Partitioning of glycomacropeptide in aqueous two-phase systems

The partition behavior of glycomacropeptide (GMP) was determined in polyethylene glycol (PEG) and sodium citrate aqueous two-phase systems (ATPS). It was found that the partitioning of GMP depends on PEG molar mass, tie line length, pH, NaCl concentration and temperature. The obtained data indicates that GMP is preferentially partitioned into the PEG phase without addition of NaCl at pH 8.0. Larger tie line lengths and higher temperatures favor GMP partition to the PEG phase. Furthermore, it was verified that PEG molar mass and concentration have a slight effect on GMP partition. The increase in the molar mass of PEG induces a reduction of the protein solubility in the top PEG rich phase, being shown that the use of PEG1500 is beneficial for the extraction of GMP. A protein recovery higher than 85% was obtained in the top phase of these systems, clearly demonstrating its suitability as a starting point for the separation of GMP.Research Support Foundation of Minas Gerais (FAPEMIG)National Council of Technological and Scientific Development (CNPq

Optimization of the ultrasonic treatment for Tara gum using response surface methodology

Abstract High-intensity ultrasound irradiation proved to be an effective method for modifying tara gum by generating low molecular weight products and better water solubility. The objectives of this research were to optimize the parameters for the high-intensity ultrasonic treatment with response surface methodology and improve the tara gum solubility. The results demonstrated that after the ultrasound treatment, the solubility of the tara gum had increased (17.7%) as a result of the reduced intrinsic viscosity (70%). The molecular weight of the untreated tara gum was 1.89 x 106 Da, and after ultrasound treatment, it was reduced to 0.47 x 106 Da. Rheological analyses confirmed the reduction in molecular weight for the modified and optimized tara gum and the resulting increase in solubility. This knowledge provides a better understanding of ultrasound treatment technology and increases the scope for use of tara gum in the food industry

Density, refractive index, apparent specific volume, and electrical conductivity of aqueous solutions of poly(ethylene glycol) 1500 at different temperatures

Thermophysical properties of aqueous solutions of poly(ethylene glycol) 1500 g·mol–1 were measured as a function of polymer concentration w=(0.05, 0.10, 0.15, 0.20 and 0.25) and temperature T/K=(288, 293, 298, 303 and 308). Aqueous systems composed of poly(ethylene glycol) are frequently used in processes involving the separation of biological compounds. The density of the solutions varied from (1001.68 to 1042.65) kg·m–3, the refractive index ranged from (1.3377 to 1.3681), the apparent specific volume was between (0.8336 and 0.8528) g·cm–3, and the electrical conductivity varied between (66.22 and 170.29) 10–3 mS·cm–1. Polynomial models for the properties as a function of temperature and poly(ethylene glycol) 1500 g·mol–1 concentration were fitted to the experimental data. Models accounting for combined effects between variables are particularly useful in industrial applications in which physical parameters must be promptly and accurately calculated.We are thankful to the Brazilian agencies CAPES, CNPq, FAPEMIG, and FAPESP for the financial support, fellowships, and grants

REVISÃO: TÉCNICAS USADAS NO PROCESSO DE PURIFICAÇÃO DE BIOMOLÉCULAS

A presente revisão da literatura teve por objetivo mostrar as diferentes técnicas que podem ser empregadas no processo de purificação de biomoléculas. Além da seleção e combinação de técnicas de separação para o desenvolvimento da estratégia de purificação foram abordadas a precipitação, a centrifugação, a tecnologia de membranas (osmose reversa, ultrafiltração, diálise e microfiltração), a extração líquido-líquido usando sistemas aquosos bifásicos, as técnicas cromatográficas (troca iônica, interação hidrofóbica, fase reversa, exclusão molecular, leito expandido), as separações biosseletivas (cromatografia por afinidade, precipitação por afinidade, partição de proteínas por afinidade em sistemas aquosos bifásicos) e novas técnicas de separação (leito móvel simulado, micelas reversas e cromatografia em contracorrente). Verificou-se que as técnicas cromatográficas estão presentes em todos os processos de purificação de biomoléculas, embora ainda existam restrições técnicas e econômicas na aplicação de alguns tipos de cromatografia em escala preparativa. REVIEW: TECHNIQUES UTILIZED IN BIOMOLECULES PURIFICATION PROCESS Abstract The present literature review had as objective to show the different techniques that may be employed in biomolecules purification process. Besides selection and combination of separation techniques for the development of a purification strategy, precipitation, centrifugation, membrane technology (reverse osmose, ultrafiltration, dialysis and microfiltration), liquid-liquid extraction employing two phase aqueous systems, chromatography techniques (ion exchange, hidrophobic interactions, reverse phase, molecular exclusion, expanded bed), bio-selective separations (affinity chromatography, affinity precipitation, protein partition by affinity in two-phase aqueous system) and new separation techniques (simulated moving bed, reverse micelles, counter-current chromatography) was abborded. It was verified that chromatographic techniques are present in all biomolecules purification processes, although there are technical and economical restrictions in the application of some types of chromatography in preparative scale

Separation techniques applied to the egg processing

Neste trabalho foi avaliado o uso de adsorventes com características hidrofóbicas para a redução do teor de colesterol presente na gema e no plasma da gema de ovo bem como na adsorção das proteínas lisozima, conalbumina e ovalbumina da clara. O gel de pectina de alto teor de grupos metoxila foi um dos tipos de adsorvente empregado na redução de teor de colesterol da gema de ovo líquida in natura. Os experimentos com gel de pectina foram planejados utilizando a metodologia de superfície de resposta, com vistas a definir o nível de máxima extração de colesterol para um mínimo decréscimo do conteúdo protéico da gema. Foi observada, na gema, uma redução de 85,6% no teor de colesterol e uma queda de 11,4% no conteúdo protéico. A resina Streamline Phenyl® foi o outro tipo de adsorvente usado no estudo da redução do teor de colesterol presente no plasma da gema. Para tanto foram obtidos dados de equilíbrio de adsorção hidrofóbica do colesterol em tanques agitados à 25 ± 2°C. Observou-se que o aumento da concentração de sal (NaCl e Na2SO4) no sistema reduziu a extração de colesterol pela resina. Também foi constatado a redução de 70% do teor de colesterol com o uso de uma relação de diluição plasma:água de 1:4. Essa mesma resina foi empregada na adsorção hidrofóbica das proteínas da clara do ovo lisozima, conalbumina e ovalbumina, em tanques agitados a 25 ± 2°C. Verificou-se o aumento da retenção das proteínas com a elevação da concentração de sal nos sistemas. Entre os diferentes tipos de sais estudados (NaCl, Na2SO4 e (NH4)2SO4) foi observada uma maior extração das proteínas com o uso de Na2SO4, indicando assim que este tipo de sal apresentou maior interação com as proteínas avaliadas, embora cada tipo de sal interaja em grau diferenciado com cada uma das proteínas. O modelo de transferência de massa empregado simulou corretamente o comportamento da cinética de adsorção das proteínas nas condições estudadas.Hydrophobic adsorbents were used to evaluate the cholesterol content reduction in egg yolk and plasma of egg yolk, and also the purification of egg white proteins lysozyme, conalbumin and ovalbumin. The gel of high methoxyl pectin was one kind of adsorbent tested aiming the reduction of the liquid egg yolk cholesterol. The response surface methodology was applied to define the level of maximum yolk cholesterol removal at a minimum yolk protein extraction. The optimal values were of 85,6% for the cholesterol content reduction and of 11,4% for the protein content decrease. The Streamline Phenyl® resin was the other kind of hydrophobic adsorbent evaluated in the cholesterol reduction of the plasma of egg yolk. Equilibrium data of cholesterol hydrophobic batch adsorption were determined at room temperature (25 ± 2 °C). The increase of the salt (NaCl and Na2SO4) concentration led to the decrease of the plasma yolk cholesterol adsorption and the increase of the plasma dilution increased the cholesterol extraction. A plasma:water dilution of 1:4 reduced 70% of the plasma cholesterol content. The Streamline Phenyl® resin was also used in the hydrophobic batch adsorption of the egg white proteins lysozyme, conalbumin and ovalbumin, at 25 ± 2°C. It was observed the increase of the protein adsorption on the increase of salt (NaCl, Na2SO4 and (NH4)2SO4) concentration. The model of mass transfer used was appropriate to simulate the kinetics of adsorption of the studied proteins.Conselho Nacional de Desenvolvimento Científico e TecnológicoFundação de Amparo à Pesquisa do Estado de Minas Gerai

Separation and purification of α-lactalbumin and β-lactoglobulin using size exclusion chromatography after aqueous two-phase systems extraction

Neste trabalho, foi utilizada a cromatografia por exclusão molecular (CEM) para purificação das proteínas do soro de queijo α-lactoalbumina (α-la) e β-lactoglobulina (β-lg) presentes, respectivamente, nas fases polimérica e salina de sistemas aquosos bifásicos (SAB), compostos por polietilenoglicol (PEG), água e fosfato de potássio (FFP). As viscosidades das fases foram o parâmetro empregado para selecionar a concentração de soro de queijo a ser adicionada aos SAB. Usando os dados de viscosidade, foi escolhido para estudo o SAB composto por 18% PEG 1500 + 18% FFP + 10% de soro de queijo + 54% água, (%peso/peso). Partindo deste sistema, foram determinadas as melhores condições operacionais para a CEM: 4,0 mL/min de vazão e 0,5 mL de volume de amostra para a fase polimérica e 2,0 mL/min de vazão e 0,5 mL de volume de amostra para a fase salina. Nestas condições, a resolução, a produtividade e o grau de purificação foram, respetivamente, de 1,53, 0,43 mg.(mL.h) -1 e 99,7% para a fase salina e de 1,29, 0,31 mg.(mL.h) -1 e 99,6% para a fase polimérica. A resina que melhor se adequou ao processo de separação foi a Shepadex G-25® médio (50-150) μm. Na modelagem do processo cromatográfico, foi empregado um modelo matemático cosiderando dispersão axial na coluna e difusão radial em cada partícula. Foram calculados os parâmetros de transferência de massa por meio de regressão não linear, utilizando o método de programação quadrática sucessiva. A modelagem levou a resultados satisfatórios descrevendo, adequadamente, o processo cromatográfico de exclusão molecular.Size exclusion chromatography (SEC) was used in this work to purify the cheese whey proteins α-lactalbumin (α-la) and β-lactoglobulin (β-lg) present, respectively, in the polymeric and saline phases of aqueous two phase systems (ATPS), composed by polyethyleneglycol (PEG), water and potassium phosphate (FFP). The phase viscosities where the parameters applied to choose whey proteins concentration to be added into the ATPS. It was selected the ATPS formed by 18% (w/w) PEG 1500 + 18% (w/w) FFP + 10% (w/w) of cheese whey + 54% water. Based on this system, the best operational conditions for SEC were 4,0 mL/min of flow rate and 0,5 mL of sample volume for the polymeric phase and 2,0 mL/min of flow rate and 0,5 mL of sample volume for the saline phase. Under these conditions, resolution, productivity and purification degree were, respectively, of 1.53, 0.43 mg.(mL.h) -1 and 99.7% for the saline phase and 1.29, 0.31 mg.(mL.h) -1 and 99.6% for the polymeric phase. The resin that best fit the purification process was ShepadexG-25® medium (50-150 μm). A mathematical model with axial dispersion in the column and radial diffusion in each particle was used to model the chromatographic process. Mass transfer parameters were calculated by means of non-linear regression, using the successive quadratic programming method. The process was successful describe by the modelConselho Nacional de Desenvolvimento Científico e Tecnológic

Emulsões múltiplas: formação e aplicação em microencapsulamento de componentes bioativos

Emulsões múltiplas têm sido reconhecidas como uma nova tecnologia para as indústrias de alimentos. Devido a sua estrutura diferenciada dos demais sistemas coloidais, ou seja, existência de duas fases dispersas, esse grupo de emulsão apresenta vantagens em relação às emulsões convencionais, principalmente, no que se refere ao encapsulamento, à proteção e à liberação controlada de componentes bioativos. Assim, a estabilidade e a biodisponibilidade dos encapsulados podem ser aumentadas ou otimizadas, fato que possibilita o planejamento de melhores resultados pela indústria, por meio da produção de novos alimentos. Ainda, com a perspectiva de aumentar o valor nutricional de muitos alimentos industrializados, infere-se uma maior contribuição deles para a promoção da saúde e para prevenção e tratamento de certas doenças crônico-degenerativas. A presente revisão apresenta as bases da tecnologia usual de elaboração de emulsão múltipla, os principais processos de instabilidade a que esse sistema está susceptível, e a aplicação de emulsões múltiplas como sistemas encapsuladores e transportadores de componentes bioativos

Textural behavior of gels formed by rice starch and whey protein isolate: Concentration and crosshead velocities

ABSTRACT Fabricated food gels involving the use of hydrocolloids are gaining polpularity as confectionery/convenience foods. Starch is commonly combined with a hydrocolloid (protein our polyssacharides), particularly in the food industry, since native starches generally do not have ideal properties for the preparation of food products. Therefore the texture studies of starch-protein mixtures could provide a new approach in producing starch-based food products, being thus acritical attribute that needs to be carefully adjusted to the consumer liking. This work investigated the texture and rheological properties of mixed gels of different concentrations of rice starch (15%, 17.5%, and 20%) and whey protein isolate (0%, 3%, and 6%) with different crosshead velocities (0.05, 5.0, and 10.0 mm/s) using a Box-Behnken experimental design. The samples were submitted to uniaxial compression tests with 80% deformation in order to determinate the following rheological parameters: Young’s modulus, fracture stress, fracture deformation, recoverable energy, and apparent biaxial elongational viscosity. Gels with a higher rice starch concentration that were submitted to higher test velocities were more rigid and resistant, while the whey protein isolate concentration had little influence on these properties. The gels showed a higher recoverable energy when the crosshead velocity was higher, and the apparent biaxial elongational viscosity was also influenced by this factor. Therefore, mixed gels exhibit different properties depending on the rice starch concentration and crosshead velocity