EQA - Artigos Publicados em Periódicos
URI permanente para esta coleçãohttps://rihomolog.furg.br/handle/1/1611
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- ItemOptimization of deacetylation in the production of chitosan from shrimp waste: use of response surface methodology(Elsevier, 2007) Weska, Raquel; Moura, Jaqueline Motta de; Batista, Lucia de Moraes; Rizzi, Jaques; Pinto, Luiz Antonio de AlmeidaThe use of chitosan in diverse areas is directly related to the polymer’s molecular weight and degree of deacetylation, which depends on the conditions of chitin deacetylation. The aim of the present study consisted of optimization of the deacetylation stage in the production of chitosan, using the response surface methodology for the polymer’s molecular weight. Chitin was obtained from shrimp wastes and the study of deacetylation made through a factorial experimental design, where temperature and time were varied. The estimate of chitosan’s intrinsic viscosity was made by linear regression with the values of reduced viscosity and concentration, using Huggins equation for polymers. The viscosity average molecular weight of chitosan was calculated for each experiment by the equation by Mark–Houwink–Sakurada that relates the intrinsic viscosity to the polymer’s molecular weight. The optimum condition for the deacetylation reaction for molecular weight was observed at a temperature of 130 °C and in 90 min, and corresponded to a molecular weight of chitosan of about 150 kDa, and a deacetylation degree of 90%.
- ItemGalacto-oligosaccharides production using permeabilized cells of kluyveromyces marxianus(De Gruyter, 2010) Manera, Ana Paula; Costa, Fátima Aparecida de Almeida; Rodrigues, Maria Isabel; Kalil, Susana Juliano; Maugeri Filho, FranciscoGalacto-oligosaccharides are non-digestible carbohydrates and are recognized as important prebiotics for than stimulation of the proliferation of lactic acid bacteria and bifidobacteria in the human intestine. GOS can be produced by a transgalactosylation reaction catalysed by β-galactosidase enzyme, and microorganisms can be used as a source of β-galactosidase. In this work, a process for producing GOS using permeabilized cells of Kluyveromyces marxianus CCT 7082 was proposed. The effects of the concentrations of lactose and enzyme, temperature and pH were studied using a fractional design followed by a central composite rotatable design. The optimum conditions for galacto-oligosaccharides production were found to be: lactose concentration 500 g/L, enzyme concentration 10 U/mL, 45°C and pH 7.0. Under optimized conditions, the GOS concentration, yield and productivity were 83 g/L, 16.5% and 27.6 g/L.h, respectively.
- ItemUtilização de resíduos agroindustriais em processo biotecnológico para produção de B-galactosidase de Kluyveromyces marxianus CCT 7082(2011) Manera, Ana Paula; Ores, Joana da Costa; Ribeiro, Vanessa Amaral; Rodrigues, Maria Isabel; Kalil, Susana Juliano; Maugeri Filho, FranciscoO objetivo deste trabalho foi avaliar a composição do meio de cultura para a produção da enzima B-galactosidase de Kluyveromyces marxianus CCT 7082 utilizando a técnica de delineamento experimental. A produção da enzima foi realizada em meio composto por soro de queijo, água de maceração de milho (AMM) e hidrolisado de levedura Prodex-lac® e sais. Foi realizado um planejamento experimental fracionário (25-1) para determinar as variáveis significativas na produção da enzima. Foram testadas diferentes concentrações de lactose presente no soro de queijo (10 a 70 g L-1), AMM (10 a 100 g L-1), Prodex-lac (4 a 20 g L-1), (NH4)2SO4 (0 a 10 g L-1) e o pH (5 a 7). As variáveis concentração de lactose, AMM e o pH apresentaram efeito estatisticamente significativo na atividade enzimática dentro das faixas estudadas, sendo estas variáveis empregadas num delineamento composto central rotacional para otimizar a produção da enzima. As faixas testadas foram: concentração de lactose de 40 a 100 g L-1, AMM de 10 a 120 g L-1 e pH de 3,5 a 6,5. As condições que resultaram em maior atividade enzimática (1400 U g-1) foram 70 g L-1 de lactose, 65 g L-1 de AMM, 4 g L-1 de Prodex-lac e pH 5, obtendo uma produtividade de 61 U L-1 h-1.
- ItemExperimental Design as a Tool for Optimization of C-Phycocyanin Purification by Precipitation from Spirulina platensis(2009) Silva, Lorena Aguiar da; Kuhn, Kátia Regina; Moraes, Caroline Costa; Burkert, Carlos André Veiga; Kalil, Susana JulianoC-phycocyanin is a natural blue dye that has been used as an additive in food and can be used to produce medications. The major goal of the present study was to obtain C-phycocyanin under the best operational conditions for high C-phycocyanin recovery and purity using the precipitation technique. Crude C-phycocyanin from Spirulina platensis was used. Optimization of the purification was carried out using experimental design. The effect of ammonium sulfate concentration, volume and of pH for resuspension were evaluated. Subsequently an ammonium sulfate fractionation study was carried out using the most suitable conditions found in the experimental design. The best purification condition was ammonium sulfate fractionation at 0-20%/20-50%, in relation to a resuspension volume/initial volume of 0.52 in a 7.0 pH buffer. Under these conditions, in an one-step purification only, the purity increased 70% compared to the initial extract, with an 83.8% recovery.
- ItemProduction of a rhamnolipid-type biosurfactant by Pseudomonas aeruginosa LBM10 grown on glycerol(2010) Rosa, Célia Francisca Centeno da; Michelon, Mariano; Burkert, Janaina Fernandes de Medeiros; Kalil, Susana Juliano; Burkert, Carlos André VeigaThe work herewith investigated the effect of the culture medium composition on rhamnolipid production by Pseudomonas aeruginosa LBM10, previously isolated from an estuarine environment in Southern Brazil. Experimental design and surface response methodology were used in order to improve biosurfactant production using glycerol, a renewable carbon source. The assays were carried out in a rotary shaker at 30°C and 180 rpm for 120 h and the parameters studied were glycerol concentration, C/N (carbon/nitrogen) and C/P (carbon/phosphorus) ratios. Low glycerol concentration and a phosphorus-limiting condition were favorable for rhamnolipid production. Contour plots constructed by predictive polynomial equations led to a glycerol concentration of 13.2 g/l, a C/N ratio of 12.8 and a C/P ratio of 40 in order to maximize rhamnolipid concentration (4.15 g/l) associated with a high emulsification index (61%).