Optimum design of experiments for statistical inference

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

A metodologia de superfície de resposta como ferramenta para a avaliação da produção de alginato e poli-hidroxibutirato pela Azotobacter vinelandii

The response surface methodology as a tool for assessing the production of alginate and polyhydroxybutirate by Azotobacter vinelandii. Alginate is a polysaccharide extracted from cell walls of brown algae and used in the food, pharmaceuticals and biotech industries. Production is concentrated on the cultivation of brown seaweed, but several bacteria of the genus Pseudomonas and Azotobacter produce alginate. The chemical structure of alginates produced by algae is similar to those synthesized by A. vinelandii. The bacteria also produce intracellular polymers such as polyhydroxybutyrate (PHB), known as bioplastic. This work studied the simultaneous alginate and PHB production by A. vinelandii using sucrose and different parameters of fermentation in an orbital shaker. The optimal values for the production of these compounds were determined by the MSR. The first experiment was a 2(6-2) factorial design. The second was based on significant variables of the first, resulting in a full 3(3-0) factorial design. From the first to the second, an increase was observed in the PHB productivity from 12 to 45 mg g(-1) cell h(-1) and alginate from 100 to 1,600 mg g(-1) of cell h(-1). The productivity of both compounds was in the maximum incubation temperature of 62 degrees C, in the shortest time of incubation (18h) and the sucrose concentration, 11 g L(-1). In both experiments the PHB extracted presented purity of 94%.

Produção de biomassa por fungos Filamentosos em meio de vinhaça de cana-de-açúcar suplementado com melaço

Three species of filamentous fungi, Aspergillus niger, Penicillium fellutanum and Mucor hiemalis, were selected and cultivated in vinasse media with different addition of molasses, pasteurized to 85°C for 30 minutes and with pH = 5.0. The microorganisms, previously adapted to the respective medium for 48 hours, from a solution of 107 spores.ml-1, were cultivated in pure and mixed cultures in Erlenmeyer vessel of 500ml, to 30°C, with constant agitation of 170 rpm, for 24, 48 and 72 hours, with four repetition for each samples. The biomass was separated by vacuum filtration in filter Whatman #1 and dried in oven at 105°C until right weight, the obtained liquid was submited to COD analysis. The datas were statistically analysed using a response surface methodology, to improve the effect on the molasses proportion and culture time, in the biomass production by microorganism in research. According to the obtained results (5.02% of molasses, 55.59h, 70% of spores solution of A. niger and 30% of spores solution of P. fellutanum), cultivating was carried out in Microferm Fermentor New Brunswick for 48 hours at 300 rpm, aired at 1v/v/m, using 5 liters of medium added with 5.0% of molasses on the conditions above described. The average of the results obtained (6.81g.l-1) was higher than the confidence interval (5.937 ; 6.369) and was inside the prediction interval (4.471 ; 7.834) both of them significant at 95% by the statistical test employed.

Influence of carrageenan and total solids content on the rheological properties of lactic beverage made with yogurt and whey

The purpose of this work was to study the influence of carrageenan level (X 1) and total solids content of yogurt/whey mixture (X 2) on starter culture fermentation time, physicochetnical properties (pH, fat and total solids contents) and rheological characteristics of lactic beverages using response surface methodology. The physicochemical characteristics of the lactic beverages were similar to those of commercial products. All beverages showed non-Newtonian fluid behavior with thixotropy and yield stress. The total solids content of the lactic beverages had a greater influence on the rheological behavior of these products than the carrageenan level. Wide ranges of consistency measurements were observed by varying the stabilizer level and total solids content.

Simultaneous effects of total solids content, milk base, heat treatment temperature and sample temperature on the rheological properties of plain stirred yogurt

Response surface methodology was used to establish a relationship between total solids content, milk base, heat treatment temperature, and sample temperature, and consistency index, flow behaviour index, and apparent viscosity of plain stirred yogurts. Statistical treatments resulted in developments of mathematical models. All samples presented shear thinning fluid behaviour. The increase of the content of total solids (9.3-22.7 %) and milk base heat treatment temperature (81.6-98.4°C) resulted in a significant increase in consistency index and a decrease in flow behaviour index. Increase in the sample temperature (1.6-18.4°C) caused a decrease in consistency index and increase in flow behaviour index. Apparent viscosity was directly related to the content of total solids. Rheological properties of yogurt were highly dependent on the content of total solids in milk.

Cyclodextrin glycosyltransferase production by the Bacillus sp., subgroup alcalophilus using a central composite design

Cyclodextrin glycosyltransferase (CGTase) activity was produced by the Bacillus sp., subgroup alcalophilus in a culture medium containing cassava starch. A central composite design and response surface methodology were used to study the influence of carbon source (cassava starch), nitrogen sources (yeast extract and tryptone) and sodium carbonate in the production medium. Assays were performed in 300 mL Erlenmeyer flasks containing 100 mL of production medium maintained in a shaker at 150 rpm at 35±1°C for 72 h of fermentation. The independent variables [0.75% cassava starch, nitrogen sources (0.375% yeast extract and 0.375% tryptone) and 1% Na2CO3] produced an enzyme activity of 96.07 U mL-1.© Academic Journals Inc.

Aplicação da metodologia de superfície de resposta na remediação de um solo arenoso contaminado artificialmente com cobre

Soil flushing is an alternative remediation technology for soils contaminated with heavy metals, which the main contaminant removing process consists in percolating an extraction solution. This work aimed to use the response surface methodology to point out combinations among the parameters of the extraction solution (Na2EDTA concentration, volume e pH) in order to reduce the concentration of copper in a sandy soil to risk levels lower than the intervention levels for exposure scenarios adopted by the Environmental Company of Sao Paulo State. Thus, a series of tests in leaching columns were carried out using a Fluvisol artificially contaminated (1257,3 mg kg-1). The tests were conducted in triplicate and setup a central composite rotatable design with 15 different parameters combinations of the extraction solution and one replicate in the center point. Using 5% significance level, the adjusted model (R2 = 0,98) indicated combinations of Na2EDTA concentration, pH and volume of the extraction solution which allow reduction of copper concentration below levels reported by environmental agency of Sao Paulo State for industrial, residential, agricultural or maximum exposure scenarios.

Agaricus blazei as a Substrate for the Production of β-1,3-Glucanase by Trichoderma harzianum Rifai

Extracellular β-1,3-glucanase was produced by Trichoderma harzianum Rifai cultivated in the Agaricus blazei (Agaricus brasiliensis) extract as a substrate in submerged fermentation. A 22-central composite factorial design was developed using the time of culture (x1/day) and Agaricus blazei extract concentration (x2/(g/L)) as variables, and the results were analyzed using response surface methodology (RSM). The results showed that the Agaricus blazei extract concentration was the most important variable in the production of β-1,3-glucanase, and the maximum β-1,3-glucanase activity (0.77 U/mL) was obtained in one day of cultivation. The β-glucan present in the cell wall of Agaricus blazei mushroom proved to be a good substrate for inducing the production of specific β-1,3-glucanase by Trichoderma harzianum Rifai.

Time and temperature on the storage of oocytes from jundiá catfish, Rhamdia quelen

The objective of this study was to evaluate the effects of three water and storage temperatures on the oocytes of the jundiá catfish, Rhamdia quelen. A factorial experimental design over time, with treatments completed in triplicate every 48 h, was used (5 × 3 × 3 × 3) to study the exposure of the oocytes to temperatures of 15, 25 and 35. °C and activated with water at 15, 25 and 35. °C each at 0, 45, 90, 135 and 180 minutes post-collection. Linear regression analysis for the response surface model indicated an interaction (p<0.05) between time and temperature of exposure with greater values for fertilization, hatching and normal larvae rates at the time of oocyte collection (70.2 ± 8.4% fertilized oocytes, 66.7 ± 29.4% hatched eggs and 30.3 ± 25.0% normal larvae). According to the statistical model, the water temperature that resulted in the highest fertilization rate was 25.6. °C (p<0.05). The rates of fertilization, hatching and normal larvae correlated positively (p<0.05) with one another, showing that these parameters can be used in the measurement of oocyte quality. Artificial fertilization of oocytes is recommended immediately after collection; if storage is necessary, it should be carried out at 15. °C. © 2011 Elsevier B.V.

Keratinase production by new strain of Bacillus Amyloliquefaciens: Application of statistical experimental design for optimization of keratinase production

Feathers are rich in amino acids and can be employed as a dietary protein supplement for animal feed. Microbial degradation is an alternative technology for improving the nutritional value of feathers. Other potential applications of keratinase include use in the leather industry, detergents and medicine as well as the pharmaceutical for the treatment of acne, psoriasis and calluses. A new keratinolytic enzyme production bacterium was isolated from a poultry processing plant. To improve keratinase yield, statistically based experimental designs were applied to optimize three significant variables: temperature, substrate concentration (feathers) and agitation speed. Response surface methodology demonstrated an increase in keratinolytic activity at temperature, agitation speed and substrate concentration of 26.6°C, 150 rpm and 2%, respectively. Liquid chromatography revealed the release of amino acids in the Bacillus amyloliquefaciens culture broth, thereby demonstrating the potential of feather meal in the animal feed industry. © Global Science Publications.

Optimisation of High Hydrostatic Pressure Processing of Pêra Rio Orange Juice

The influence of high hydrostatic pressure (HHP) on Pêra Rio orange juice was investigated using response surface methodology. A central composite design was used to evaluate the effects of three processing conditions (independent variables), namely pressure (100-600 MPa), temperature (30-60 °C) and time (30-360 s), on the native microflora and pectin methylesterase (PME) activity of orange juice. Analysis of variance showed that second-order polynomial models fitted well with the experimental data for PME residual activity (R2 = 0.9586, p < 0.001) and aerobic microorganism count (R2 = 0.9879, p < 0.001). The optimum HHP processing conditions to produce orange juice with PME residual activity of less than 20 % and low microorganism count (<2 log cycles CFU/mL) were 550 to 600 MPa, 55 to 60 °C and 330 to 360 s. © 2013 Springer Science+Business Media New York.

Extrusion of flavored corn grits: Structural characteristics, volatile compounds retention and sensory acceptability

The effects of the moisture content of the raw material, extrusion temperature and screw speed on flavor retention, sensory acceptability and structure of corn grits extrudates flavored with isovaleraldehyde, ethyl butyrate and butyric acid were investigated. Higher temperature resulted in more expanded extrudates with lower density and cutting force, while higher moisture content increased ethyl butyrate retention. The most acceptable extrudates were those obtained with low moisture content, under conditions of high extrusion temperature and high screw speed, or low screw speed and low extrusion temperature, whereas the aroma intensity closest to the ideal was observed under conditions of low extrusion temperature and low moisture content of the raw material. © 2013 Elsevier Ltd.

Produção de xilanases por Aspergillus niger utilizando planejamento experimental: purificação de xilanase

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Adição de precursores em meio complexo solúvel para a produção de Cefamicina C por Streptomyces clavuligerus

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Impacto da tecnologia de alta pressão hidrostática sobre a qualidade do suco de laranja

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)