973 resultados para classification of the sour cassava starch
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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In this work, cassava starch was modified by treatment with sodium hypochlorite (NaClO) at different concentrations (0.8, 2.0 and 5.0 % of active chlorine) and selected physicochemical properties of the oxidized starches were investigated. The native and modified samples were evaluated considering moisture, carboxyl content, apparent viscosity, susceptibility to syneresis, mid-infrared spectroscopy and crystallinity index. The treatment with NaClO resulted in alterations in carboxyl content of the oxidized starches that increased with increasing concentration of the oxidant. Oxidized starches also showed higher susceptibility to syneresis, as assessed by the release of liquid during freezing and thawing. Apparent viscosity analysis showed decrease in peak viscosity of the oxidized starches. X-ray diffractograms showed that the oxidation influenced the extent of cassava starch relative crystallinity found to lie between 34.4 % (native) and 39.9 % (2.0 % active chlorine). The infrared spectra are sensitive to structural changes on starch macromolecules and presented characteristic peaks as C-O-C of the six carbon glucose ring absorbs at 1,150-1,085 cm -1 and due to axial deformation these bands changed with the crystal structure of the starch samples. © 2012 Association of Food Scientists & Technologists (India).
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The use of chemically modified starches is widely accepted in various industries, with several applications. In this research, natural cassava starch granules were treated with standard sodium hypochlorite solution at 0.8, 2.0, and 5.0 g Cl/100 g starch. The native and modified starch samples were investigated by means of the following techniques: simultaneous thermogravimetry-differential thermal analysis, which allowed us to verify the thermal decomposition associated with endothermic or exothermic phenomena; and differential scanning calorimetry that was used to determine gelatinization enthalpy as well as the rapid viscoamylographic analysis that provided the pasting temperature and viscosity. By means of non-contact-atomic force microscopy method and X-ray powder patterns diffractometry, it was possible to observe the surface morphology, topography of starch granules, and alterations in the granules' crystallinity. © 2012 Akadémiai Kiadó, Budapest, Hungary.
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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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Starch is one of the most important sources of reserve of carbohydrate in plants and the main source in the human diet due to its abundance in the nature. There no other food ingredient that can be compared with starch in terms of sheer versatility of application in the food industry. Unprocessed native starches are structurally too weak and functionally too restricted for application in today’s advanced food and industrial technologies. The main objective of this study was to compare the thermal behavior of native cassava starch and those treated with hydrogen peroxide, as well as those treated with hydrogen peroxide and ferrous sulfate. The cassava starch was extracted from cassava roots (Manihot esculenta, Crantz) and treated by standardized hydrogen peroxide (H2 O2 ) solutions at 1, 2 and 3% (with or without FeSO4 ). Investigated by using they are thermoanalytical techniques: thermogravimetry - TG, differential thermal analysis – DTA and differential scanning calorimetry - DSC, as well as optical microscopy and X-ray powder diffractometry. The results showed the steps of thermal decomposition, changes in temperatures and in gelatinization enthalpy and small changes in crystallinity of the granules.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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In this this study, glycerol content and its incorporation method on tensile and barrier properties of biodegradable films (BF) based on cassava starch were analyzed. ANOVA showed that the glycerol incorporation method did not influence the results (P > 0.05), however the glycerol content influenced significantly the tensile and barrier properties of the films (P < 0.05). Films prepared with lower glycerol content presented better tensile and barrier properties than films with higher content. Films were then prepared with addition of clay nanoparticles and their tensile and barrier properties and glass transition temperature were measured. ANOVA indicated that both glycerol and clay nanoparticles influenced significantly the tensile and barrier properties (P < 0.05), diminishing film permeability when clay nanoparticles were present, while the glass transition temperature was not influenced (P > 0.05). (C) 2011 Elsevier Ltd. All rights reserved.
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In this work, it was evaluated the effect of moisture content on the structural and dielectric properties of cassava starch films by means of Fourier Transform infrared spectroscopy (FTIR), impedancimetric, and gravimetric analysis. The film samples were equilibrated in hermetically sealed desiccators, containing different saturated salts in water in order to promote activity of water between 0.11 and 0.85. The position and amplitude of the peaks in the fingerprint region of the FTIR spectra were changed due to the modifications in the interactions between the polymeric chains and water molecules. These effects may be related to the formation of semi-crystalline regions in the film structure. The dielectric properties of the films were also strongly dependent on the moisture content, showing a non-linear and a linear region, which was attributed to the domain of bound and free water in the film, respectively. The gravimetric analyzes showed the typical sigmoidal behavior, attributed to the way the water interacts with the biopolymer. Finally, the flexibility of the films increased with water content increasing.
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Mode of access: Internet.
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Starches are applied in several fields of industry. Amylose and amylopectin (natural polymers) constitute the starch in vegetable cells. In some processes native starches cannot support high stress conditions (high temperatures/acidity). Then, modification methods are developed aiming the improving of starch technological utilization. Oxidative modification with H2O2 has been the subject of many researches. UV rays as well microwave irradiation can be used. The aim was to confirm possible thermogravimetric alterations in native cassava starch (A) granules due to a double starch modification: 1st step) H2O2 standard solutions 0.1 mol L-1 (B), 0.2 mol L-1 (C) and 0.3 mol L-1 (D) and UV rays exposure for 1h; 2nd step) microwave irradiation for 5 min. The results of thermogravimetric curves (TG-DTA) show that the behaviors of the starch proprieties were modified. Highlighting, the modified samples C and D showed a decrease on the thermal stability step. This alteration turned them suitable to many field of industry like the paper one.
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The Subaxial Injury Classification (SLIC) system and severity score has been developed to help surgeons in the decision-making process of treatment of subaxial cervical spine injuries. A detailed description of all potential scored injures of the SLIC is lacking. We performed a systematic review in the PubMed database from 2007 to 2014 to describe the relationship between the scored injuries in the SLIC and their eventual treatment according to the system score. Patients with an SLIC of 1-3 points (conservative treatment) are neurologically intact with the spinous process, laminar or small facet fractures. Patients with compression and burst fractures who are neurologically intact are also treated nonsurgically. Patients with an SLIC of 4 points may have an incomplete spinal cord injury such as a central cord syndrome, compression injuries with incomplete neurologic deficits and burst fractures with complete neurologic deficits. SLIC of 5-10 points includes distraction and rotational injuries, traumatic disc herniation in the setting of a neurological deficit and burst fractures with an incomplete neurologic deficit. The SLIC injury severity score can help surgeons guide fracture treatment. Knowledge of the potential scored injures and their relationships with the SLIC are of paramount importance for spine surgeons who treated subaxial cervical spine injuries.
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To compare the distributions of patients with clinical-pathological subtypes of luminal B-like breast cancer according to the 2011 and 2013 St. Gallen International Breast Cancer Conference Expert Panel. We studied 142 women with breast cancer who were positive to estrogen receptor and had been treated in São Paulo state, southeast Brazil. The expression of the following receptors was assessed by immunohistochemistry: estrogen, progesterone (PR) and Ki-67. The expression of HER-2 was measured by fluorescent in situ hybridization analysis in tissue microarray. There were 29 cases of luminal A breast cancers according to the 2011 St. Gallen International Breast Cancer Conference Expert Panel that were classified as luminal B-like in the 2013 version. Among the 65 luminal B-like breast cancer cases, 29 (45%) were previous luminal A tumors, 15 cases (20%) had a Ki-67 >14% and were at least 20% PR positive and 21 cases (35%) had Ki-67 >14% and more than 20% were PR positive. The 2013 St. Gallen consensus updated the definition of intrinsic molecular subtypes and increased the number of patients classified as having luminal B-like breast cancer in our series, for whom the use of cytotoxic drugs will probably be proposed with additional treatment cost.
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Echinolaena inflexa (Poir.) Chase is an abundant C3 grass species with high biomass production in the Brazilian savanna (cerrado); Melinis minutiflora Beauv. is an African C4 forage grass widespread in cerrado and probably displacing some native herbaceous species. In the present work, we analysed seasonally the content and composition of soluble carbohydrates, the starch amounts and the above-ground biomass (phytomass) of E. inflexa and M. minutiflora plants harvested in two transects at 5 and 130 m from the border in a restrict area of cerrado at the Biological Reserve and Experimental Station of Mogi-Guaçu (SP, Brazil). Results showed that water soluble carbohydrates and starch amounts from the shoots of both species varied according to the time of the year, whilst in the underground organs, variations were observed mainly in relation to the transects. Marked differences in the pattern of the above-ground biomass production between these two grasses relative to their location in the Reserve were also observed, with two peaks of the invasive species (July and January) at the Reserve border. The differences in carbohydrate accumulation, partitioning and composition of individual sugars concerning time of the year and location in the Reserve were more related to the annual growth cycle of both grasses and possibly to specific physiological responses of M. minutiflora to disturbed environments in the Reserve border.
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This paper describes a new food classification which assigns foodstuffs according to the extent and purpose of the industrial processing applied to them. Three main groups are defined: unprocessed or minimally processed foods (group 1), processed culinary and food industry ingredients (group 2), and ultra-processed food products (group 3). The use of this classification is illustrated by applying it to data collected in the Brazilian Household Budget Survey which was conducted in 2002/2003 through a probabilistic sample of 48,470 Brazilian households. The average daily food availability was 1,792 kcal/person being 42.5% from group 1 (mostly rice and beans and meat and milk), 37.5% from group 2 (mostly vegetable oils, sugar, and flours), and 20% from group 3 (mostly breads, biscuits, sweets, soft drinks, and sausages). The share of group 3 foods increased with income, and represented almost one third of all calories in higher income households. The impact of the replacement of group 1 foods and group 2 ingredients by group 3 products on the overall quality of the diet, eating patterns and health is discussed.
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Aims. In this work, we describe the pipeline for the fast supervised classification of light curves observed by the CoRoT exoplanet CCDs. We present the classification results obtained for the first four measured fields, which represent a one-year in-orbit operation. Methods. The basis of the adopted supervised classification methodology has been described in detail in a previous paper, as is its application to the OGLE database. Here, we present the modifications of the algorithms and of the training set to optimize the performance when applied to the CoRoT data. Results. Classification results are presented for the observed fields IRa01, SRc01, LRc01, and LRa01 of the CoRoT mission. Statistics on the number of variables and the number of objects per class are given and typical light curves of high-probability candidates are shown. We also report on new stellar variability types discovered in the CoRoT data. The full classification results are publicly available.