José Marques Pereira

Modelagem matemática da secagem em camada delgada de bagaço de uva fermentado

The objective of this work was to determine the drying characteristics of fermented grape pomace in a hot air-dryer, to evaluate the descriptive capacity of known mathematical models of thin-layer drying, and to establish the values of effective diffusivity and activation energy. Drying experiments were conducted at 50, 60, 70, 80 and 90oC, with 1.0 m s-1 air-drying velocity. Ten different mathematical models for thin-layer drying were compared, according to the values of coefficient of determination (R2), chi-square (χ2), residual mean square root (RMSR), and relative mean error (P) estimated by the drying curves. The effects of drying temperature on the coefficients and constants were predicted by the regression models. The modified Page model was selected to represent the behavior of thin-layer drying of grape pomace. The mean values of effective diffusivity varied from 1.0091 x 10-9 m2 s-1 to 3.0421 x 10-9 m2 s-1, at the evaluated temperatures. Effective diffusivity dependence on temperature was described by the Arrhenius equation, with activation energy of 24.512 kJ mol-1.

The efficiency of electrocoagulation in treating wastewater from a dairy industry, Part I: Iron electrodes

Iron electrodes were used for electrocoagulation (EC) treatment of wastewater from a dairy plant. Electrolysis time, pH, current density and distance between electrodes were considered to assess the removal efficiency of chemical oxygen demand (COD), total solids (TS) and their fractions and turbidity. Samples were collected from the effluent of a dairy plant using a sampling methodology proportional to the flow. The treatments were applied according to design factorial of half fraction with two levels of treatments and three repetitions at the central point. The optimization of parameters for treating dairy industry effluent by electrocoagulation using iron electrodes showed that electric current application for 15 minutes, an initial sample pH close to neutral (pH 7.0) and a current density of 50 A . m−2 resulted in a significant reduction in COD by 58 %; removal of turbidity, suspended solids and volatile suspended solids by 95 %; and a final treated effluent pH of approximately 9.5. Negative consequences of the type of electrode used were the emergence of an undesirable color and an increase in the proportion of dissolved solids in the treated effluent.

Estrutura do pasto disponível e do resíduo pós-pastejo em pastagens de capim-cameroon e capim-marandu

Two experiments were carried out to evaluate structural characteristics and crude protein concentration of Pennisetum purpureum cv. Cameroon and Brachiaria brizantha cv. Marandu under four rotational stocking rates. During the rainfall period, the studied stocking rates for both pastures were 3, 4, 5, and 6 steers/ha and in the dry period the stocking rates were 2, 3, 4, and 5 steers/ha. In both experiments, elephantgrass cv. Cameroon produced greater total herbage mass and green herbage mass, which decreased with the increase in defoliation as a result of the used stocking rates, mainly during the dry period. For elephantgrass pastures, the increase in stocking rate had a greater negative effect on the green leaf blade dry matter fraction. In the rainfall period, the stocking rates which promoted greater herbage allowance, green herbage mass, and leaf blade fraction were 5 steers/ha and 4 steers/ha for elephantgrass cv. Cameroon and marandugrass, respectively. In the dry period, greater values for these variables were obtained with 4 steers/ha and 3 steers/ha, respectively. Stocking rates did not influence crude protein concentration of the grasses, with leaf blade presenting higher concentration of this nutrient.

Dinâmica de perfilhamento e fluxo de biomassa em capim-cameroon sob lotação rotativa

The population dynamics of tillers and tissue turnover were investigated in pastures of Pennisetum purpureum Schum. cv. Cameroon submitted to different stocking rates under rotational stocking. Two experiments were carried out and the experimental area was characterized by a mean annual rainfall of 1,311 mm and average temperature of 25oC. In the rainfall period the stocking rates were 3, 4, 5, and 6 steers/ha; in the dry period the stocking rates were 2, 3, 4, and 5 steers/ha. The most intensive grazing lead to the greatest number of basal tillers, with values ranging from 59.02 to 57.75 and 64.64 to 81.36 tillers/m2 for the stocking rates of 5 to 6 and 4 to 5 steers/ha in the rainfall and dry periods, respectively. Considering the aerial tillers, cameroon grass showed 350.83 and 278.05 tillers/m2 for the stocking rates of 5 to 6 steers/ha, in the period of rainfall. In the dry period, the stocking rate of 4 steers/ha lead to 399.20 aerial tillers/m2. Increasing stocking rates reduced the daily stem elongation. Leaf appearance rate (TApF) and leaf elongation rate (TAIF) did not differ among stocking rates neither differed between experiments; TapF ranged from 0.10 and 0.13 live leaves/day and TAIF ranged from 0.82 and 1.36 cm/leaf/day. The average number of live leaves/tiller was 8.04 and 9.51 for the rainfall and dry period, respectively, decreasing with increasing stocking rate.

Expanded-Bed Adsorption Utilizing Ion-Exchange Resin to Purify Extracellular β-Galactosidase

The application of expanded-bed ion-exchange resins allows the elimination of intermediary particulate separation steps like filtration or centrifugation prior to adsorption steps in enzyme-purification processes from crude fermentation broths. This work is concerned with the experimental evaluation data of a process related to the adsorption of an extracellular p-galactosidase from the fungiScopulariopsis. The protein recovery in the ion-exchange resin Accell Plus QMA™ was accomplished using a continuous-monitoring method. The direct adsorption step was followed by a elution step with concentrated NaCl solutions aiming to improve the enzyme-specific activity. Experimental data for fixed and expanded bed were compared

‘Light’ fraction mineralization potentials of humid tropical soils

Soil samples from a rainforest, a papaya plantation, a pure Brachiaria humidicola pasture and a B. humidicola/Desmodium ovalifolium mixture were analyzed for fertility parameters. Soils were sieved to >100 µm and the organic matter light fraction was obtained by 1.8 g mL−1 density separation in a sodium polytungstate solution which was subsequently incubated under anaerobic conditions. The effect of different density agents (sodium polytungstate, Ludox and sodium iodide) on mineralization was also tested on a temperate and a tropical soil and on maize tissue.

Nutritional divergence in genotypes of forage peanut

The objective of this study was to evaluate the nutritional divergence between ten genotypes of forage peanut, based on chemical composition as well as fermentation and in vitro degradation kinetic characteristics. Treatments consisted of ten genotypes of Arachis pintoi, namely eight accessions (31135, 30333, 15121, 31828, 15598, 31534, 13251 and 31496) and two cultivars (cv. Belmonte and cv. Amarillo). The genotypes were harvested in each plot at a height of 3 cm from the ground, in 42-day intervals, during the time of heaviest rainfall. For the multivariate analysis the following variables, the following were used: crude protein, neutral detergent fiber, potential degradation in 48 hours, degradation rate of insoluble potentially degradable fraction and degradation rate of non-fibrous carbohydrate. The application of the hierarchical clustering analysis, using the Euclidian distances matrix of standardized averages allowed for the identification of five homogeneous groups. Among them, the accessions 31828, 31534, 15121 and cv. Belmonte stood out nutritionally among the remaining genotypes evaluated, depicting as promising for the utilization in ruminant feeding.

Biomass turnover in brachiaria cultivars in a tropical environment

The experiment was conducted to evaluate the morphogenetic traits of three Brachiaria cultivars (common, Llanero and Tupi) subjected to continuous grazing with variable stocking rate in the four seasons of the year. A randomized block design with five replicates was adopted. Tissue turnover evaluations were carried out in the summer, fall, winter and spring, with measurements taken every two days. Stem length and the length of each green leaf were measured. With these determinations, the following variables were calculated: stem elongation rate (cm/tiller/day), leaf elongation rate (cm/leaf/day), number of live leaves per tiller and phyllochron (days/leaf). The highest leaf appearance rate was obtained by Tupi grass in the summer, and the lowest by Llanero grass in the winter. The lowest phyllochron, 5.90 days/leaf, was obtained by Tupi grass in the winter, whereas in commercial cultivars Llanero and common the average phyllochron was 9.04 and 10.04 days/leaf, respectively. Because of the effect of the transition from the dry season to the beginning of rains in the summer, this was the period of greatest variations in results among the different cultivars. Llanero grass stood out for the highest values for plant, tiller and leaf lengths, resulting from greater stem and leaf elongation rates. Tupi grass had the worst performance of all cultivars.

Valor alimentício do capim marandu, adubado ou consorciado com amendoim forrageiro, e características da carcaça de bovinos de corte submetido à pastejo rotacionado

The objective of this study was to evaluate the chemical composition of the pasture Brachiaria Brizantha intercropped with peanut or fertilized with N and carcass characteristics of beef cattle. The pasture was managed under rotational grazing with stocking continues, with variable stocking, using 16 Nellore bulls. In the evaluation of dry matter production total green significance was observed between treatments and periods evaluated, and treatment consortium presented a higher average. The variable crude protein showed significance between treatments and periods. The NDT and FDN had no significant effect on the evaluation of the grass. Periods had lower ADG were the 4th and 6th periods. For the PB, FDN and NDT legume 3rd period showed the lowest averages. For variables GMD, NAD, GPC showed statistical significance for the interaction, and the 1st treatment period consortium submitted the highest averages. In the treatment of the largest fertilizer stocking rates were achieved in stations where chemical fertilization occurred. Statistical significance was observed for the variable conformation carcass classification. The consortium forage peanut cv. Belmonte may be using to replace fertilization with 120kg / N / ha, as it ensures even weight gain per animal, without changing the commercial carcass traits.

Extração, purificação e avaliação da atividade da glutationa S-Transferase de fígado bovino

Considerando a acao detoxificante da enzima Glutationa S-Transferase (GST), importante contra o estresse oxidativo, câncer e outras doencas degenerativas, com este estudo, objetivou-se avaliar a atividade dessa enzima extraida de figado bovino e avaliar a estabilidade em condicoes de refrigeracao (5 0C). O figado bovino foi selecionado por ser materia prima disponivel comercialmente e de baixo custo. A extracao foi realizada em quatro etapas (homogeneizacao/centrifugacao, passagem em coluna contendo dietilaminoetil-celulose (DEAE-celulose), precipitacao com sulfato de amonia e passagem em coluna contendo Carboximetilcelulose (CMC). O extrato obtido apresentou atividade com o 1 cloro 2, 4 dinitrobenzeno, na presenca de glutationa reduzida. O extrato final apresentou atividade especifica 5 vezes maior que o extrato bruto centrifugado e estabilidade da atividade enzimatica foi mantida nas condicoes de 50C, durante 70 dias.