Le 2,2'-azino-bis (3-ethylbenztiazoline-6-acide sulfonique) (ABTS) peut etre oxyde de facon electrochimique en donnant un cation-radical colore et extremement stable. La presence de composes antioxydants retarde la formation de... more
Le 2,2'-azino-bis (3-ethylbenztiazoline-6-acide sulfonique) (ABTS) peut etre oxyde de facon electrochimique en donnant un cation-radical colore et extremement stable. La presence de composes antioxydants retarde la formation de l'ABTS et donc, l'apparition de la couleur sur une duree proportionnelle au pouvoir antioxydant de ces composes. Cette caracteristique a permis de mettre au point une methode electrochimique rapide et fiable permettant d'evaluer le pouvoir antioxydant, comme on a pu le verifier pour les composes phenoliques presents dans les raisins et les vins. (Bulletin O.I.V., 2000, vol. 73, n° 837-838, pp. 795-808).
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Research Interests: Organic Chemistry, Food Science, Medicine, Wine, Molecules, and 3 moreWinery, Wine Tasting, and organoleptic
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Research Interests: Chemistry, Analytical Chemistry, Chromatography, Comparative Study, Sample Preparation, and 14 moreWine, Solid Phase Extraction, Drying, Chemical Analysis, High Performance Liquid Chromatography, Analytical Method, Liquid Chromatography, Mycotoxin, Direct Injection, Direct Method, Standard Curve, Ochratoxin A, Standard Addition Method, and limit of detection
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There is considerable interest in the analysis of phenolic compounds due to their involvement in the organoleptic characteristics of foods and drinks, and their contribution to protection against cardiovascular diseases and cancers... more
There is considerable interest in the analysis of phenolic compounds due to their involvement in the organoleptic characteristics of foods and drinks, and their contribution to protection against cardiovascular diseases and cancers through their antioxidant activity. This article describes studies of the polyphenol content, both total (by means of the Folin- Ciocalteu method) and individual (by means of HPLC, LC-MS and LC-MS-MS) and the antioxidant power, of six varieties of grape over the course of their maturation. A good correlation is found to exist between the total polyphenol content of the samples and their antioxidant power, and both seem diminish along the maturation. 2003 Elsevier B.V. All rights reserved.
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Research Interests: Engineering, Chemistry, Chromatography, Electrochemistry, Polymers, and 15 moreFlavonoids, Medicine, Antioxidants, Polyphenols, Antioxidant, Agricultural, CHEMICAL SCIENCES, Phenols, Repeatability, Stilbenes, Reproducibility of Results, ABTS, Polyphenol, Sensitivity and Specificity, and Electrochemical method
In the present work, the polyphenolic profile of a complex matrix such as Amontillado sherry has been processed by means of high-speed counter-current chromatography (HSCCC) and characterized by HPLC-DAD-MS. An Amberlite XAD-7 column was... more
In the present work, the polyphenolic profile of a complex matrix such as Amontillado sherry has been processed by means of high-speed counter-current chromatography (HSCCC) and characterized by HPLC-DAD-MS. An Amberlite XAD-7 column was used to obtain the wine extract, and three different biphasic solvent systems were applied for HSCCC separation: MTBE (methyl tert-butyl ether)/n-butanol/acetonitrile/water (1.1/3/1.1/5+0.1% trifluoroacetic acid), MTBE/n-butanol/acetonitrile/water (2/2/1/5), and hexane/ethyl acetate/ethanol/water (1/5/1/5). As a result, 42 phenolic compounds and furanic derivatives have been identified by means of HPLC-DAD-MS, with 11 of them being identified for the first time in Sherry wines: 3-feruloylquinic acid, isovanillin, ethyl vanillate, furoic acid, dihydro-p-coumaric acid, 6-O-feruloylglucose, ethyl gallate, hydroxytyrosol, methyl protocatechuate, homoveratric acid and veratraldehyde. In addition, the antioxidant capacity (ABTS) of the obtained fractions ...
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The acceleration on the extraction by the sonication of phenolic compounds (measured as the Total Phenolic Index) from wood chips by wine distillates is studied in the present paper. Using the Arrhenius equation, the theoretical... more
The acceleration on the extraction by the sonication of phenolic compounds (measured as the Total Phenolic Index) from wood chips by wine distillates is studied in the present paper. Using the Arrhenius equation, the theoretical temperature at which the kinetics obtained by these sonicated extraction processes are equal to the kinetics of non-sonicated and thermally accelerated extractions, was calculated. By applying a pseudo-second order kinetic model, it was shown that the initial rate values obtained from the sonicated extractions were as high as those obtained from the thermal extractions carried out at a temperature at least 2.5 °C higher than the real temperature at which the experiment was performed. Higher power densities lead to higher initial rates of extraction, although very high power densities decrease the amount of phenols in equilibrium, probably due to the degradation processes. Additionally, the positive synergy between the sonication and the movement of the recir...
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Jerez (Sherry) is a well-known wine-producing region located in southern Spain, where world-renowned oenological products such as wines, vinegars, and brandies are produced. There are several factors that provide characteristic physical,... more
Jerez (Sherry) is a well-known wine-producing region located in southern Spain, where world-renowned oenological products such as wines, vinegars, and brandies are produced. There are several factors that provide characteristic physical, chemical, and sensory properties to the oenological products obtained in this Sherry region: the climate in the area with hot summers, mild winters, and with limited rainfall; the raw material used consisting on Palomino Fino, Moscatel, and Pedro Ximénez white grape varieties; the special vinification with fortified wines; and aging techniques such as a dynamic system of biological or oxidative aging. These special organoleptic characteristics are responsible for, among others, the aromatic profile of the wines, vinegars and brandies from the area, which explains why this is a subject that has been extensively researched over the years. This bibliographic review aims to compile the different scientific contributions that have been found to date, in ...
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The use of alternative types of wood has arisen for the aging of the Brandy de Jerez, on a pilot plant level. In particular, besides the use of American oak, two more types of oak have been studied, French oak and Spanish oak, allowed by... more
The use of alternative types of wood has arisen for the aging of the Brandy de Jerez, on a pilot plant level. In particular, besides the use of American oak, two more types of oak have been studied, French oak and Spanish oak, allowed by the Technical File for the ID Brandy de Jerez, and chestnut, which, though it is not officially allowed, is a type of wood which had been traditionally used in the area for the aging of wines and distillates. All of them have been studied with different toasting levels: Intense toasting and medium toasting. The study of the total phenolic composition (TPI), chromatic characteristics, organic acids, and sensory analysis have proven that chestnut leads to distillates with a higher amount of phenolic compounds and coloring intensity than oak. This behavior is the opposite as regards the toasting of the wood. Among the different types of oak, Spanish oak produces aged distillates with a higher phenolic composition and a higher color intensity. Regarding...
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BACKGROUNDThe present study investigated the volatile composition of a Pedro Ximénez sweet wine that had been aged in barrels made of different types of wood (Spanish oak, French oak, American oak and chestnut) and subjected to different... more
BACKGROUNDThe present study investigated the volatile composition of a Pedro Ximénez sweet wine that had been aged in barrels made of different types of wood (Spanish oak, French oak, American oak and chestnut) and subjected to different degrees of toasting (medium toasting and intense toasting). The analyses were carried out using stir bar sorptive extraction gas chromatography–mass spectrometry after validation of the matrix in this case.RESULTSGood values of linearity, precision, limits of detection and limits of quantification were obtained for the 36 compounds studied, six of which were identified for the first time in Pedro Ximénez (propyl acetate, cis‐3‐hexenyl acetate, benzyl acetate, guaiacol, trans‐whiskeylactone and 4‐ethylguaiacol). The volatile composition of the samples varied as the ageing process progressed, and higher volatile concentrations were obtained in samples aged in barrels that had been intensely toasted compared to in those with medium toasting. A multivar...