Interação Entre Xilanase, Glicose Oxidase E ácido Ascórbico Na Qualidade Tecnológica De Pão Elaborado Com Farinha Do Trigo Integral

This study aimed to verify the performance of xylanase and its interaction with oxidants agents (glucose oxidase and ascorbic acid) on the quality of whole wheat bread. The experiment was based on a central composite rotational design and the Response Surface Methodology was used to analyze the results. None of the xylanase, glucose oxidase or ascorbic acid concentrations within the studied range led to a significant difference in the specific volume. The highest moisture content and the lowest firmness values were reported in the bread with lower and intermediate levels of xylanase and larger amounts of glucose oxidase and ascorbic acid. This effect was observed mainly at the end of the storage period. A minimum amount of xylanase (from 33 to 63 EDX kg-1 flour) showed to be essential for obtaining best results. Levels of ascorbic acid above 63mg kg-1 and glucose oxidase above 91 SRU kg-1 proved to be necessary to offer the beneficial effect of xylanase. © 2016, Universidade Federal de Santa Maria. All rights reserved.46122249225

Influence of the biquadratic interlayer coupling in the specific heat of Fibonacci magnetic multilayers

A theoretical study of the specific heat C(T) as a function of temperature in Fibonacci magnetic superlattices is presented. We consider quasiperiodic structures composed of ferromagnetic films, each described by the Heisenberg model, with biquadratic and bilinear coupling between them. We have taken the ratios between the biquadratic and bilinear exchange terms according to experimental data recently measured for different regions of their regime. Although some previous properties of the spin wave specific heat are also reproduced here, new features appear in this case, the most important of them being an interesting broken-symmetry related to the interlayer biquadratic term.Comment: 13 pages, 4 ps figures, Submitted to Physica

Magnetic hyperthermia experiments with magnetic nanoparticles in clarified butter oil and paraffin: A thermodynamic analysis

In specific power absorption models for magnetic fluid hyperthermia (MFH) experiments, the magnetic relaxation time of nanoparticles (NPs) is known to be a fundamental descriptor of the heating mechanisms. The relaxation time is mainly determined by the interplay between the magnetic properties of NPs and the rheological properties of NPs’ environment. Although the role of magnetism in MFH has been extensively studied, the thermal properties of the NP medium and their changes during MFH experiments have been underrated so far. Herein, we show that ZnxFe3-xO4 NPs dispersed through different media with phase transition in the temperature range of experiment as clarified butter oil (CBO) and paraffin. These systems show nonlinear behavior of the heating rate within the temperature range of MFH experiments. For CBO, a fast increase at ~306 K is associated with changes in the viscosity (¿(T)) and specific heat (cp(T)) of the medium at its melting temperature. This increment in the heating rate takes place around 318 K for paraffin. The magnetic and morphological characterization of NPs together with the observed agglomeration of NPs above 306 and 318 K for CBO and paraffin, respectively, indicate that the fast increase in MFH curves could not be associated with the change in the magnetic relaxation mechanism, with Neél relaxation being dominant. In fact, successive experimental runs performed up to temperatures below and above the CBO and paraffin melting points resulted in different MFH curves due to agglomeration of NPs driven by magnetic field inhomogeneity during the experiments. Our results highlight the relevance of the thermodynamic properties of the system NP-medium for an accurate measurement of the heating efficiency for in vitro and in vivo environments, where the thermal properties are largely variable within the temperature window of MFH experiments

Expression of a methionine-rich storage albumin from the Brazil nut (Bertholletia excelsa H.B.K., Lecythidaceae) in transgenic bean plants (Phaseolus vulgaris L., Fabaceae)

Bean (Phaseolus vulgaris), an important component in the diet of people in developing countries, has low levels of the essential amino acid, methionine. We have attempted to correct this deficiency by introducing a transgene coding for a methionine-rich storage albumin from the Brazil nut via biolistic methods. The transgene's coding sequence was driven by a doubled 35S CaMV promoter and AMV enhancer sequences. The transgene was stable and correctly expressed in homozygous R2 to R5 seeds. In two of the five transgenic lines the methionine content was significantly increased (14 and 23%) over the values found in untransformed plants.O feijão (Phaseolus vulgaris L.) é um componente importante na dieta da população de países em desenvolvimento. Entretanto, possui um baixo nível de aminoácidos essenciais, como a metionina. Numa tentativa de corrigir esta deficiência, plantas transgênicas de feijão foram produzidas contendo o gene de uma proteína rica em metionina, a albumina 2S da castanha do Brasil. O gene desta albumina (be2s2), clonado sob o controle do promotor 35S dobrado do vírus do mosaico da couve-flor e uma seqüência "enhancer" do vírus do mosaico da alfafa, foi introduzido em feijão através do processo biobalístico. O gene foi expressado corretamente em sementes homozigotas desde a segunda até a quinta geração. Em duas linhagens transgênicas o nível de metionina foi incrementado em 14 e 23% nas sementes

Adjusting the Neel relaxation time of Fe3O4/ZnxCo1-xFe2O4 core/shell nanoparticles for optimal heat generation in magnetic hyperthermia

In this work it is shown a precise way to optimize the heat generation in high viscosity magnetic colloids, by adjusting the Neel relaxation time in core/shell bimagnetic nanoparticles, for magnetic fluid hyperthermia (MFH) applications. To pursue this goal, Fe3O4/ZnxCo1-xFe2O4 core/shell nanoparticles were synthesized with 8.5 nm mean core diameter, encapsulated in a shell of similar to 1.1 nm of thickness, where the Zn atomic ratio (Zn/(Zn + Co) at%) changes from 33 to 68 at%. The magnetic measurements are consistent with a rigid interface coupling between the core and shell phases, where the effective magnetic anisotropy systematically decreases when the Zn concentration increases, without a significant change of the saturation magnetization. Experiments of MFH of 0.1 wt% of these particles dispersed in water, in Dulbecco modified Eagles minimal essential medium, and a high viscosity butter oil, result in a large specific loss power (SLP), up to 150 W g(-1), when the experiments are performed at 571 kHz and 200 Oe. The SLP was optimized adjusting the shell composition, showing a maximum for intermediate Zn concentration. This study shows a way to maximize the heat generation in viscous media like cytosol, for those biomedical applications that require smaller particle sizes

Effects of Zn Substitution in the Magnetic and Morphological Properties of Fe-Oxide-Based Core-Shell Nanoparticles Produced in a Single Chemical Synthesis

Magnetic, compositional, and morphological properties of Zn-Fe-oxide core-shell bimagnetic nanoparticles were studied for three samples with 0.00, 0.06, and 0.10 Zn/Fe ratios, as obtained from particle-induced X-ray emission analysis. The bimagnetic nanoparticles were produced in a one-step synthesis by the thermal decomposition of the respective acetylacetonates. The nanoparticles present an average particle size between 25 and 30 nm as inferred from transmission electron microscopy (TEM). High-resolution TEM images clearly show core-shell morphology for the particles in all samples. The core is composed by an antiferromagnetic (AFM) phase with a Wüstite (Fe1-yO) structure, whereas the shell is composed by a ZnxFe3-xO4 ferrimagnetic (FiM) spinel phase. Despite the low solubility of Zn in the Wüstite, electron energy-loss spectroscopy analysis indicates that Zn is distributed almost homogeneously in the whole nanoparticle. This result gives information on the formation mechanisms of the particle, indicating that the Wüstite is formed first, and the superficial oxidation results in the FiM ferrite phase with similar Zn concentration than the core. Magnetization and in-field Mössbauer spectroscopy of the Zn-richest nanoparticles indicate that the AFM phase is strongly coupled to the FiM structure of the ferrite shell, resulting in a bias field (HEB) appearing below TNFeO, with HEB values that depend on the core-shell relative proportion. Magnetic characterization also indicates a strong magnetic frustration for the samples with higher Zn concentration, even at low temperatures

In vivo assessment of possible probiotic properties of Zymomonas mobilis in a Wistar rat model

In recent years the incorporation of probiotic bacteria into foods has received increasing scientific interest for health promotion and disease prevention. The safety and probiotic properties of Zymomonas mobilis CP4 (UFPEDA-202) was studied in a Wistar rat model fed the 109 colony forming units (cfu)/mL-1 of the assayed strain for 30 days. No abnormal clinical signs were noted in the group receiving viable cells of Z. mobilis and water (control) during the period of the experiment. There were no significant difference (p > 0.05) in feed intake and weight gain among mice fed the Z. mobilis in comparison to the control group. No bacteria were found in blood, liver and spleen of any animals. Mice receiving Z. mobilis showed significantly differences (p < 0.05) in total and differential leucocytes count, excepting for neutrophils, after the experimental period. Otherwise, it was not found in control group. Histological examination showed that feeding mice with Z. mobilis caused no signs of adverse effects on gut, liver and spleen. From these results, Z. mobilis CP4 (UFEPEDA-202) is likely to be nonpathogenic and safe for consumption, and could have a slight modulating effect on immunological performance in mice