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1.
Aranzazu García M Victoria Ruiz-Méndez Concepción Romero Manuel Brenes 《Journal of the American Oil Chemists' Society》2006,83(2):159-164
By definition, virgin olive oil is consumed unrefined, although a great proportion of the olive oil produced has to be refined
to render it edible. Phenolic compounds are among the substances eliminated during the refining process; in the present work
these were characterized by HPLC, and their evolution during the different refining steps was studied. The complete refining
process removed most polyphenols from oils, but the behavior of individual compounds at each step also was observed. o-Diphenols
(hydroxytyrosol, catechol, and hydroxytyrosol acetate) and flavonoids (luteolin and apigenin) were eliminated first during
the alkaline treatment. Tyrosol and 4-ethylphenol remained in the oil until the deodorization step. A large amount of phenolic
compounds was discovered in the refining by-products such as soapstocks and deodorization distillates. In the latter streams,
the concentrations of tyrosol and 4-ethylphenol reached up to 149 and 3720 mg/kg by-product, respectively. This high level
of 4-ethylphenol and its well-known strong off-odor can interfere during further processing of the deodorization distillates,
and this must be taken into account when deciding what is to become of them. Similarly, the results of this work open the
possibility of recovering phenolic compounds from the “second centrifugation olive oils” by adding a new washing step prior
to the refining process. By including this new step, the most polar polyphenols, hydroxytyrosol and tyrosol, will diffuse
from oil to water and a concentration of up to 1400 mg/L of hydroxytyrosol may be achieved. 相似文献
2.
Manuel Brenes Francisco J. Hidalgo Aranzazu García José J. Rios Pedro García Rosario Zamora Antonio Garrido 《Journal of the American Oil Chemists' Society》2000,77(7):715-720
Polyphenols of olive oil show autoprotective, sensory, and nutritional-therapeutic effects. Two new phenolic compounds have
been isolated from virgin olive oils by preparative high-performance liquid chromatography and their structures established
on the basis of their mass spectra and nuclear magnetic resonance spectral data. The compounds identified are the lignans
pinoresinol and 1-acetoxypinoresinol. Both have been found in all the commercial virgin olive oils analyzed. Pinoresinol concentration
was rather similar in all the oils. In contrast, 1-acetoxypinoresinol concentration was higher in oils of the Arbequina and
Empeltre cultivars than in Picual or Picudo cultivars. Pinoresinol and 1-acetoxypinoresinol may represent the major phenolic
compounds in some Arbequina and Empeltre oils. Lignans possess biological and pharmacological properties and, therefore, the
two new compounds identified in olive oils may contribute to the reported beneficial effects which are attributed to polyphenols
on human health of a diet rich in olive oil. 相似文献
3.
Rocío Sánchez-Mangas Antonio García-Ferrrer Aranzazu de Juan Antonio Martín Arroyo 《Accident; analysis and prevention》2010,42(4):1048-1056
The number of deaths in road traffic accidents in Spain exceeds three thousand people each year. Public authorities have implemented some policies with the aim to reducing this number. Among them, the improvement of road quality standards and some legal changes encouraging careful driving behavior. However, less attention has been focused on one of the issues that may be critical to reducing the number of fatalities caused by traffic accidents: a quick emergency medical care. In this paper, we use a sample of more than 1400 accidents occurred on Spanish roads in May 2004. Our objective is to analyze to which extent a reduction of the time interval between the crash and the arrival of the emergency services to the crash scene is related to a lower probability of death. Our results suggest that a 10 min reduction of the medical response time can be statistically associated with an average decrease of the probability of death by one third, both on motorways and conventional roads. 相似文献
4.
Concepción Romero Aranzazu GarcíaEduardo Medina Mª Victoria Ruíz-MéndezAntonio de Castro Manuel Brenes 《Food chemistry》2010
An experimental investigation was carried out for the first time on the triterpenic acids in table olives. Maslinic acid was found in a higher concentration than oleanolic acid in the flesh of 17, unprocessed olive varieties, with the Picual and the Manzanilla varieties showing the highest and almost the lowest contents, respectively. The level of triterpenic acids in several types of commercial black and green olives ranged from 460 to 1470 mg/kg fruit, which represents a much higher value than reported for virgin olive oils. In fact, the NaOH treatment employed to debitter black and green olives reduced the concentrations of these substances in the flesh because of their solubilisation into alkaline solutions. Thus, natural black olives, which are not treated with NaOH, showed a higher concentration than 2000 mg/kg in the olive flesh. These results will contribute to the reevaluation of table olives from a nutritional and functional point of view because of the promising bioactivity properties attributed to olive triterpenic acids. 相似文献
5.
Jesus Garoz‐Ruiz Juan V. Perales‐Rondon Aranzazu Heras Alvaro Colina 《Israel journal of chemistry》2019,59(8):679-694
Spectroelectrochemistry (SEC) is a set of techniques with many advantages in the study and characterization of materials. Although SEC has not yet been widely used to study quantum dots (QDs), the information extracted from SEC experiments about these nanostructures is very useful. Most of the works that use SEC to study QDs are high‐quality pieces of research. This review intends to show how to perform SEC in an easy way and what information can be obtained using these techniques. Most of the examples shown in this review are related to semiconductor and carbon QDs. After a brief introduction, some optoelectronic properties of QDs and the main SEC techniques are described. The capabilities of SEC for the study of QDs are illustrated with examples extracted from literature. Finally, the needs of SEC to become a user‐friendly technique and its evolution to become more powerful are commented in the last section of the review. 相似文献
6.
L. Muñoz-Fernandez A. Sierra-Fernandez G. Flores-Carrasco O. Milošević M.E. Rabanal 《Advanced Powder Technology》2017,28(1):83-92
Micro/nanostructured systems based on metallic oxide (ZnO) with noble metal (Ag) on the surface (Ag/ZnO) are synthesized by solvothermal method from zinc nitrate hexahydrate (Zn(NO3)2·6H2O), zinc acetate dehydrate (Zn(CH3COO)2·2H2O), zinc acetylacetonate hydrate (Zn(C5H7O2)2·xH2O) and silver nitrate (Ag(NO3)) as precursors. In these systems, polyvinylpyrrolidone (PVP) is used as surfactant for controlling particle morphology, size and dispersion. The obtained materials are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), UV–vis diffuse reflectance spectroscopy (DRS), N2 gas adsorption–desorption (BET) and Raman spectroscopy (RS). By XRD results, all major peaks are indexed to the hexagonal wurtzite-type structure of the ZnO and samples with noble metal, extra diffraction peaks are detected which correspond to the face-centered-cubic (fcc) structure of the metallic Ag. Depending on used precursor, different morphologies have been obtained. Mainly, ZnO prims-like rods – NRs (with 0.8 ? aspect ratio ? 3.4) – have been observed. Quasi-spherical particles of metallic Ag (with diameters between 558 ± 111 μm and 22 ± 1 nm) have been detected on the ZnO surface. Photocatalytic results (all samples studied >30% MB degradation) verify the important effect of surfactant and the viability of synthesized Ag/ZnO micro/nanocomposites for environmental applications. 相似文献
7.
L.S. Gomez-Villalba A. Sierra-Fernandez O. Milosevic R. Fort M.E. Rabanal 《Advanced Powder Technology》2017,28(1):61-72
Micro and nanostructured brucite (Mg(OH2)) particles synthesized by hydrothermal method from solutions with high content of hydrazine (0.14 M) and nitrate (0.24 g) were compared with samples obtained from low hydrazine content (0.0002 M) and nitrate (0.12 g). The samples were heated at 180 °C for 4 h, 6 h and 12 h. XRD, TEM-HRTEM, SAED and image analysis techniques were used for the morphological and structural characterization. The effect of electron beam irradiation on the brucite dehydration was observed in atomic resolution images at 300 kV. Hexagonal crystals show differences in crystallinity, strains and kinetic of reaction. High hydrazine/nitrate samples have slightly larger crystals with better crystallinity, showing a strong preferential orientation. Rietveld refinements show how unit cell parameters are bigger in samples obtained with higher hydrazine/nitrate content, confirming also the preferential orientation along the 0 0 0 1 plane. Differences in the dehydration process show the rapid formation of a porous surface, the amorphised cortex or the presence of highly oriented strains in samples prepared from higher hydrazine/nitrate content. Conversely, crystals slightly smaller with randomly scattered defect surfaces showing the Mg(OH)2/MgO interphase in samples prepared with low hydrazine/nitrate content. Significant differences in the kinetic of reaction indicate how the dehydration process is faster in samples prepared with high hydrazine/nitrate content. 相似文献
8.
Izquierdo D Martinez A Heras A Lopez-Palacios J Ruiz V Dryfe RA Colina A 《Analytical chemistry》2012,84(13):5723-5730
Spatial scanning spectroelectrochemistry is a new analytical technique that provides spectral information at different distances from an electrified liquid/liquid interface where an electrochemical process takes place. As a proof of concept, we have studied two different electrochemical processes at the electrified liquid/liquid interface: (1) Ru(bpy)(3)(2+) transfer through the water/1,2-dichloroethane interface and (2) electrodeposition of Pd nanoparticles at the water/1,2-dichloroethane interface. The instrumental setup developed consists of a movable slit for the light beam to sample at well-defined positions on both sides of the interface, providing important information about the chemical process occurring. If the slit is scanned at different distances from the interface during an electrochemical experiment, a complete picture of the reactions and equilibria in the diffusion layer can be obtained. For example, in the case of the Ru(bpy)(3)(2+), the experiments show clearly how the complex is transferred from one phase to the other. In the case of electrosynthesis of Pd nanoparticles, it is demonstrated that nanoparticles are not only deposited at the interface but diffuse to the aqueous bulk solution. These in situ observations were confirmed by ex situ experiments using transmission electron microscopy. 相似文献
9.
Aranzazu García Manuel Brenes Mª Carmen Dobarganes Concepción Romero Ma Victoria Ruiz‐Méndez 《European Journal of Lipid Science and Technology》2008,110(12):1136-1141
Triterpenic acids are natural compounds present in plants and foods with beneficial properties for human health and thus they are desirable in the food, cosmetics and pharmaceutical industries. Pomace olive is considered a good source of these substances. In this study, oleanolic and maslinic acids were found to be the main triterpenic acids identified in pomace olive oil obtained from stored “Alpeorujo”. Determination of the two acids was achieved by a new procedure that consists of extracting the acids from the oil with a mixture of methanol/ethanol, and then separating and quantifying them by HPLC. Results showed that their concentration increased up to 16 g/kg of oil during storage of the pomace in large ponds for 7 months. The concentration of both triterpenic acids was similar in the pomace olive oil obtained by using the centrifugation system. By contrast, a much lower concentration of maslinic than oleanolic acid was detected in pomace olive oils obtained by solvent extraction from the previously centrifugated “Alpeorujo” paste. These triterpenic acids also contributed to the acidity of the crude oil. Likewise, the oil of the pomace paste was enriched in other substances such as 4‐ethylphenol and aliphatic alcohols during the storage of the paste in large ponds. Consequently, crude pomace olive oil can be considered a good source of triterpenic acids when obtained from a stored olive paste. 相似文献
10.
Bollen MA Garcia A Cordewener JH Wichers HJ Helsper JP Savelkoul HF van Boekel MA 《Molecular nutrition & food research》2007,51(12):1527-1536
Birch pollen allergy is predominantly caused by the major allergen Bet v 1 and can lead to crossreactions with homologous proteins in food. Two major cross-reactive food allergens are Dau c 1 from carrot and Api g 1 from celery, which have never been purified from their natural source. Here, we describe a non-denaturing purification method for obtaining natural Bet v 1, Dau c 1 and Api g 1, comprising of ammonium sulfate precipitation, hydrophobic interaction chromatography and size exclusion chromatography. This method resulted in 98-99% pure isoform mixtures for each allergen. Characterization of these isoform mixtures with Q-TOF MS/MS clearly showed earlier reported isoforms of Bet v 1, Dau c 1 and Api g 1, but also new isoforms. The presence of secondary structure in the three purified allergens was demonstrated via circular dichroism and showed high similarity. The immune reactivity of the natural allergens was compared with recombinant proteins by Western blot and ELISA and showed similar reactivity. 相似文献