A leitura como um processo cognitivo
Figueiredo, Olívia Maria
1999-01-01
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Pomegranate peels are very rich in bioactive compounds,
particularly antioxidants, that when properly extracted,
may be used for different applications such as food, cosmetics,
and pharmaceutics. In this paper, we studied the effect
of high-pressure extraction on antioxidant activity and bioactive
compounds (total phenolics, tannins, flavonoids, and anthocyanins)
of pomegranate peel, using a Box–Behnken design
to evaluate the effects of pressure, extraction time, and
ethanol concentration to estimate the optimum extraction conditions
by response surface methodology (RSM). Individual
phenolics, tannins, and anthocyanins were also identified and
quantified using the optimum extraction conditions identified
by RSM. The results indicated that a quadratic polynomial
model could be used to optimize high-pressure extraction of
b...
The constant growing demand for vegetable oil for biodiesel and food is raising many environmental concerns about the sustainability of its production based on crops. Oleaginous yeasts show great potential to end with those concerns due to their high lipid productivity in small areas. To evaluate their productivity in lipids, an efficient and reproducible extraction process should be used. As no standard extraction process is available for the extraction of yeast lipids, an optimized extraction process is presented. In this work, the lipids extraction process for the yeasts Rhodotorula glutinis and Lipomyces kononenkoae is optimized using bead beating for cell rupture and introducing adaptations of the two most used extraction methods (Bligh and Dyer and Folch). For Rhodotorula g. the optimum extraction conditions are obtained by the B...
The field of metabolomics is getting more and more popular and a wide range of different sample preparation procedures are in use by different laboratories. Chemical extraction methods using one or more organic solvents as the extraction agent are the most commonly used approach to extract intracellular metabolites and generate metabolite profiles. Metabolite profiles are the scaffold supporting the biological interpretation in metabolomics. Therefore, we aimed to address the following fundamental question: can we obtain similar metabolomic results and, consequently, reach the same biological interpretation by using different protocols for extraction of intracellular metabolites? We have used four different methods for extraction of intracellular metabolites using four different microbial cell types (Gram negative bacterium, Gram posit...
In this study, a hydrometallurgical treatment involving the solvent extraction and recovery of some heavy metals from a sulphuric acid leach
solution of galvanic sludge, using di-(2-ethylhexyl)-phosphoric acid (D2EHPA) and bis-(2,4,4- trimethylpentyl)-phosphinic acid (Cyanex
272), both diluted in kerosene, has been investigated.
The preliminary tests revealed the necessity to remove other metal species than zinc and nickel, contained in the leach solution, and therefore, processes to cement copper and precipitate chromium were then applied to finally obtain a Zn and Ni pregnant solution prior to solvent extraction. For the experimental conditions studied, Cyanex 272 showed a good recovery of Zn after the stripping stage using H2SO4, but D2EHPA effectively promoted a higher Zn extraction than Cyanex 272 did. The dependence of the sol...
Fish skins constitute an important fraction of the enormous amount of wastes produced by the fish processing industry, part of which may be valorized through the extraction of gelatins. This research exploited the extraction and characterization of gelatins from the skin of three seawater fish species, namely yellowfin tuna (Thunnus albacares), blue shark (Prionace glauca), and greenland halibut (Reinhardtius hippoglossoides). Characterization included chemical composition, rheology, structure, texture, and molecular weight, whereas extraction studies intended to reduce costly steps during extraction process (reagents concentration, water consumption, and time of processing), while maintaining extraction efficiency. Chemical and physical characterization of the obtained gelatins revealed that the species from which the gelatin was extr...
Lipidome profile of fluids and tissues is a growing field as the role of lipids as signaling molecules is increasingly understood, relying on an effective and representative extraction of the lipids present. A number of solvent systems suitable for lipid extraction are commonly in use, though no comprehensive investigation of their effectiveness across multiple lipid classes has been carried out. To address this, human LDL from normolipidemic volunteers was used to evaluate five different solvent extraction protocols [Folch, Bligh and Dyer, acidified Bligh and Dyer, methanol (MeOH)-tert-butyl methyl ether (TBME), and hexane-isopropanol] and the extracted lipids were analyzed by LC-MS in a high-resolution instrument equipped with polarity switching. Overall, more than 350 different lipid species from 19 lipid subclasses were identified....
Response surface methodology (RSM) was employed for the first time to optimize high pressure extraction (HPE) conditions of bioactive compounds from pansies, namely: pressure (X1: 0–500 MPa), time (X2: 5–15 min) and ethanol concentration (X3: 0–100%). Consistent fittings using second-order polynomial models
were obtained for flavonoids, tannins, anthocyanins, total reducing capacity (TRC) and DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging activity. The optimum extraction conditions based on combination responses for TRC, tannins and anthocyanins were: X1 = 384 MPa, X2 = 15 min and X3 = 35% (v/v) ethanol, shortening the extraction time when compared to the classic method of stirring (approx. 24 h). When the optimum extraction conditions were applied, 65.1 mg of TRC, 42.8 mg of tannins and 56.15 mg of anthocyanins/g dried flowe...
about the influence of the extraction process on composition of the extracts and in ulvan itself. In this
context, the two main objectives of the present work are (1) the establishment of an efficient extraction
process for ulvan and (2) development of an accurate characterization methodology to evaluate the
extract composition and ulvan content.
Three ulvan-rich extracts obtained by different schemes of extraction were studied. The methodology
for the analysis was improved and a detailed analysis of extracted ulvan was provided. The polysaccharide
is rich in ulvanobiuronic acid 3-sulfate type A [→4)- -d-GlcAp-(1
→
4)- -l-Rhap 3S-(1→], with minor
amounts of ulvanobiuronic acid 3-sulfate type B [→4)- -l-IdoAp-(1
→
4)- -l-Rhap 3S-(1→]. The extract
with the higher degree of purification is a high molecular weight polysaccharid...
This study compares three extraction techniques (maceration, microwave and ultrasound) for catechin recover from Arbutus unedo fruit extracts. To obtain the conditions that maximize catechin extraction yield, a response surface methodology was applied using a 3-level full factorial Box–Behnken design in which the processing time (t), temperature (T), ultrasonic power (W) and ethanol percentage (Et%) were the relevant independent variables with the response (catechin content, mg/g dw) measured by HPLC-PDA. A fixed solid/solvent ratio of 50 g/L was used in all techniques. Maceration and microwave extractions were found to be the most effective methods, capable of yielding 1.38 ± 0.1 and 1.70 ± 0.3 mg/g dw of catechin, respectively at the optimal extraction conditions. The optimal conditions for maceration were 93.2 ± 3.7 min, 79.6 ± 5.2 ...
Extraction of fibrinolytic protease from Streptomyces sp. DPUA1576 fermentation broth was performed using polyethylene glycol (PEG) – phosphate salts aqueous two phase system (ATPS). The influence of pH, PEG molar mass, PEG and phosphate concentrations on fibrinolytic protease partition coefficient (K) were evaluated by 24 full factorial design. Fibrinolytic protease partitioned preferentially to the (PEG)-rich phase with the highest partition coefficient (K = 37.00) obtained in the system 20% (w/w) PEG 1500 (g/mol)-14% (w/w) phosphate at pH 8.0. The system that allowed for the highest extraction consisted of 15% (w/w) PEG 3350-12% (w/w) phosphate, at pH 7.0. In these conditions, a purification factor of 1.51 was obtained for a partition coefficient of 6.41 with the fibrinolytic activity (FA) retained in the top phase. Obtained results...
