Showing papers in "Brazilian Journal of Chemical Engineering in 2012"

Use of ionic liquids in biodiesel production: a review

Abstract: This paper discusses the feasibility of the use of ionic liquids as catalysts in the biodiesel production field, describing some studies already published in the literature on this theme. Ionic liquids are regarded as a new generation of catalysts in the chemical industry, with several uses in different commercial segments. However only a few publications involving this topic can be found in the literature addressing the manufacture of biodiesel from vegetable oils or animal fats. Through the analysis of the data generated in the studies reviewed, it is possible to affirm that ionic liquids present great potential as catalysts for biodiesel production, but there are some challenges to be faced, such as the production of ionic liquids with low cost, easy recovery and with the possibility of reutilization of the catalyst for several cycles.

Computational modelling of MHD unsteady flow and heat transfer toward a flat plate with Navier slip and Newtonian heating

Abstract: The combined effects of Navier slip and Newtonian heating on an unsteady hydromagnetic boundary layer stagnation point flow towards a flat plate in the presence of a magnetic field are studied. The self-similar equations are obtained using similarity transformations and solved numerically by a shooting algorithm with a Runge-Kutta Fehlberg integration scheme. The velocity profiles, temperature profiles, the local skin friction coefficient, and the local Nusselt number are computed and discussed in details for various values of the different parameters. Numerical results are presented both in tabular and graphical forms, illustrating the effects of these parameters on the thermal and concentration boundary layers. It is revealed that the thermal boundary layer thickens with a rise in the flow unsteadiness and as Newtonian heating intensifies, while the local skin friction and the rate of heat transfer at the plate surface change significantly due to the slip parameter.

Improvement of the flocculation process in water treatment by using moringa oleifera seeds extract

Abstract: Water scarcity encourages researchers to keep working on natural coagulant agents such as Moringa oleifera seed extract, that could be used even in developing countries. With this scope, this investigation is focused on the optimization of certain parameters affecting the use of this coagulant product in the clarification of real surface water. Acidic pH levels seem to enhance the coagulation performance and the turbidity removal increases as the stirring period becomes longer (up to 95% with 40 min). The optimum stirring rate is identified as 80 rpm. Water clarified with this optimum coagulation and flocculation process is turbidity-competitive with other well known coagulants and flocculants and its quality is inside standard ranges for clarified water. No microbial growth is observed within the first 72 hours after the coagulant trials.

Characterization of lyophilized liposomes produced with non-purified soy lecithin: a case study of casein hydrolysate microencapsulation

Abstract: A commercial casein hydrolysate was microencapsulated in liposomes produced with non-purified soy lecithin, cryoprotected with two different disaccharides and lyophilized. The encapsulation efficiency of casein hydrolysate ranged from 30 to 40%. The powders were analyzed by differential scanning calorimetry (DSC), scanning electron micrography (SEM), infrared spectroscopy (FTIR) and wide angle X-ray diffraction (WAXD). DSC data revealed the presence of an exothermal transition in empty lyophilized liposomes, which was ascribed to the presence of a quasicrystalline lamellar phase (intermediary characteristics between the Lβ and Lc phases). The addition of peptides to the liposomal system caused the disappearance of this exothermic phenomenon, as they were located in the polar headgroup portion of the bilayer, causing disorder and preventing the formation of the quasicrystalline phase. Infrared data indicated the presence of the peptides in the lyophilized formulations and showed that the cryoprotectants interacted effectively with the polar heads of phospholipids in the bilayer.

Production of hydrogen in the reaction between aluminum and water in the presence of NaOH and KOH

Abstract: The objective of this work is to investigate the production of hydrogen as an energy source by means of the reaction of aluminum with water. This reaction only occurs in the presence of NaOH and KOH, which behave as catalysts. The main advantages of using aluminum for indirect energy storage are: recyclability, non-toxicity and easiness to shape. Alkali concentrations varying from 1 to 3 mol.L-1 were applied to different metallic samples, either foil (0.02 mm thick) or plates (0.5 and 1 mm thick), and reaction temperatures between 295 and 345 K were tested. The results show that the reaction is strongly influenced by temperature, alkali concentration and metal shape. NaOH commonly promotes faster reactions and higher real yields than KOH.

Pore blocking mechanism for the recovery of milk solids from dairy wastewater by ultrafiltration

Abstract: - This paper evaluates the pore blocking mechanism of two ultrafiltration membranes with different geometries (tubular and spiral wound) when dairy wash water is filtered The work evaluated the effect of transmembrane pressure and the cross-flow velocity with a 3 2 experimental design using classical Hermia’s models and the resistance-in-series model The resistance-in-series analysis identified external fouling on the surface of both membranes, but the tubular membrane showed higher reversible fouling, while the reversible and irreversible resistances of the spiral wound membrane averaged 41% and 45%, respectively Cake formation is the model that best represents ultrafiltration in the spiral wound membrane at all transmembrane pressures and cross-flow velocities In the tubular membrane, at the lowest cross-flow velocity (079 ms -1 ), the cake formation model fitted the experimental data best However, at higher cross-flow velocities (142 and 223 ms -1 ), the best fit of flux data was obtained with the complete pore blocking model In addition, the tubular membrane apparently had a two-step pore blocking: “pore blocking” as the initial governing mechanism followed by “cake formation”

Characterization and use of in natura and calcined rice husks for biosorption of heavy metals ions from aqueous effluents

Abstract: Heavy metal removal by adsorption using rice husks as a bioadsorbent was evaluated as an alternative for wastewater treatment. Batch equilibrium experiments and kinetic sorption studies were performed using monocomponent solutions of Ni(II), Cd(II), Zn(II), Pb(II) and Cu(II) in surface samples of in natura(RH) and calcined rice husks (RHA). RHA showed higher potential for removing lead and copper. Experimental data for adsorption isotherms of lead and copper were adjusted by Langmuir, Freundlich and Dubinin-Radushkevick (D-R) models, being better represented by the Langmuir model. The calcination of RH increased its surface area, improving its adsorption properties. From a morphological analysis obtained by SEM and diffraction patterns (XRD), a longitudinal fibrous and amorphous structure was observed for RH. TGA resultsindicated a total mass loss of around 60% for RH and 24.5% for RHA.

Extraction, fatty acid profile and antioxidant activity of sesame extract (Sesamum Indicum L.)

Abstract: This article carried out the extraction of sesame oil by using three extraction techniques: supercritical fluid extraction (SFE), Soxhlet and sequential extraction. The SFE was performed using supercritical carbon dioxide (SC-CO2) as solvent and ethanol as cosolvent. Tests were performed at 20 MPa, 35oC and a flow rate of 2.5 g CO2/min with a total extraction time of 210 minutes. The Soxhlet extraction was performed for 8 hours, using petroleum ether and ethanol as solvents, until the exhaustion of the oil contained in the seeds. The sequential extraction used ethyl ether, ethanol and water as solvents. The Soxhlet extraction was the most effective (58.93%), while the SFE technique obtained 26.47% as the best result. The antioxidant activity (AA) was determined by the β-carotene/linoleic acid system, with good oxidation inhibition percentages (29.32-83.49%) for all the extracts. The main fatty acids (FA) in sesame oil were oleic and linoleic acids.

SYNTHESIS OF A BIOCOPOLYMER CARRAGEENAN-g-POLY(AAm-co-IA)/ MONTMORILONITE SUPERABSORBENT HYDROGEL COMPOSITE

Abstract: A novel superabsorbent hydrogel composite based on kappa-carrageenan (κC) has been prepared via graft copolymerization of acrylamide (AAm) and itaconic acid (IA) monomers in the presence of montmorolonite clay powder, methylenebisacrylamide (MBA) as the crosslinking agent and ammonium persulfate (APS) as initiator. Evidence of grafting and montmorolonite interaction was obtained by comparison of FTIR and TGA spectra of the initial substrates and the superabsorbent composite. A new absorption band at 1722 cm-1 in the composite spectrum confirmed montmorolonite-organic polymer linkages. Moreover, the morphology of the samples was examined by scanning electron microscopy (SEM). The swelling of the superabsorbing hydrogels was also examined in solutions with pH values ranging between 1.0 and 13.0. Finally, the swelling behavior of these composite polymers was investigated in various salt solutions. Results indicated that the swelling capacity decreased with an increase in the ionic strength of the swelling medium. This behavior can be attributed to the charge screening effect of monovalent cations, as well as ionic crosslinking for multivalent cations.

Application of enzymes in leather processing: a comparison between chemical and coenzymatic processes

Abstract: The use of biotechnology by tanneries has increased in recent years. Enzymes can be applied during different steps of the leather production process: soaking, dehairing, bating, dyeing, degreasing or in effluent and solid waste treatment. This study evaluated the performance of five commercial enzymes in soaking and unhairing/liming by comparing the chemical and coenzymatic processes. Tests were conducted in bench drums to evaluate the action of enzymes during each stage. Concentration, processing time and type of enzyme were varied. Total organic carbon and soluble protein were used to measure the efficiency of the processes. Enzymatic activity assays on collagen, keratin and lipid and scanning electron microscopic (SEM) analyses of hides were used to complement the study. Coenzymatic processes generally showed better results in comparison to chemical processes. The enzymes showed activity on all substrates, and the SEM analyses of the hides showed a clear difference between the chemical and coenzymatic processes.

Investigation of asphaltene precipitation in miscible gas injection processes: experimental study and modeling

Abstract: Asphaltene precipitation during natural depletion and miscible gas injection is a common problem in oilfields throughout the world. In this work, static precipitation tests are conducted to investigate the effects of pressure, temperature and gas type and concentration on asphaltene instability. Three different oil samples have been studied under reservoir conditions with/without nitrogen and methane injection. Besides applying common thermodynamic models, a new scaling equation is presented to predict asphaltene precipitation under HPHT gas injection. Extensive published data from the literature are also used in model development. The scaling approach is attractive because it is simple and complex asphaltene properties are not involved in the calculations. Moreover, the proposed model provides universal parameters for different fluid samples over a wide range of pressure and temperature that makes it novel for evaluation of future gas injection projects when simple PVT data are available.

Nanosize MgO as antibacterial agent: preparation and characteristics

Abstract: The antibacterial activity of MgO nanoparticles prepared by a sonication method was evaluated in this paper. The effect of calcination conditions on the size and antibacterial activity of MgO nanoparticles was investigated. MgO nanoparticles were characterized for purity (TGA), crystallinity and crystal size (XRD), particle size and morphology (TEM) and surface area (BET). Results showed that the smallest size of 6 nm could be obtained. The lethal effects of nanocrystalline MgO were evaluated on Lactobacillus plantarum. At a concentration of 100 ppm, the killing effect of MgO was close to 1 log reduction for L. plantarum after 24 h exposure. At 1000 ppm and 24 h exposure, the killing effect of MgO was more than a 2.8 log reduction. With the increase of calcination time, the lethal effect of MgO nanoparticles increased after 6 h or 24 h exposure at 100 ppm or 1000 ppm. 2.86 log and 2.89 log were killed at 1000 ppm after 24 h exposure using the sample MgO, sonication, A, and the sample MgO, sonication, B, respectively. When the sample MgO, sonication, C, was used, the lethal quantity of L. plantarum was increased to a 3.36 log reduction.

Study on fermentation conditions of palm juice vinegar by response surface methodology and development of a kinetic model

Abstract: - Natural vinegar is one of the fermented products which has some potentiality with respect to a nutraceutical standpoint. The present study is an optimization of the fermentation conditions for palm juice vinegar production from palm juice ( Borassus flabellifer) wine, this biochemical process being aided by Acetobacter aceti (NCIM 2251) . The physical parameters of the fermentation conditions such as temperature, pH, and time were investigated by Response Surface Methodology (RSM) with 2 3 factorial central composite designs (CCD). The optimum pH, temperature and time were 5.5, 30 °C and 72 hrs for the highest yield of acetic acid (68.12 g / L). The quadratic model equation had a R 2 value of 0.992. RSM played an important role in elucidating the basic mechanisms in a complex situation, thus providing better process control by maximizing acetic acid production with the respective physical parameters. At the optimized conditions of temperature, pH and time and with the help of mathematical kinetic equations, the Monod specific growth rate (

Extraction of oil and minor lipids from cold-press rapeseed cake with supercritical CO2

Abstract: This study examines the extraction of oil from cold-press rapeseed cake using Supercritical CO2(SC-CO2). The effects of pressure (20, 30, and 40 MPa), temperature (40, 50, and 60 oC), and extraction time (60, 90, and 120 min) on oil yield and composition (tocopherols and carotenoids) were studied using response surface design. The results indicated that pressure influenced the most the yield of oil, followed by temperature and extraction time. Extraction time had no effect on oil composition. Extraction pressure and temperature did not affect the tocopherol concentration of the oil to a great extent, whereas temperature had no affect in its carotenoid concentration. A comparison was made between the relative qualities of oil extracted with SC-CO2at 40 MPa and 60 oC and with n-hexane. Neither solvent affected the unsaponifiable matter content or the composition of phytosterols (mainly β-sitosterol, campesterol and brassicasterol) of the oils, although there was a significant difference (p<0.05) in tocopherol. Extraction with SC-CO2at 40 MPa and 60 oC is recommended to obtain rapeseed-oil enriched with tocopherols and carotenoids as important functional components.

Renewable resources for biosurfactant production by yarrowia lipolytica

Abstract: In this work, the production of a biosurfactant synthesized by Yarrowia lipolytica using different renewable resources as carbon source was investigated. Crude glycerol, a biodiesel co-product, and clarified cashew apple juice (CCAJ), an agroindustrial residue, were applied as feedstocks for the microbial surfactant synthesis. The microorganism was able to grow and produce biosurfactant on CCAJ and crude glycerol, achieving maximum emulsification indexes of 68.0% and 70.2% and maximum variations in surface tension of 18.0 mN.m-1and 22.0 mN.m-1, respectively. Different organic solvents (acetone, ethyl acetate and chloroform - methanol) were tested for biosurfactant extraction. Maximum biosurfactant recovery was obtained with chloroform - methanol (1:1), reaching 6.9 g.L-1for experiments using CCAJ and 7.9 g.L-1for media containing crude glycerol as carbon source.The results herein obtained indicate that CCAJ and the co-product of biodiesel production are appropriate raw materials for biosurfactant production by Y. lipolytica.

Supercritical CO2 extraction of raw propolis and its dry ethanolic extract

Abstract: Three types of propolis extract were prepared and analyzed with respect to their global extraction yields and with respect to the concentration of the following markers: 3,5-diprenyl-4-hydroxycinnamic acid; 3-prenyl-4-hydroxycinnamic acid; 4-hydroxycinnamic acid and 4-methoxy-3,5,7-trihydroxyflavone. The extract EEP (ethanolic extract of propolis) was obtained by the conventional method from raw propolis using ethanol as solvent. The extracts (SFE) were obtained by supercritical solvent extraction from the raw propolis using supercritical carbon dioxide (sc-CO2), with and without the addition of ethanol as a co-solvent. The fractionated supercritical extracts (FSCE) were obtained by fractionation (extract and raffinate) of the dry EEP with sc-CO2. EEP yields of 39.5% were obtained and maximum global extraction yields were 7.3% for SFE with no co-solvent, 51% for SFE with 15% ethanol and 18% for the FSCE extract fraction. The concentrations of the markers in the different extracts differed as a function of the operational parameters, indicating that the addition of co-solvent and the selectivity of sc-CO2 could be manipulated so as to obtain extracts with the yields and concentrations of interest.

Phenolic content, antioxidant activity and antiamylolytic activity of extracts obtained from bioprocessed pineapple and guava wastes

Abstract: The relationship between phenolic content, antioxidant and antiamylolytic activities was investigated in Rhizopus oligosporus-mediated solid-state bioprocessing of pineapple and guava residues. Two different treatments of fruit residues mixed with soy flour (5g of soy flour and 5g of fruit residue; 1g of soy flour and 9g of fruit residue) were inoculated and incubated at 22oC. Phenol rich extracts (non-concentrated and concentrated 10-fold by boiling) from day 2 and 10 were tested for their ability to inhibit alpha-amylase. In order to correlate the enzymatic inhibition with phenolic-linked antioxidant activity of the extracts, samples were evaluated for total phenolic content and free radical scavenging. Alpha-amylase inhibition was observed for all extracts, concentrated or not, with values ranging from 10.91% to 100% (complete inhibition). A direct correlation between the total phenolic content or the free radical scavenging activity and alpha-amylase inhibition was not found, demonstrating that such an inhibition could be caused by the presence of specific compounds, phenolic or not, rather than by the actual concentration of overall fruit phenolics.

Refinery production planning and scheduling: the refining core business

Abstract: Intelligent production planning and scheduling are of paramount importance to ensure refinery profitability, logistic reliability and safety at the local and corporate levels. In Brazil, such activities play a particularly critical role, since the Brazilian downstream model is moving towards a demand-driven model rather than a supply-driven one. Moreover, new and specialized non-linear constraints are continuously being incorporated into these large-scale problems: increases in oil prices implying the need for processing poor quality crudes, increasing demand and new demand patterns for petroleum products, new stringent environmental regulations related to clean fuels and start-up of new production technologies embedded into more complex refining schemes. This paper aims at clarifying the central role of refinery planning and scheduling activities in the Petrobras refining business. Major past and present results are outlined and corporate long-term strategies to deal with present and future challenges are presented.

Media optimization for β-Fructofuranosidase production by Aspergillus oryzae

Abstract: β-Fructofuranosidase production by Aspergillus oryzae IPT301 was maximized in shake flasks. Response Surface Methodology (RSM) involving Small Central Composite Design was adopted to evaluate the fructosyltransferase (FTase) activity by changing three medium component concentrations: sucrose, urea and yeast extract. The optimal set of conditions for maximum fructosyltransferase production was as follows: sucrose 320.5 g/L, urea 7.13 g/L and yeast extract 2.11 g/L. In this optimal condition, the following improvements were achieved: an increase of 48.8% in cell growth, 112% and 62% in micelial and free FTase activities, respectively, 62.8% in the ratio of fructosyltransferase/hydrolytic activities for enzyme linked to mycelium and 67.5% for free enzyme.

Optimization of the immobilization process of β-galatosidade by combined entrapment-cross-linking and the kinetics of lactose hydrolysis

Abstract: The immobilization of Aspergillus oryzae β-galactosidase was achieved by entrapment in sodium alginate and gelatin and cross-linking with glutaraldehyde. The optimal concentrations of the aforementioned variables in the immobilization process were determined using an orthogonal central composite design with an orthogonal axial value of 1.35313. The concentrations of alginate, gelatin and glutaraldehyde that provided the greatest enzymatic activity were 6.60%, 4.05% and 3.64% (w/v), respectively. The stability of the immobilized enzyme under the optimal conditions was evaluated through daily activity assays. After 25 uses, a 20% decrease in the enzymatic activity was observed, indicating that the immobilization process could be used to produce a stable biocatalyst. This study investigates the influence of lactose and product concentrations on kinetic reaction hydrolysis. The concentration ranges for the studied variables were 10 to 56 g/L for lactose and 0 to 11.5 g/L for glucose and galactose. Only galactose presented a competitive inhibitory effect.

Effect of quinoa and potato flours on the thermomechanical and breadmaking properties ofwheat flour

Abstract: The thermomechanical properties of dough and the physical characteristics of bread from quinoa-wheat and potato-wheat composite flours at 10 and 20% substitution level were evaluated. The functional properties of flours were measured by the water absorption index (WAI), water solubility index (WSI) and swelling power (SP). The thermomechanical properties of wheat and composite flours were assessed using a Mixolab and the baking quality characteristics of breads were weight, height, width, and specific volume. The results showed that the higher values of WAI (4.48), WSI (7.45%), and SP (4.84) were for potato flour. The quinoa-wheat composite flour presented lower setback and cooking stability data, which are a good indicator of shelf life of bread. On the other hand, the potato-wheat composite flour showed lower stability, minimum torque and peak torque, and higher water absorption. Weight, height, width, and specific volume of wheat bread were most similar to samples of potato-wheat composite flour at 10% substitution level.

The viscosity distribution around a rising bubble in shear-thinning non-newtonian fluids

Abstract: The viscosity distribution of the liquid around a rising bubble in carboxymethyl cellulose (CMC) aqueous solutions was measured experimentally by particle image velocimetry (PIV). The effect of the concentration of CMC solutions on the viscosity distribution around a bubble and the coupling relations between the viscosity field, flow field and shear stress field were also studied. Results indicated that the specific viscosity (non-dimensionalized by η0) decreases with the increase in CMC solution concentration due to a shear thinning effect. Within the experimental range, similar viscosity distributions of liquids around a rising bubble were found: a hollow cylindrical low viscosity region around the bubble wake and a high viscosity region in the central bubble wake.

Physico-chemical, spectroscopical and thermal characterization of biodiesel obtained by enzymatic route as a tool to select the most efficient immobilized lipase

Abstract: Two microbial lipases from Burkholderia cepacia and Pseudomonas fluorescens were evaluated as catalysts for the enzymatic transesterification of beef tallow with ethanol and the most efficient lipase source was selected by taking into account the properties of the product to be used as fuel. Both lipases were immobilized on an epoxy silica-polyvinyl alcohol composite by covalent immobilization and used to perform the reactions under the following operational conditions: beef tallow-to-ethanol molar ratio of 1:9, 45oC and 400 units of enzymatic activity per gram of fat. Products, characterized using Fourier Transform Infrared spectroscopy (FTIR), viscosimetry, thermogravimetry and 1H NMR spectroscopy, suggested that the biodiesel sample obtained in the reaction catalyzed by Burkholderia cepacia lipase has the best set of properties for fuel usage.

Ex-situ bioremediation of Brazilian soil contaminated with plasticizers process wastes

Abstract: The aim of this research was to evaluate the bioremediation of a soil contaminated with wastes from a plasticizers industry, located in Sao Paulo, Brazil. A 100-kg soil sample containing alcohols, adipates and phthalates was treated in an aerobic slurry-phase reactor using indigenous and acclimated microorganisms from the sludge of a wastewater treatment plant of the plasticizers industry (11gVSS kg-1 dry soil), during 120 days. The soil pH and temperature were not corrected during bioremediation; soil humidity was corrected weekly to maintain 40%. The biodegradation of the pollutants followed first-order kinetics; the removal efficiencies were above 61% and, among the analyzed plasticizers, adipate was removed to below the detection limit. Biological molecular analysis during bioremediation revealed a significant change in the dominant populations initially present in the reactor.

Phenol removal from wastewaters by electrochemical oxidation using boron doped diamond (BDD) and Ti/Ti0.7Ru0.3O2 dsa® electrodes

Abstract: Industrial wastewater containing non-biodegradable organic pollutants consists of highly toxic effluents whose treatment is necessary due to environmental and economical restrictions. In order to treat these effluents, an electrochemical process using a dimensionally stable anode (DSA®) and boron-doped diamond (BDD) electrode was studied. The performance of these electrodes for COD removal from aqueous phenol solution was evaluated in the absence and presence of different chloride concentrations. The results showed that DSA®could be successfully used to remove COD when high chloride concentration (3035 mg L-1 Cl-) and mild current density are employed (50 mA cm-2). On the other hand, the presence of chloride did not have the same significant effect on the COD depletion rate using BDD; however, under mild conditions (50 mA cm-2, 0.190 m s-1), the addition of 607 mg L-1 Cl- improved the COD removal by approximately 52% after 8 hours of electrolysis. The effect of current density (i) and flow velocity (v) were also studied, and it was verified that they have an important role on the process performance, especially when DSA® is used.

Wall effects on the cross-buoyancy around a square cylinder in the steady regime

Abstract: The effects of blockage ratio on the combined free and forced convection from a long heated square obstacle confined in a horizontal channel are investigated in this work. The numerical computations are performed in the steady regime for Reynolds number = 1 - 30, Richardson number = 0 - 1 for blockage ratios of 0.125 and 0.25 for the fixed Prandtl number of 0.7 (air). The governing equations, along with appropriate boundary conditions, are solved by using a semi-explicit finite volume method implemented on the collocated grid arrangement. The total drag and lift coefficients, local and average Nusselt numbers and the representative streamline, vorticity and isotherm patterns are presented to elucidate the role of blockage ratio on the cross-buoyancy across a confined square cylinder. The asymmetry in the flow and temperature fields decreases with increasing value of the blockage ratio. Similar to forced convection, the total drag coefficient increases with increasing value of the blockage ratio for the fixed values of the Reynolds and Richardson numbers.

PRODUCTION OF BIOEMULSIFIERS BY Yarrowia lipolytica IN SEA WATER USING DIESEL OIL AS THE CARBON SOURCE

Abstract: The objective of this work was to investigate, on a flask scale, the production of bioemulsifiers by Yarrowia lipolytica in the presence of sea water, supplemented with nitrogen and phosphate sources, using diesel oil as substrate. A full 24 factorial design was conducted to investigate the effects and interactions of the nutrient concentrations (diesel oil, urea, ammonium sulfate and monobasic potassium phosphate) on the response variables: emulsification activity and surface tension of the cell-free cultures. High emulsification activities (> 5,4 UEA) were determined after 168 h in all the experiments. The interactions among diesel oil, urea and monobasic potassium phosphate favored the emulsification with statistical significance. A correlation between the increase of emulsification activity and the reduction of surface tension was not identified.

Organophilic bentonites based on argentinean and Brazilian bentonites: Part 1: influence of intrinsic properties of sodium bentonites on the final properties of organophilic bentonites prepared by solid-liquid and semisolid reactions

Abstract: This study describes the influence of the intrinsic properties of raw materials on the organophilization of bentonites from Argentinean raw sodium bentonites and Brazilian sodium activated bentonites. The organophilization was done with two methodologies: solid-liquid and semisolid reactions. Correlations between the properties of sodium and organophilic bentonites were established. The effectiveness of the treatments was verified by X-ray diffraction, swelling capacity in water and xylene and SEM to evaluate the morphology of the particles. The analysis was done before and after the modification process. The bentonites had organic cations intercalated, as shown by the increase of the basal spacings, and the organophilic character was confirmed because the bentonites showed xylene swelling capacity and particles with an expanded aspect in comparison to those of the sodium bentonites. Both methodologies were efficient to obtain organophilic clays. The organophilic bentonites obtained from raw sodium bentonites gave better results.

Cachaça distillation investigated on the basis of model systems

Abstract: This work reports experimental tests using commercial spirits that were diluted and had their initial composition modified in order to better measure the distillation behavior of selected minor compounds of importance for the quality of alcoholic beverages. Such compounds were added to the commercial cachaca and the corresponding model wine, obtained after the spirits' dilution, was distilled. In this way a more precise distillation profile could be determined for those minor compounds. The alembic heating was performed by electrical resistance and the corresponding heat transfer coefficient was determined by analyzing the thermal behavior of the still during the distillations. A simulation algorithm was developed, including the mass and enthalpy balances as well as the heat transfer flux to the boiling wine. Good agreement between experimental and simulated results was obtained for the distillate rate, alcoholic graduation, temperature and most minor component profiles.

Drying kinetics, structural characteristics and vitamin C retention of dedo-de-moça pepper (Capsicum baccatum) during convective and freeze drying

Abstract: The main objective of this study was to evaluate the effect of the drying process on the vitamin C levels and physical properties of dedo-de-moca pepper. The drying kinetics and the structural properties were determined as a function of moisture content. Convective drying was compared with freeze-drying in terms of product quality, structural properties, retention of vitamin C and rehydration characteristics. Empirical and semi-empirical equations were used to describe the drying and rehydration kinetics. Nonlinear analysis applied to results of convective drying, based on curvature measures and bias measures, showed that the only equation that gives good inference results based on least squares estimators is the Overhults equation. The characterization of the rehydration process was done by determining the indexes that take into account the water absorption capacity and solutes losses. The material dried by lyophilization show greater potential to rehydrate.