196 resultados para Starch hydrolysis
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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The present research was undertaken to explore the influence of fructooligosaccharides (FOS) on the functional and thermal properties of sour cassava starch and the quality characteristics of gluten-free (GF) cheese bread. Fructooligosaccharides were used to replace sour cassava starch at substitution level of 9% (SF1), 17% (SF2), and 29% (SF3). The functional and thermal properties of the starch-FOS mixtures were determined by the water absorption index (WAI), water solubility index (WSI), pasting profile analysis, thermal transition temperatures and enthalpy of gelatinization. Moreover, the GF cheese breads with starch-FOS mixtures were analyzed for height, diameter, weight, specific volume and dough moisture content. The sample with the highest FOS content (SF3) presented the lowest WAI (1.44), peak (62.4 rapid visco units (RVU), breakdown (53.4 RVU), final (13.8 RVU), and setback (4.9 RVU) viscosities, dough moisture content (31.7%), and enthalpy of gelatinization (9.5 J/g) and the highest WSI (29.4%) and pasting temperature (69.1 degrees C). The height, diameter and specific volume of GF cheese bread samples made from sour cassava starch were 3.14 cm, 6.35 cm, and 1.49 cm(3)/g, respectively. The SF1 mixture samples resulted in a 3.01 cm height, 6.34 cm diameter, and 1.55 cm(3)/g specific volume. According to Brazilian food labeling regulations, the latter product cannot be categorized as a good source of fiber because the minimum level of fiber per portion was not reached.
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The development of polymeric blends to be used as matrices for bone regeneration is a hot topic nowadays. In this article we report on the blends composed by corn starch and poly(vinylidene fluoride), PVDF, or poly(vinylidene fluoride-trifluoroethylene), P(VDF-TrFE), to obtain biocompatible materials. Blends were produced by compressing/annealing and chemically/structurally characterized by micro-Raman scattering and Fourier transform infrared (FTIR) absorption spectroscopies, dynamic mechanical analysis (DMA) and scanning electron microscopy (SEM), besides in vivo study to evaluate the tissue response. Vibrational spectroscopy reveals no chemical interaction between the polymers and starch, absence of material degradation due to compressing/annealing process or organism implantation, and maintenance of a and ferroelectric crystalline phases of PVDF and P(VDF-TrFE), respectively. As a consequence of absence of interaction between polymers and starch, it was possible to identify by SEM each material, with starch acting as filler. Elastic modulus (E') obtained from DMA measurement, independent of the material proportion used in blends, reaches values close to those of cancellous bone. Finally, the in vivo study in animals shows that the blends, regardless of the composition, were tolerated by cancellous bone. (C) 2013 Elsevier B.V. All rights reserved.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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The properties of a previously unknown enzyme, denominated cyclodextrin glycosyltransferase, produced from Bacillus lehensis, were evaluated using affinity chromatography for protein purification. Enzyme characteristics (optimum pH and temperature; pH and temperature stability), the influence of substances on the enzyme activity, enzyme kinetics, and cyclodextrin production were analysed. Cyclodextrin glycosyltransferase was purified up to 320.74-fold by affinity chromatography using beta-cyclodextrin as the binder and it exhibited 8.71% activity recovery. This enzyme is a monomer with a molecular weight of 81.27 kDa, as estimated by SDS-PAGE. Optimum temperature and pH for cydodextrin glycosyltransferase were 55 degrees C and 8.0, respectively. The Michaelis-Menten constant was 8.62 g/l during maximum velocity of 0.858 g/l.h.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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The biodegradability properties of poly(epsilon-caprolactone) (PCL) and modified adipate-starch (AS) blends, using Edenol-3203 (E) as a starch plasticizer, were investigated in laboratory by burial tests of the samples in previously analyzed agricultural soil. The biodegradation process was carried out using the respirometric test according to ASTM D 5988-96, and the mineralization was followed by both variables such as carbon dioxide evolution and mass loss. The results indicated that the presence of AS-E accelerated the biodegradation rate as expected.
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Mixed calcium and copper oxalates, with different proportions of Ca2+ and Cu2+ ions, were precipitated by dimethyl oxalate hydrolysis in homogeneous solution. The compounds were evaluated by means of scanning electron microscopy, energy dispersive X-ray spectroscopy, thermogravimetry (TG), and differential thermal analysis (DTA). The results suggested quantitative precipitation without solid solution formation. From the TG and DTA curves, it was possible to evaluate the Ca2+ ion proportion in the solid phase and to confirm the precipitation of the individual species.
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Starch isolated from non-edible Aesculus hippocastanum seeds was characterized and used for preparing starch-based materials. The apparent amylose content of the isolated starch was 33.1%. The size of starch granules ranged from 0.7 to 35 pm, and correlated with the shape of granules (spherical, oval and irregular). The chain length distribution profile of amylopectin showed two peaks, at polymerization degree (DP) of 12 and 41-43. Around 53% of branch unit chains had DP in the range of 11-20. A. hippocastanum starch displayed a typical C-type pattern and the maximum decomposition temperature was 317 degrees C.Thermoplastic starch (TPS) prepared from A. hippocastanum with glycerol and processed by melt blending exhibited adequate mechanical and thermal properties. In contrast, plasticized TPS with glycerol:malic acid (1:1) showed lower thermal stability and a pasty and sticky behavior, indicating that malic acid accelerates degradation of starch during processing. (C) 2014 Elsevier Ltd. All rights reserved.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Recently there is a great quest of producing alcohol from starchy resources, replacing the sugar cane. The most common starchy sources are cassava, maize and sweet potatoes and a lot of research are been realized with excellent results. In this work it was evaluated the influence of the concentration of dry matter on the enzymatic hydrolysis process of starch from sweet potato for ethanol production. Through the sweet potato was produced a flour using a low-cost method and easy operation equipments. The sweet potato flour was characterized physical and chemically and from these results was prepared the treatments for enzymatic hydrolysis. The experimental design considered as independent variable the dry matter concentration of the sweet potato flour in 3 levels; 10, 15 and 20% in the formulation of suspensions. The other variables were keeping constant being: temperature in the 1° hydrolysis step of 90°C and time of 2 hours; temperature in the 2° saccharification step of 60°C and time of 17 hours. The hydrolysates obtained at the three assays were transferred to six liter enlerynmeyer and inoculated with a biologic catalyst, Saccharomyces, dehydrated yeasts of Saccharomyces cerevisiae CAT 1, at a rate of 5% in weight. The flasks were placed in a shaker type orbital with controlled temperature of 30°C during a time of 15 hours. The initial reducer sugars concentration and respective ethanol concentrations in wine were: 11.2% glucose and 2.16% ethanol in the suspension with 10% of dry matter; 13.5% glucose and 4.39% ethanol with 15% and 17.5% glucose and 6.03% ethanol in suspension with 20% of dry matter. ix The results showed that the higher percentage of dry matter carried out to higher sugar yield in hydrolyzed. It was possible observed that products quality improved with a higher concentration of dry matter