Antonio J. A. Meirelles

Partitioning of whey proteins, bovine serum albumin and porcine insulin in aqueous two-phase systems.

Partitioning of the proteins from cheese whey, bovine serum albumin and porcine insulin were analysed using aqueous two-phase systems (ATPS) prepared with PEG-phosphate, PEG-citrate and PEG-maltodextrin (MD). Proteins were quantified through one of the following methods: FPLC, Bradford and spectrophotometry at 280 nm. Results showed that whey proteins partitioned unevenly on the phases of the systems used, with alpha-lactoalbumin (alpha-La) concentrated in the upper phase and beta-lactoglobulin (beta-Lg) in the lower. Albumin in PEG-MD systems concentrated in the MD-rich lower phase. Porcine insulin showed great affinity with the PEG-rich phase, its partition coefficient was always over 10 and increases with PEG molecular mass.

Partitioning of pectinolytic enzymes in polyethylene glycol/potassium phosphate aqueous two-phase systems

Abstract Four different pectinolytic enzymes have been partitioned in polyethylene glycol (PEG)-potassium phosphate aqueous two-phase systems (20–15%). The influence of PEG molecular weight and the addition of sodium chloride were investigated. The best results concerning to the partition coefficients (Kp and Ke) and the yield recovery (R) were: PEG-400/phosphate with NaCl for exo-polygalacturonase (Ke=5.35 and R=89.5%), PEG-600/phosphate for pectin lyase (PL) (Ke=43.18 and R=98.5%) and pectinesterase (PE) (Ke=1.51 and R=69.6%), and PEG-10,000/phosphate for endo-polygalacturonase (Ke=1.35 and R=53.5%). The best purification factors were observed in the upper phase for the systems containing high molecular weight PEG without NaCl: PEG-6000 for exo-polygalacturonase (5.49 fold) and PEG-10,000 for endo-polygalacturonase (16.28 fold), PE (16.64 fold) and PL (14.27 fold).

The solid-liquid phase diagrams of binary mixtures of consecutive, even saturated fatty acids

For the first time, the solid-liquid phase diagrams of five binary mixtures of saturated fatty acids are here presented. These mixtures are formed of caprylic acid (C(8:0))+capric acid (C(10:0)), capric acid (C(10:0))+lauric acid (C(12:0)), lauric acid (C(12:0))+myristic acid (C(14:0)), myristic acid (C(14:0))+palmitic acid (C(16:0)) and palmitic acid (C(16:0))+stearic acid (C(18:0)). The information used in these phase diagrams was obtained by differential scanning calorimetry (DSC), X-ray diffraction (XRD), FT-Raman spectrometry and polarized light microscopy, aiming at a complete understanding of the phase diagrams of the fatty acid mixtures. All of the phase diagrams reported here presented the same global behavior and it was shown that this was far more complex than previously imagined. They presented not only peritectic and eutectic reactions, but also metatectic reactions, due to solid-solid phase transitions common in fatty acids and regions of solid solution not previously reported. This work contributes to the elucidation of the phase behavior of these important biochemical molecules, with implications in various industrial applications.

The solid-liquid phase diagrams of binary mixtures of consecutive, even saturated fatty acids: differing by four carbon atoms

The complete solid-liquid phase diagrams for four binary mixtures of saturated fatty acids are presented, for the first time, in this work. These mixtures are formed by caprylic acid (C(8:0))+lauric acid (C(12:0)), capric acid (C(10:0))+myristic acid (C(14:0)), lauric acid (C(12:0))+palmitic acid (C(16:0)) and myristic acid (C(14:0))+stearic acid (C(18:0)). The phase diagrams were obtained by differential scanning calorimetry (DSC) and X-ray diffraction (XRD). FT-Raman spectrometry and polarized light microscopy were used to complement the characterization for a complete understanding of the phase diagram. All of the phase diagrams here reported show the same global behavior that is far more complex than previously accepted. They present not only peritectic and eutectic reactions, but also metatectic reactions, due to solid-solid phase transitions common in fatty acids, and regions of solid solution not previously reported. This work contributes to the elucidation of the phase behavior of these important biochemical molecules with implications in various industrial applications.

Water Activity, pH and Density of Aqueous Amino Acids Solutions

The water activity, pH and density of some aqueous amino acid solutions were determined at 25 °C in three different types of solvents. Previous published experimental data on water activity and solubility of amino acids in aqueous solutions were used together with data from this work to test the applicability of a group contribution model. The activity coefficients were estimated by the UNIFAC‐Larsen model combined with the Debye‐Hückel equation, taking also into account the partial dissociation phenomena of species in solution. Interaction energies between the charged species Na+ and Cl− and the specific groups of amino acids (COOH and NH2) were adjusted using experimental solubility data.

Deacidification of Vegetable Oils by Solvent Extraction

The refining of edible oils requires a series of purification steps, with the most important being the decrease of the free fatty acid level of the crude oil. This step is very important for the quality of the final product and has a major impact on the economic feasibility of the whole process. Several techniques, alternative to the conventional caustic or steam distillation methods, are suggested in the literature, such as supercritical extraction, membrane technology and solvent extraction. In the present paper we discuss the main aspects related to the solvent extraction technique, coupled or not with the conventional methods. The reviewed patents indicate various advantages of a purification process based on the selective extraction of free fatty acids using short chain alcohols. Its technical feasibility is due to the differences in solubility of free fatty acids and neutral oil in the proposed solvents. This alternative technique does not generate waste products and can preserve nutraceutical compounds in the refined oil.

Recovery of aroma compounds from orange essential oil

The objective of this work was to study the recovery of aroma compounds present in the orange essential oil using experimental data from CUTRALE (a Brazilian Industry of Concentrated Orange Juice). The intention was to reproduce the industrial unit and afterwards to optimize the recovery of aroma compounds from orange essential oil by liquid-liquid extraction. The orange oil deterpenation was simulated using the commercial software PRO/II 4.0 version 1.0. The UNIFAC model was chosen for the calculation of the activity coefficients.

LLE experimental data, thermodynamic modeling and sensitivity analysis in the ethyl biodiesel from macauba pulp oil settling step.

The aim of this study was to obtain experimental data related to liquid–liquid equilibrium (LLE) of systems containing glycerol + ethanol + ethyl biodiesel from macauba pulp oil, perform thermodynamic modeling and simulate the settling step of this biodiesel using simulation software. Binary interaction parameters were adjusted for NRTL and UNIQUAC models. The UNIFAC-LLE and UNIFAC-Dortmund models were used to predict the LLE of the systems. A sensitivity analysis was applied to the settling step to describe the composition of the output streams as a function of ethanol in the feed stream. Ethanol had greater affinity for the glycerol-rich phase. The deviations between experimental data and calculated values were 0.44%, 1.07%, 3.52% and 2.82%, respectively, using the NRTL, UNIQUAC, UNIFAC-LLE and UNIFAC-Dortmund models. Excess ethanol in the feed stream causes losses of ethyl ester in the glycerol-rich stream and high concentration of glycerol in the ester-rich stream.

Computational simulation applied to the investigation of industrial plants for bioethanol distillation

This work aimed to investigate a typical bioethanol distillation process considering an alcoholic wine with 19 components and to validate the simulation results against experimental data collected from a Brazilian sugar mill. The process was investigated in terms of bioethanol alcoholic graduation, ethanol recovery, energy consumption and ethanol loss. Two optimizing approaches were tested: the central composite design (CCD) and the sequential quadratic programming (SQP). Both approaches allowed the optimization of the equipment configuration used nowadays and provided similar optimal conditions. The results showed that the simulation approach was capable of correctly reproducing a real plant of bioethanol distillation and that the optimal conditions guaranteed the bioethanol production according to legislation, with low consumption of steam and high recovery of ethanol. On the other hand, substantial fluctuations in wine composition may require adjustments of operational conditions or the use of specific control loops to prevent an off-specification product.

Technology gap, real wages, and learning in a balance-of-payments---constrained growth model

This paper argues that in developing countries, higher real wages---up to a certain critical point---may enhance the ability of workers to learn from and improve on foreign technology, with positive effects on international competitiveness and on the rate of economic growth consistent with current account equilibrium. Countries whose institutions severely hamper the increase in real wages could be trapped in a low-wage, slow-growth equilibrium. But learning opportunities derived from higher real wages are not boundless. Policies aimed at improving income distribution should be complemented by policies aimed at fostering the international diffusion of technology in order to sustain economic growth in the long run. These interactions between real wages and learning are studied within the context of a balance-of-payments---constrained growth model including two countries (North and South) with different levels of technological development.