A leitura como um processo cognitivo
Figueiredo, Olívia Maria
1999-01-01
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You search for extraction and 8,991 records were found.
Sensorial analysis and electronic aroma detection
to compare olive oils produced by different extraction
methods.
A sensorial analysis and an aroma analysis by electronic
sensory devices were used to compare olive oils produced
according to two different extraction methods.
The extraction methods compared were the press
system and two phase decanter. Samples were taken from
the harvests of 2002-2004 and the olives were all from
the same variety. The variety used was the Portuguese
Galega sp. Olives were picked and technologically handled
under predetermined and supervised conditions. Olive oils
produced were better classified when the sensory analysis
by a panel was applied than when an electronic sensory
analysis was performed, even after sensor optimization. This
observation is in accordance with the fact that olive oil has a
low vol...
Protein extraction and the proteome of Lactobacillus delbrueckii subsp. bulgaricus were studied
using different stains. The reversible silver staining technique was shown to be more sensitive than the
irreversible silver stain. Coomassie colloidal was demonstrated to be as sensitive as reversible silver stain;
however, the Coomassie colloidal blue solution developed a higher background and for sample preparation
was more time-consuming.
The influence of ohmic heating (OH) through the application of moderate electric fields on phytochemical compounds recovery from colored potato (Solanum tuberosum L. var. Vitelotte) was studied. A BoxBehnken design was used to simultaneously assess the effects of operational parameters such as electric field strength, temperature and process time on the yields of anthocyanins and total phenolic recovery on pretreatment of potato samples. From the analysis of the model, electric field, temperature and time were shown to have independent and interactive effects on the values of extraction yields. Aqueous extraction of phytochemical compounds after pretreatments can be described by using a two-step model involving simultaneous washing and diffusion of the solutes from the samples. Results shows that electrical fields of low energy levels ...
This protocol describes the separation of marine meiofauna from sediment and subsequent
environmental DNA extraction. In this study meiofauna samples were taken with a 45 mm core from
the upper 5 to 10 cm of sediment layer. Separation from sediment was achieved using a decantation
process followed by isolation from fine silt using repetitive centrifugation steps with a 1.16 specific
gravity (sg) LUDOX-TM solution. Meiofauna were deliberately separated from macrofauna by using
a 1 mm sieve on top of a bottle-top sterile 45 !M sieve. High quality DNA was subsequently
obtained using the QIAamp DNA Blood Maxi Kit (Qiagen) with minor adjustments to the
manufacturer’s protocol. This procedure allowed efficient isolation of meiofaunal representatives
from marine sediments and also extraction of high quality environmental DNA that can ...
An overview of the studies carried out in our laboratories on supercritical fluid extraction (SFE) of volatile oils from seven aromatic plants: pennyroyal (Mentha pulegium L.), fennel seeds (Foeniculum vulgare Mill.), coriander (Coriandrum sativum L.), savory (Satureja fruticosa Beguinot), winter savory (Satureja montana L.), cotton lavender (Santolina chamaecyparisus) and thyme (Thymus vulgaris), is presented. A flow apparatus with a 1 L extractor and two 0.27 L separators was built to perform studies at temperatures ranging from 298 to 353 K and pressures up to 30.0 MPa. The best compromise between yield and composition compared with hydrodistillation (HD) was achieved selecting the optimum experimental conditions of extraction and fractionation. The major differences between HD and SFE oils is the presence of a small percentage of c...
Solvent extraction is considered as a multi-criteria optimization problem, since several chemical species with
similar extraction kinetic properties are frequently present in the aqueous phase and the selective extraction
is not practicable. This optimization, applied to mixer–settler units, considers the best parameters and
operating conditions, as well as the best structure or process flow-sheet. Global process optimization is
performed for a specific flow-sheet and a comparison of Pareto curves for different flow-sheets is made. The
positive weight sum approach linked to the sequential quadratic programming method is used to obtain the
Pareto set.
In all investigated structures, recovery increases with hold-up, residence time and agitation speed, while the
purity has an opposite behaviour. For the same treatment capacity, co...
A supercritical fluid extraction (SFE) with pure CO2 and ethanol as a co-solvent (10 %) of spent coffee grounds was carried out at temperatures from 313 K to 333 K, pressures up to 40.0 MPa and the results obtained were compared with those of the conventional Soxhlet method using n-hexane as a solvent. The best extraction yield (12.0 %) was achieved by SFE with CO2+10 % ethanol, compared to 9.5 - 10.7 % by SFE with pure CO2 and 10.4 % with n-hexane. The antioxidant potential was evaluated by DPPH method and the best antioxidant activity was exhibited by the spent coffee oil obtained by SFE, CO2+10 % ethanol. The quantification and the identification of the oils composition were carried out by NMR. The main constituents of the extracted oils referred to the triacylglycerols (TAGs, 98.9 - 96.8 %). Minor amounts of 1,2 diacylglycerols (1,...
A methodology for the determination of the pesticide chlorfenvinphos by
microwave-assisted solvent extraction and square-wave cathodic stripping voltammetry
at a mercury film ultramicroelectrode in soil samples is proposed. Optimization of
microwave solvent extraction performed with two soils, selected for having significantly
different properties, indicated that the optimum solvent for extracting chlorfenvinphos is
hexane-acetone (1:1, v/v). The voltammetric procedure is based on controlled adsorptive
accumulation of the insecticide at the potential of -0.60 V (vs. Ag/AgCl) in the presence
of Britton-Robinson buffer (pH 6.2). The detection limit obtained for a 10 s collection
time was 3.0 x 10-8 mol l-1. The validity of the developed methodology was
assessed by recovery experiments at the 0.100 µg g-1 level. The average recov...
This paper presents a comprehensive approach to effectively extract cartographic urban data from high resolution satellite imagery. It
consists of a sequence of image processing techniques, for image segmentation, based on RGB band separation, analysis and preprocessing,
followed by a morphological-based approach for data segmentation. The chosen image objects for this study are roof-tile
buildings and road network. The first step of this approach consists of a spectral response evaluation for roof-tile building objects in
a dense urban environment, being those enhanced through proper sequence of standard arithmetic operators, applied to RGB bands,
segmented and generalized. The second step aims at urban road network segmentation for cartographic representation purposes, by
combining watershed and dual reconstruction morphological tran...
The harvest period is one of the most important
factors influencing olive oil quality. This period is extended
for several months and the late-extracted olive oils are
characterized by quality loss and reduced resistance to
oxidation. The aim of this work was to verify the effect of
olive leaves addition during the oil extraction process in the
olive oils quality and composition. In two consecutive years
(2009 and 2010), different olive leaves amounts (1%, 2.5%,
5% and 10% w/w) were added during the extraction process
of cv. Cobrançosa olive fruits, collected in the late season.
Standard quality parameters, oxidative stability, fatty acids
profile, tocopherols, chlorophylls, and carotenoids contents
were evaluated. Olive leaves addition induces a slight
increase in acidity, peroxide value, K232, and K270 without
compromis...
