Publications (15)30.4 Total impact
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Article: Formation of Vitisins and Anthocyanin-Flavanol Adducts during Red Grape Drying.
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ABSTRACT: This study evaluated the formation of anthocyanin-derived compounds during the production of sweet red wines from Merlot and Syrah grapes previously chamber-dried under controlled-temperature conditions. The musts from both grape varieties were found to contain pelargonidin-3-glucoside throughout the vinification process. Besides, HPLC-DAD-MS revealed the presence of pyranoanthocyanins in unfermented musts from the raisins. These compounds are adducts resulting from the cycloaddition of pyruvic acid (type A vitisins) and acetaldehyde (type B vitisins) to anthocyanin molecules. The analyses additionally revealed the presence of products of the condensation via a methylmethine bridge between anthocyanins and (epi)catechin, which requires the presence of acetaldehyde. The absence of pyruvic acid, acetaldehyde, and ethanol in the musts from fresh grapes and their presence in those from dried grapes support the idea that these compounds result from enzymatic transformations because the vinification of the musts involves no alcoholic fermentation. The drying process alters the permeability of grape membranes by the lipoxygenase activation effect (LOX), a switch to an anaerobic metabolism and the resulting triggering of the alcohol dehydrogenase enzyme (ADH). The activation of these and several other enzymes confirmed the occurrence of enzymatic transformations and the formation of vitisin A, acetylvitisin A, and the B vitisins of malvidin-3-glucoside, peonidin-3-glucoside, peonidin-3-acetylglucoside, and malvidin-3-acetylglucoside, as well as the adducts Pn-3-glc-methylmethine(epi)catechin, Mv-3-glc-methylmethine(epi) catechin, and Mv-3-acetylmethylmethine(epi)catechin.Journal of Agricultural and Food Chemistry 06/2012; · 2.82 Impact Factor -
Article: Colour correction in white wines by use of immobilized yeasts on κ-carragenate and alginate gels
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ABSTRACT: Pale white wines of the sherry type were subjected to different colour correction treatments based on the use of gel beads consisting of variable proportions of yeasts immobilized on two different polysaccharides (κ-carragenate and alginate). All treatments were found to reduce colour in the control wine, the reduction increasing in a non-proportional way with the increase in yeasts concentration and the decrease in polysaccharide/yeasts ratio. On the same polysaccharide/yeast ratios, κ-carragenate gels proved more efficient than alginate gels. Except for some acids, the concentrations of phenolic compounds were reduced by all treatments (especially those involving κ-carragenate). Based on their colour-correcting ability, moderate retention of human healthy phenolic compounds and similarity to activated carbon in sensory terms, κ-carragenate gels containing a 2g/L concentration of yeasts in a 2:2 polysaccharide/yeasts ratio represent an effective alternative to fining agents traditionally used in the production of white wines.European Food Research and Technology 04/2012; 225(5):879-885. · 1.57 Impact Factor -
Article: Immobilized yeasts in κ-carragenate to prevent browning in white wines
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ABSTRACT: Yeasts immobilized in κ-carragenate gel beads of variable size were used to delay accelerated browning of sherry pale white wines at 35°C. Based on the results, the wines maintained into contact with no gel took 27days to reach the browning limit level for commercial wines of this type (A420 value of 0.180au). However, the wines containing gel beads 1, 2 or 3mm thick reached such a level 24, 30 and 33days later, respectively, than the previous ones. After 27days of contact with gel beads, the wines exhibited decreased contents in phenolic acids, hydroxycinnamic esters and flavan-3-ol monomers and dimers. On the other hand, the yeast gels substantially delayed browning of wines stored at 19°C in bottles for 1year. Thus, while the wine stored without gels reached the commercial rejection limit for A420, those stored in contact with gel beads exhibited virtually no browning and only slight changes in their sensory properties, although they were still acceptable for consumption.European Food Research and Technology 04/2012; 225(2):279-286. · 1.57 Impact Factor -
Article: Influence of aerobic and anaerobic conditions and yeasts on the reaction between (+)-catechin and glyoxylic acid
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ABSTRACT: The reaction between (+)-catechin and glyoxylic acid in wine model solutions was studied under aerobic and anaerobic conditions in the presence and absence of yeasts with a view to determine their contributions to browning of white wine. Under aerobic conditions, the presence of yeasts reduced the production of colored products, the formation rate of which was similar to that observed under anaerobic conditions and in the absence of yeasts. These results reveal that yeasts and intermediate reaction products compete for oxygen. In the absence of oxygen, the production of colored compounds was even smaller in presence of yeasts, as a result of their ability to retain browning products as they form. Because the absence of oxygen not inhibited the formation of intermediate products resulting from oxidation reactions, an alternative oxidation pathway are proposed acting the glyoxylic acid as oxidant. In the usual concentrations of catechin in white wines, the studied reaction of (+)-catechin-glyoxylic acid can contribute significantly to the alteration of the wine color.European Food Research and Technology 04/2012; 222(3):451-457. · 1.57 Impact Factor -
Article: Changes in hydrophilic and lipophilic antioxidant activity in relation to their phenolic composition during the chamber drying of red grapes at a controlled temperature.
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ABSTRACT: The purpose of this work was to study the variation of phenol compounds, as measured by HPLC, during the chamber drying under controlled temperature conditions of red grapes of the Merlot and Tempranillo varieties in relation to antioxidant activity. Both lipophilic and hydrophilic antioxidant activities in these grapes increased during the drying process; the former was measured via proton transfer in the coupled oxidation reaction between linoleic acid and β-carotene, and the second via electron transfer in the DPPH assay. The hydrophilic component was invariably greater in Tempranillo grapes, and so was the lipophilic component in Merlot grapes. Only the increase in hydrophilic antioxidant activity obtained a significant correlation with the phenolic compounds during the drying process. However, based on the phenolic fraction analysis, this result was primarily due to phenolic polymers and, to a lesser extent, also to phenolic acids, flavans, and some flavonols and anthocyans.Journal of Agricultural and Food Chemistry 02/2011; 59(5):1882-92. · 2.82 Impact Factor -
Article: Changes of ochratoxin A in grapes inoculated with Aspergillus carbonarius and subjected to chamber-drying under controlled conditions.
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ABSTRACT: The production pattern for ochratoxin A in grapes inoculated with Aspergillus carbonarius and changes in its concentration during raisining of Merlot, Syrah, Tempranillo, and Cabernet Sauvignon red grapes and Pedro Ximenez white grape were studied. Grapes were chamber-dried under controlled temperature and humidity conditions, with and without dipping pretreatments in alkaline emulsions of olive oil or ethyl oleate. Based on the results for the grapes that developed the fungus (Merlot and Pedro Ximenez), a temperature of 50 °C in the absence of dipping stopped ochratoxin A production and even degraded part of the toxin already formed. Both dipping pretreatments facilitated removal of the toxin and led to its virtually complete disappearance. However, dipping in the ethyl oleate emulsion caused substantial changes in the sensory characters of the musts obtained from the raisins, so it should be avoided to ensure the expected quality in the sweet wines elaborated from them.Journal of Agricultural and Food Chemistry 11/2010; 58(22):11907-12. · 2.82 Impact Factor -
Article: Drying of Pedro Ximenez grapes in chamber at controlled temperature and with dipping pretreatments. Changes in the color fraction.
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ABSTRACT: The drying of Pedro Ximenez grapes in chamber at a controlled temperature of 40 or 50 degrees C is studied. Compared to traditional sun-drying, the chamber-drying shortened the drying time by about 40% at 50 degrees C. In color terms, the musts obtained from grapes dried at 50 degrees C were closer in CIELab coordinates to those obtained by sun-dried grapes, with similar h(ab) values and slightly lower L* and C(ab)*. To shorten further the drying times at 50 degrees C, the grapes were dipped in olive oil or ethyl oleate emulsions containing potassium carbonate. The ethyl oleate pretreatment shortened additionally the drying time by about 25%, providing musts with chroma, lightness, and hue similar to those without grape pretreatment. In general, except for the phenolic compounds corresponding to the drying with ethyl oleate pretreatment, most of these compounds in the remainding conditions studied increased to a lesser extent than expected because of water losses of the grapes during drying, revealing degradation reactions.Journal of Agricultural and Food Chemistry 11/2008; 56(22):10739-46. · 2.82 Impact Factor -
Article: Changes in color and phenolic compounds during the raisining of grape cv. Pedro Ximenez.
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ABSTRACT: Changes in color parameters and phenolic compounds during the sun-drying grape raisining of cv. Pedro Ximenez to obtain sweet wines are studied. Browning increases during the process as a result of the contribution to a greater extent of the low and medium molecular size polymers than the high molecular size polymers. Raisining decreases hue and lightness and increases chroma, all measured as CIELab parameters, indicating a color change to dark reddish hues that is also preferentially due to low and medium molecular size polymers. Most of the phenols studied increase in concentration during raisining, essentially through the concentration effect resulting from the loss of water in the grapes. The concentration changes, however, are comparatively small for hydroxycinnamic esters and flavan-3-ol derivatives, suggesting that these phenolic fractions undergo predominantly oxidative degradation reactions by enzymatic pathways, contributing strongly to the browning of grapes.Journal of Agricultural and Food Chemistry 05/2008; 56(8):2810-6. · 2.82 Impact Factor -
Article: Retention of browning compounds by yeasts involved in the winemaking of sherry type wines.
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ABSTRACT: Wine model solutions were used to study the ability of dehydrated yeasts to retain the brown products formed in the reaction between (+)-catechin and acetaldehyde. Saccharomyces cerevisiae races capensis and bayanus, two typical flor yeasts involved in the biological aging of sherry wines, had a higher capacity to retain coloured compounds than S. cerevisiae fermentative yeast. Of the flor yeasts, capensis exhibited a higher colour reduction capacity than bayanus. Such differences may account for the different rate at which browning compounds are removed at different times of year during the biological aging of wines.Biotechnology Letters 11/2005; 27(20):1565-70. · 1.68 Impact Factor -
Article: Interaction of yeasts with the products resulting from the condensation reaction between (+)-catechin and acetaldehyde.
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ABSTRACT: The condensation reaction between (+)-catechin and acetaldehyde was studied in model solutions in the presence and absence yeasts in order to evaluate its contribution to color changes in fermented drinks such as white wine. On the basis of the results, the yeasts retain the oligomers produced in the reaction, their retention ability increasing for higher polymerization degrees. As a result, the color of model solutions, measured as the absorbance at 420 nm, was found to decrease after the addition of yeasts. On the other hand, the yeasts exhibited no inhibitory effect on the condensation reaction, which took place at the same rate in their presence and absence. At acidity levels and reactant concentrations similar to those in wine, with acetaldehyde in high concentration as it is present in sherry wines, the reaction was found to occur very slowly. Taking into account that Yeasts are present during most of the winemaking process; consequently, they retain oligomers, and the studied reaction could mainly contribute to the alteration of the color of white wine after bottling.Journal of Agricultural and Food Chemistry 05/2004; 52(8):2376-81. · 2.82 Impact Factor -
Article: Adsorption of phenolic compounds and browning products in white wines by yeasts and their cell walls.
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ABSTRACT: Dehydrated yeast cells at variable concentrations were used as fining agents to decrease the color of white wines with two different degrees of browning (0.153 and 0.177 au, measured at 420 nm). Both wines showed a linear decrease of browning with increasing yeast concentration. However, in terms of efficiency, the yeasts exhibited a higher color lightening at greater concentrations acting on the darker wine. This suggests a preferential retention of some types of yellow-brown compounds that could increase their concentrations at the higher degree of browning. To confirm the role of yeast cell walls in the retention of browning compounds and to evaluate their potential use as fining agents, they were applied at variable concentrations to a browned wine (0.175 au). The cell walls were found to be the active support for the adsorption of browning compounds, but their efficiency was much lower than that of an equivalent amount of the yeast cells from which they were obtained. Finally, HPLC determinations of low-molecular-weight phenolic compounds showed flavan-3-ol derivatives to be significantly retained by both yeasts and their cell walls.Journal of Agricultural and Food Chemistry 01/2003; 50(25):7432-7. · 2.82 Impact Factor -
Article: Yeast-induced inhibition of (+)-catechin and (-)-epicatechin degradation in model solutions.
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ABSTRACT: (+)-catechin and (-)-epicatechin degradation in water-alcohol solutions containing Fe2+ and tartaric acid was studied in the presence and absence of yeasts. On the basis of the results, yeast partially inhibited the degradation of both flavans, with much slower formation of browning products absorbing at 420 and 520 nm. In comparative terms, yeast was found to be more efficient toward the degradation products of (+)-catechin absorbing at the latter wavelength. Likewise, the presence of yeast decreased the yield of a group of colored compounds eluting at high retention times in HPLC and indicated these as important contributors to color darkening in white wines. This inhibitory effect may in part account for the resistance to browning observed over periods of several years in sherry wines subjected to biological aging under flor yeast.Journal of Agricultural and Food Chemistry 04/2002; 50(6):1631-5. · 2.82 Impact Factor -
Article: Comparative study of browning and flavan‐3‐ols during the storage of white sherry wines treated with different fining agents
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ABSTRACT: White sherry wines were treated with three fining agents (activated charcoal, PVPP and Riduxhigh), in addition to an initial treatment with casein and bentonite, in four different combinations. The wines were stored at 20 or 30 °C for 1 year with a view to examining changes in their flavan-3-ol fraction and differences in their degree of sensitivity to browning. Flavan-3-ol monomers and dimers, as well as browning measured as absorbance at 420 nm, increased during storage in all the wines. After this period the wines treated with fining agents containing activated charcoal, PVPP and Riduxhigh exhibited less marked browning, with no significant differences among them at both 20 and 30 °C. However, taking into account the higher initial colour of bottled wines treated with Riduxhigh in relation to those treated with activated charcoal or PVPP, this fining agent showed higher capacity to control browning.© 2000 Society of Chemical IndustryJournal of the Science of Food and Agriculture 01/2000; 80(2):226 - 230. · 1.44 Impact Factor -
Article: Changes in phenolic compounds and colour in pale Sherry wines subjected to fining treatments
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ABSTRACT: Changes in the concentrations of hydroxybenzoic acids, hydroxycinnamic acids and their esters, monomeric and dimeric derivatives of flavan-3-ol, and flavonols, as well as in the UV-visible absorbances of pale Sherry wines were studied. The wines were subjected to four different fining treatments: casein + bentonite, casein + bentonite + activated charcoal, casein + bentonite + polyvinylpyrrolidone (PVPP) and casein + bentonite + Riduxhigh. Based on the results, the treatments including activated charcoal and PVPP were the most effective at decreasing the overall concentration phenolic compounds, with no significant difference between them. Likewise, these treatments provided the best results in relation to wine colour in the visible spectral region, and particularly at 420 nm, at which wavelength browning compounds are usually measured.Zeitschrift für Lebensmittel-Untersuchung und -Forschung 04/1997; 205(6):474-478. -
Article: Yeasts used to delay browning in white wines
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ABSTRACT: Commercial white wines of the Sherry type were subjected to accelerated browning at 35 °C in the absence and presence of yeasts at concentrations of 1, 1.5 and 2 g/l. Based on the results, the yeasts delayed browning in the wines, measured in terms of the absorbance at 420 nm, the effect increasing with increase in the yeast concentration. The addition of yeasts was also found to affect phenolic compounds, particularly decreasing the concentrations of brown compounds. Wines of the same type stored in stoppered bottles at 19 °C for 12 months exhibited a considerable delay of browning in the presence of yeasts with not-too-serious alteration of their sensory properties, which made them still acceptable for consumption.Food Chemistry.
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Institutions
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2002–2012
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Universidad Católica de Córdoba
Córdoba, Provincia de Cordoba, Argentina
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1997–2012
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University of Cordoba (Spain)
- • Departamento de Química Agrícola y Edafología
- • Facultad de Ciencias
Córdoba, Andalusia, Spain
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