineering, 2009
Journal of Supercritical Fluids, 2005
Applied Biochemistry and Biotechnology, 2004
The production of lipases by Penicillium simplicissimum using solid-state fermentation and soy ca... more The production of lipases by Penicillium simplicissimum using solid-state fermentation and soy cake as substrate was investigated. The effects of temperature, cake moisture, and carbon supplementation on lipase production were studied using a two-level experimental plan. Moisture, pH, and lipase activity were followed during fermentation. Statistical analysis of the results was performed to evaluate the effect of the studied variables on the maximum lipase activity. Incubation temperature was the variable that most affected enzyme activity, showing a negative effect. Moisture and carbon supplementation presented a positive effect on activity. It was possible to obtain lipase activity as high as 21 U/g of dry cake in the studied range of process variables.
Applied Biochemistry and Biotechnology, 2004
We studied the production of fatty acid ethyl esters from castor oil using n-hexane as solvent an... more We studied the production of fatty acid ethyl esters from castor oil using n-hexane as solvent and two commercial lipases, Novozym 435 and Lipozyme IM, as catalysts. For this purpose, a Taguchi experimental design was adopted considering the following variables: temperature (35–65°C), water (0–10 wt/wt%), and enzyme (5–20 wt/wt%) concentrations and oil-to-ethanol molar ratio (1∶3 to 1∶10). An empirical model was then built so as to assess the main and cross-variable effects on the reaction conversion and also to maximize biodiesel production for each enzyme. For the system containing Novozym 435 as tatalyst the maximum conversion obtained was 81.4% at 65°C, enzyme concentration of 20 wt/wt%, water concentration of 0 wt/wt%, and oil-to-ethanol molar ratio of 1∶10. When the catalyst was Lipozyme IM, a conversion as high as 98% was obtained at 65°C, enzyme concentration of 20 wt/wt%, water concentration of 0 wt/wt%, and oil-to-ethanol molar ratio of 1∶3.
Journal of Supercritical Fluids, 2008
Journal of Supercritical Fluids, 2001
... Also, to the best of our knowledge, there is no comprehensive study available comparing conve... more ... Also, to the best of our knowledge, there is no comprehensive study available comparing conventional and supercritical media for this reaction. ... For this purpose, a Taguchi experimentaldesign with two levels and four variables was adopted for each system to allow the ...
Journal of Supercritical Fluids, 2006
Applied Biochemistry and Biotechnology, 2006
Inulinase is an enzyme relevant to fructose production by enzymatic hydrolysis of inulin. This en... more Inulinase is an enzyme relevant to fructose production by enzymatic hydrolysis of inulin. This enzyme is also applied in the production of fructo-oligosaccharides that may be used as a new food functional ingredient. Commercial inulinase is currently obtained using inulin as substrate, which is a relatively expensive raw material. In Brazil, the production of this enzyme using residues of sugarcane and corn industry (sugarcane bagasse, molasses, and corn steep liquor) is economically attractive, owing to the high amount and low cost of such residues. In this context, the aim of this work was the assessment of inulinase production by solid state fermentation using by Kluyveromyces marxianus NRRL Y-7571. The solid medium consisted of sugar cane bagasse supplemented with molasses and corn steep liquor. The production of inulinase was carried out using experimental design technique. The effect of temperature, moisture, and supplements content were investigated. The enzymatic activity reached a maximum of 445 units of inulinase per gram of dry substrate.
Bioresource Technology, 2009
Journal of Supercritical Fluids, 2008
... Accordingly, these facts may explain the little influence of pressure on the reaction convers... more ... Accordingly, these facts may explain the little influence of pressure on the reaction conversion. ... This result may be of technological importance, as a relatively small amount of solvent seems to be sufficient for conducting enzymatic production of biodiesel, with clear advantage ...
Applied Biochemistry and Biotechnology, 2005
This article reports experimental data on the production of fatty acid ethyl esters from refined ... more This article reports experimental data on the production of fatty acid ethyl esters from refined and degummed soybean oil and castor oil using NaOH as catalyst. The variables investigated were temperature (30–70°C), reaction time (1–3 h), catalyst concentration (0.5–1.5 w/wt%), and oil-to-ethanol molar ratio (1:3–1:9). The effects of process variables on the reaction conversion as well as the optimum experimental conditions are presented. The results show that conversions >95% were achieved for all systems investigated. In general, an increase in reaction temperature, reaction time, and in oil-to-ethanol molar ratio led to an enhancement in reaction conversion, whereas an opposite trend was verified with respect to catalyst concentration.
Journal of Chemical Technology and Biotechnology, 2008
BACKGROUND: Lipase production by Penicillium simplicissimum using soybean meal as substrate has b... more BACKGROUND: Lipase production by Penicillium simplicissimum using soybean meal as substrate has been investigated. A factorial design technique was used to evaluate the effects of incubation temperature, initial moisture of the meal and substrate supplementation with low cost supplements, on lipase production. Soybean oil and wastewater from a slaughterhouse, which is rich on oil and fat, corn steep liquor and yeast hydrolysate, were tested as supplementary carbon and nitrogen sources.RESULTS Cultivation conditions were optimized for the production of lipase by factorial design and response surface methodology. Results show that the microorganism produces very low protease activity (0.21 U gds−1 dry substrate), which helps to maximize lipase production. Soybean meal without supplements appears to be the best medium of those tested for lipase production by P. simplicissimum.CONCLUSION: This work showed that temperature and moisture are the factors that most strongly influence lipase production by P. simplicissimum using soybean meal as substrate. The growth conditions that optimize lipase production are 27.5 °C using substrate with 550 g kg−1 of initial moisture. In optimum conditions lipase activity of 30 U gds−1 dry substrate was obtained. Copyright © 2007 Society of Chemical Industry
Journal of Molecular Catalysis B-enzymatic, 2006
This work investigated the influence of temperature, pressure, exposure times and depressurizatio... more This work investigated the influence of temperature, pressure, exposure times and depressurization rate on the activity of a non-commercial immobilized lipase from Yarrowia lipolytica (YLL) submitted to compressed carbon dioxide, propane and n-butane. A high-pressure cell was employed in the experiments, in the pressure range of 10–280bar, varying the temperature from 35 to 75°C, exposure times from 1 to 6h,
Industrial & Engineering Chemistry Research, 2000
Journal of Supercritical Fluids, 2006
Journal of Food Engineering, 2009
Ciencia E Tecnologia De Alimentos, 2002
A erva-mate é uma matéria-prima de grande importância para a região Sul do Brasil, sendo que a pr... more A erva-mate é uma matéria-prima de grande importância para a região Sul do Brasil, sendo que a produção anual é de aproximadamente 650.000 toneladas de folhas. Atualmente, problemas com o excesso de oferta têm incentivado pesquisadores e empresários a buscar alternativas para a utilização da erva-mate como matéria-prima para o desenvolvimento de novos produtos bem como promover melhorias no processamento industrial visando a obtenção de características organolépticas desejáveis. Neste sentido, o presente trabalho teve por objetivo realizar a caracterização físico-química da erva-mate em função das etapas do processamento industrial (sapeco, secagem e tempo de cancheamento) e verificar como estas etapas influem nos teores de cinzas, fibras, gorduras, proteínas, glicose, sacarose e cafeína presentes na matéria-prima. Os resultados obtidos permitiram verificar que as etapas do processamento industrial influem diretamente nos teores dos compostos citados, mostrando a relevância em se analisar estes resultados quando o objetivo é utilizar esta matéria-prima para o desenvolvimento de novos produtos alimentícios que podem exigir características específicas.
Journal of Supercritical Fluids, 2005
Applied Biochemistry and Biotechnology, 2004
The production of lipases by Penicillium simplicissimum using solid-state fermentation and soy ca... more The production of lipases by Penicillium simplicissimum using solid-state fermentation and soy cake as substrate was investigated. The effects of temperature, cake moisture, and carbon supplementation on lipase production were studied using a two-level experimental plan. Moisture, pH, and lipase activity were followed during fermentation. Statistical analysis of the results was performed to evaluate the effect of the studied variables on the maximum lipase activity. Incubation temperature was the variable that most affected enzyme activity, showing a negative effect. Moisture and carbon supplementation presented a positive effect on activity. It was possible to obtain lipase activity as high as 21 U/g of dry cake in the studied range of process variables.
Bioprocess and Biosystems Engineering, 2008
Current studies about lipase production by solid-state fermentation involve the use of agro-indus... more Current studies about lipase production by solid-state fermentation involve the use of agro-industrial residues towards developing cost-effective systems directed to large-scale commercialization of enzyme-catalyzed processes. In this work, lipase production and partial characterization of the crude enzymatic extracts obtained by Penicillium verrucosum using soybean bran as substrate was investigated. Different inductors were evaluated and the results showed that there is no influence of this variable on the lipase production, while temperature and initial moisture were the main factors that affected enzyme production. The optimized cultivation temperature (27.5 °C) and initial moisture of substrate (55%) were determined using the response surface methodology. Kinetics of lipase production was followed at the optimized growth conditions. Optimum lipase yield was 40 U/g of dry bran. The crude enzymatic extract showed optimal activity in the range from 30 to 45 °C and in pH 7.0.