Biomedical subjects

Carmelo García Barroso

Publications and source records attributed to Carmelo García Barroso.

8 recordsLinked to original sources

PubMed2005

Optimisation of stir bar sorptive extraction applied to the determination of volatile compounds in vinegars.

Stir bar sorptive extraction (SBSE) was evaluated for analysing volatile compounds in vinegar. The extraction and desorption analytical conditions have been optimised using a two-level factorial design expanded further to a central composite design. This chemometric tool is very appropriate in screening experiments where the aim is to investigate several possibly influential and/or interacting factors. For the extraction step, the optimum analytical conditions were: sample volume 25 ml without dilution, sampling time 120 min, NaCl content 5.85 g, and stirring speed 1250 rpm. For the desorption step, the optimised analytical conditions were: desorption temperature 300 degrees C, cryofocusing temperature -140 degrees C, flow of helium 75 ml min(-1), and desorption time 10 min. The SBSE procedure developed shows detection limits, and linear ranges adequate for analysing this type of compounds. The repeatability values obtained were lower than 10%. SBSE is a very simple, solvent-free, fast technique with better sensitivities, in general, than SPME. However, a disadvantage of this technique is that, up to now, the stir bar offers a limited enrichment capability for polar compounds because is only available with PDMS coating.

Acetic Acid↗

PubMed2005

Sugar contents of Brandy de Jerez during its aging.

Brandy de Jerez is aged in American oak casks according to the traditional dynamic system (Soleras y Criaderas) and sometimes additionally by the static system (Anadas). The experimental arrangement used here for the analytical monitoring of brandy aging consisted of 15 casks, 12 of which were set up for aging by the dynamic system, which is well established in the denomination of origin area, whereas the other 3 contained the same brandy but aged according to the static system. This paper studies the kinetics of sugar extraction from oak wood to distillate, as well as the possible correlations between the sugar contents in brandy and its age or the commercial type it belongs to (Solera, Solera Reserva, or Solera Gran Reserva). High-performance anion-exchange chromatography with pulsed amperometric detection was used as the analytical tool to measure the concentrations of glucose, fructose, arabinose, galactose, and xylose, the presence of which in brandy has previously been described.

Alcoholic Beverages↗

PubMed2003

Changes in the polyphenolic and volatile contents of "fino" sherry wine exposed to ultraviolet and visible radiation during storage.

Experiments of accelerated oxidation of "fino" sherry wines have been conducted at 25 degrees C and under the influence of UV-visible radiation (a xenon lamp of 1500 W). With the aim of determining the contribution of UV-vis radiation to the browning phenomenon, two types of glass bottles were employed: topaz bottles (with low values of transmittance in the UV-visible range) and transparent bottles. To identify significant differences between the wine before and after being subjected to the influence of the UV-vis radiation, the values of absorbance at 420 nm and the concentrations of various polyphenolic and volatile compounds were submitted to a multivariate variance analysis. Both factors considered (time and type of bottle) had a statistically significant effect on the values of absorbance at 420 nm and on the concentration of most of the polyphenolic compounds, whereas only the "time" factor was significant for volatile compounds. All wines showed losses in several polyphenolic compounds, which were more severe for the wines bottled in transparent glasses. However, these wines exhibited a lower degree of visual browning (abs 420 nm). In the case of volatile compounds, most of these presented increases during storage exposed to the influence of the UV-vis radiation.

Alcohols↗

PubMed2003

Study of the polyphenol content of red and white grape varieties by liquid chromatography-mass spectrometry and its relationship to antioxidant power.

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.

Antioxidants↗

PubMed2003

Optimisation of headspace solid-phase microextraction for the analysis of volatile phenols in wine.

Headspace solid-phase microextraction has been applied to the analysis of volatile phenols in wine. Silica fibre coated with Carbowax-divinylbenzene was found to be more efficient at extracting these compounds than other fibres such as those coated with polydimethylsiloxane, polyacrylate, carboxen-polydimethylsiloxane, and polydimethylsiloxane-divinylbenzene. Different parameters such as extraction time, temperature of the sample during the extraction, ionic strength and sample volume were optimised using a two-level factorial design expanded further to a central composite design, in order to evaluate several possibly influential and/or interacting factors. The headspace (HS)-SPME procedure developed shows adequate detection and quantitation limits, and linear ranges for correctly analysing these compounds in wine. The recoveries obtained were close to 100%, with repeatability values lower than 16%. The method was applied to a variety of white and red wines.

Chromatography, Gas↗

PubMed2002

Comparison of the evolution of low molecular weight phenolic compounds in typical Sherry wines: Fino, Amontillado, and Oloroso.

Changes in the content of low molecular weight phenolic compounds (hydroxybenzoic and hydroxycinnamic acids, aldehydes, and their esterified derivatives, tyrosol and 5-(hydroxymethyl)-2-furaldehyde) during the aging of three different classes of Sherry wine, Fino, Oloroso, and Amontillado, have been studied. The samples studied were taken from each of the scales of the particular aging system applied to the three classes of wine. Clear differences were observed in the behavior of the low molecular weight phenolic in the three classes of wine. The wines subjected to oxidative aging presented a higher phenolic content overall, with the exception of the esterified derivatives of phenolic compounds that are mainly found in the samples that have not undergone any process of oxidation. MANOVA results confirmed that there are significant differences between all of the samples of the three types of wines. Using LDA, a classification of 100% of the samples has been made.

Aldehydes↗

PubMed2002

Headspace solid-phase microextraction analysis of aroma compounds in vinegar. Validation study.

Headspace solid-phase microextraction (HS-SPME) was evaluated for analysing aromatic compounds in vinegar. The fibre used (a Carboxen-polydimethylsiloxane fibre), and the analytical conditions had been optimised in a previous work. The HS-SPME procedure developed shows detection and quantitation limits, and linear ranges adequate for analysing this type of compounds. The recoveries obtained were close to 100%, with repeatability values lower than 20%. However, considerable differences have been detected between different fibres. The method was applied to a variety of Sherry wine vinegars.

Acetic Acid↗

PubMed2002

Optimisation of headspace solid-phase microextraction for analysis of aromatic compounds in vinegar.

Headspace solid-phase microextraction has been applied to the analysis of aroma compounds in vinegar. Silica fibre coated with Carboxen-polydimethylsiloxane was found to be more efficient at extracting these compounds than other fibres such as those coated with polydimethylsiloxane, Carbowax-divinylbenzene, and polydimethylsiloxane-divinylbenzene, but its repeatability was low. Different parameters such as extraction time, temperature of the sample during the extraction, ionic strength, and sample volume were optimised using a two-level factorial design expanded further to a central composite design. This chemometric tool is very appropriate in screening experiments where the aim is to investigate several possibly influential and/or interacting factors. The extraction efficiency is inversely affected by the acetic acid content-an increase in the acetic acid concentration decreases the extraction efficiency. No interference is observed with the increase in content of polyphenols.

Acetic Acid↗