Rafael da Costa Ilhéu Fontan

Density and Dynamic Viscosity of Bovine Milk Affect by Temperature and Composition

In order to design and to adapt equipments for food processing, it is essential to know thermophysical properties. Once temperature and composition affects these properties, models based in such factors are important for further calculation. In this work, density and dynamic viscosity of bovine milk, probably the most processed food fluid in the world, were determined within large ranges of temperature and major constituents (moisture, fat, lactose, protein and minerals), based on typical processing values. Density varied from (962.01 to 1100.45) kg/m3 and dynamic viscosity varied from (0.60 to 63.70) mPa∙s. Temperature and moisture content negatively affected both properties, while lactose, protein and minerals contents positively affected them. An increase in fat content reduced density and increased dynamic viscosity. Experimental density data were fitted to the simplest multiple linear model and dynamic viscosity data were fitted to a multiple type Arrehnius’ model, obtaining good agreement.

Gelatinization temperature and acid resistance of jackfruit seed starch.

The objectives of this work were to determine the gelatinization temperature of jackfruit starch and to compare the effect of pH on the viscosity and density of different botanical sources of starch pastes. The study was conducted according to a three × four factorial design with three repetitions, being three levels for the starch paste (jackfruit seed, corn and cassava) and four levels for pH (3.4; 4.4; 5.4 and 7.0). The results showed a gelatinization temperature (GT) of jackfruit seed starch ranging from 75 to 80 °C, superior to GT range of common starch sources. Density of all starch pastes increased with pH. The effect of the kind of starch was not significant (P > 0.05). Viscosity of corn and cassava starch pastes varied with pH according to quadratic models. The viscosity of seed starch paste from jackfruit did not significantly vary with pH, indicating acid resistance.

Preparation of an affinity cryogel column for lysozyme purification

ABSTRACT Affinity cryogels were synthesized using tris(hydroxymethyl)aminomethane (Tris) as ligand for specific interactions with the lysozyme (LYZ). The cryogel was produced by cryo-copolymerization at −12°C. A central composite rotational design 22 was used to optimize the immobilization procedure of the Tris on the cryogel. A maximum adsorption for LYZ (149.5 mg/g) was achieved when 376 mg/mL of Tris and 3.06 mol/L of sodium borohydride were used during the Tris immobilization. Chromatographic separation of LYZ from chicken egg white was done with a purity of 92.13%. Results showed that the affinity cryogel was a potential separation medium for LYZ purification.

Effect of the incorporation of lysozyme on the properties of jackfruit starch films

AbstractJackfruit starch based biodegradable films containing lysozyme were characterized for their antimicrobial activity, thickness, solubility, water vapor permeability and mechanical properties. The biodegradable films had good appearance and antimicrobial activity against Micrococcus lysodeikticus. The thickness of the biodegradable films were not affected by the variation in pH, but the addition of lysozyme increased the thickness, the thickest films being those with the highest lysozyme concentrations. The variation in pH of the filmogenic solutions affected the solubility of the biodegradable films, water solubility being greatest at pH 7.0 and with the highest lysozyme concentration. The permeability of the biodegradable films was increased by incorporating lysozyme. The lysozyme concentration and pH variation caused changes in the mechanical properties. The addition of 8% lysozyme increased the tensile strength and Young’s modulus for all the pH values studied. With respect to the release of antimicrobial activity, the diffusion of lysozyme was shown to follow Fickian transport mechanism.

The Impact of Heat-moisture Treatment on Properties of Musa paradisiaca L. Starch, and Optimization of Process Variables

SUMMARY Starch stability under the processing conditions can be improved by modifying the granule structure using chemical and/or physical processes. The effect of heat-moisture treatment (HMT) on the physicochemical, morphological, pasting and thermal properties of green banana (Musa paradisiaca L.) starch was investigated. To analyze the changes in starch properties due to the combined effect of the process variables, time (h), moisture (%), and temperature (°C) were considered as independent variables using a central composite rotatable design. The native starch extracted using ammonium hydroxide as an antioxidant contained 80.4% total carbohydrates, 53.7% apparent amylose, 11.46% moisture, and other constituents (ash, protein, lipids), which accounted for less than 1%. The granule morphology was affected by the moisture and temperature used in HMT. A and B type X-ray diffraction patterns were observed in the native and modified starch. Mathematical models that describe the behaviour of modified starch properties as a function of the evaluated parameters were obtained. The variables time and temperature significantly affected the physicochemical, rheological and digestibility properties of starch.

Immobilization of sugars in supermacroporous cryogels for the purification of lectins by affinity chromatography

Lectins are glycoproteins that bind to carbohydrates or glycoconjugates by specific interactions. The specificity of lectins to various carbohydrates is a determinant factor in the choice of ligand for the chromatographic matrix when using chromatography as a lectin purification technique. In this work, the immobilization of three different aminated carbohydrates on the surface of macroporous polymeric cryogels was evaluated. Carbohydrates were immobilized on cryogel surfaces via the glutaraldehyde method to create spacer arms, reducing steric hindrance. The immobilized N-acetyl-d-glucosamine and N-acetyl-d-mannosamine concentrations contained approximately 130mg of carbohydrate/g dehydrated cryogel, while the N-acetyl-d-galactosamine contained 105mg of carbohydrate/g dehydrated cryogel. Scanning electron microscopy showed that the physical structure and porosity of the chromatographic columns were not affected by the immobilization process, maintaining an elevated hydration capacity and the macroporous structure of the cryogels. Adsorption of concanavalin A on cryogels functionalized with N-acetyl-d-glucosamine (cryo-d-GlcNAc) was tested, as well as its reuse capability. After 5 cycles of use, cryo-d-GlcNAc was shown to be stable, with an adsorptive capacity of around 50mg/g. Carbohydrate immobilization in polyacrylamide cryogels was satisfactory, with promise for applications in lectin purification processes.

Partitioning Behavior of Lysozyme and α-lactalbumin in Aqueous Two-Phase System Formed by Ionic Liquids and Potassium Phosphate

Abstract Nowadays ionic liquids (ILs), because of their “green” characteristics, have been used for analytical and separation processes. Therefore the partitioning of lysozyme and α-lactalbumin using aqueous two-phase systems (ATPSs) composed of an ionic liquid (chloride 1-ethyl-3-methylimidazolium) and inorganic salts (K2HPO4, KH2PO4) was studied. Phase equilibrium diagrams were obtained to explore the effect of the different temperatures (293.15, 303.15, 313.15, and 323.15) K and pH (7.5, 8.0, and 8.5) used for the partitioning studies. For both proteins, partition coefficients decreased with increasing temperature. The pH influenced the partition coefficients of lysozyme and α-lactalbumin. The thermodynamic parameters (ΔH◦, ΔS◦, ΔG◦) indicate thermodynamic differences between the partitioning of lysozyme and α-lactalbumin in this system. The ΔH◦, ΔS◦, and ΔG◦ values of the process studied showed that this process is spontaneous. This work demonstrates the possible use of ATPSs with ILs and inorganic salts as a methodology for the partitioning of lysozyme and α-lactalbumin.

OBTENÇÃO DE DADOS DE EQUILÍBRIO DE SISTEMAS AQUOSOS BIFÁSICOS FORMADOS POR POLIETILENOGLICOL E FOSFATO DE POTÁSSIO

RESUMO A extracao liquido-liquido utilizando sistemas aquosos bifasicos (SABs) e uma tecnica promissora na purificacao de biomoleculas de interesse industrial e laboratorial. Para a purificacao de compostos utilizando SABs e imprescindivel a obtencao dos dados de equilibrio nas condicoes de particao. Diante disso, objetivou-se nesse trabalho a construcao das binodais para sistemas aquosos bifasicos compostos por polietilenoglicol 6000 g.mol -1 (PEG 6000), fosfato de potassio e agua, nos pHs 6 e 7, na temperatura de 5°C. O efeito do pH nas curvas binodais foi analisado, sendo observado uma diminuicao da area bifasica com a diminuicao do pH. Verificou-se ainda que a elevacao do pH aumentou o comprimento da linha de amarracao (CLA), e diminuiu a inclinacao (ILA). Foi possivel a obtencao dos dados de equilibrio do sistema PEG/fosfato nas condicoes estudadas.

OBTENÇÃO DE DADOS DE EQUILÍBRIO DE SISTEMAS AQUOSOS BIFÁSICOS FORMADOS POR POLIETILENOGLICOL E LÍQUIDO IÔNICO

RESUMO A busca crescente por processos seguros e eficazes de separacao para materiais biologicos aliado as propriedades vantajosas do polietileno glicol (PEG) e liquidos ionicos (LI), levaram a aplicacoes promissoras e atraentes dos novos sistemas aquosos bifasicos. Diante disso, objetivou-se nesse trabalho a construcao das binodais para sistemas aquosos bifasicos compostos por polietilenoglicol (PEG), liquido ionico (cloreto de 1-etil-3-metilimidazolio) e agua. Os polimeros utilizados de diferentes massas molares foram PEG 1500 g.mol -1 e PEG 4000 g.mol -1 . Os sistemas PEG 1500 + liquido ionico e PEG 4000 + liquido ionico foram analisados nas temperaturas de (20 e 50) °C. O efeito da temperatura nas curvas binodais foi analisado tendo em vista os dois tipos de PEG utilizados, sendo observado uma diminuicao da area bifasica com o aumento da temperatura para ambos os sistemas utilizados. O efeito da massa molar tambem foi estudado, verificando um aumento da area bifasica nos sistemas com o PEG de maior massa molar.

ESTUDO DO PROCESSO DE ADSORÇÃO DE AZUL DE METILENO EM MEIO AQUOSO EMPREGANDO SILICA SBA-15 COMO ADSORVENTE

A silica SBA-15 e um material mesoporoso com grande potencial de aplicacao, inclusive no processo de adsorcao. Levando esse fator em consideracao objetivou-se nesse trabalho sintetizar e caracterizar a silica SBA-15 nas temperaturas de 80°C, 105°C e 120°C e estudar a sua capacidade de adsorcao do corante azul de metileno em meio aquoso em diferentes condicoes de concentracao e pH. Foi verificado que a silica sintetizada na temperatura de 80°C apresentou maior eficiencia de adsorcao. Tal fato pode ser explicado pela maior area superficial dessa silica, apresentando assim mais sitios de ligacao, favorecendo a adsorcao. A combinacao que obteve uma maior adsorcao no teste inicial foi a silica sintetizada a 80°C com o azul de metileno na concentracao de 100 mg.L -1 . Posteriormente, foi verificado que o pH 9,0 foi o que obteve a maior eficiencia de adsorcao.