Artículos (Nutrición y Bromatología, Toxicología y Medicina Legal)

URI permanente para esta colecciónhttps://hdl.handle.net/11441/26073

Examinar

Mostrando 1 - 3 de 3

Color-copigmentation Study by Tristimulus Colorimetry (CIELAB) in Red Wines Obtained from Tempranillo and Graciano Varieties
(Elsevier, 2013) García Marino, Matilde; Escudero Gilete, María Luisa; Heredia Mira, Francisco José; Escribano Bailón, María Teresa; Rivas Gonzalo, Julián Carlos; Universidad de Sevilla. Departamento de Nutrición y Bromatología, Toxicología y Medicina Legal; Comisión Interministerial de Ciencia y Tecnología (CICYT). España
A study of the changes of copigmentation phenomenon in wines elaborated from different varieties has been undertaken. Colorimetric measurement of Tempranillo (T) and Graciano (G) monovarietal wines, and two 80:20 blend wines: M, (grape blending T and G, co-maceration) and W (wine blending T and G, co-vinification) was performed by spectrophotometry. Significant differences (p<0.05) were found among the color of the wines. The Graciano cv. afforded somewhat darker and more colorful wines than the other wines. The color difference values, δE*ab suggested that co-vinification (W) led to wines being more similar to T than the co-maceration (M). The δE*ab[w-c] between untreated wines - whole wines, w - and the wines diluted to eliminate copigmentation - corrected wines, c - was 14.2 CIELAB units in the initial stages of winemaking and 6.7 in the final stages. M had a greater proportion of color due to copigmentation than the monovarietal wines. Evaluation of this parameter confirms the importance of copigmentation process into wine color during the early stages of the vinification. Also, through the full spectrum, quantitative data obtained allow a visual interpretation of the changes involved. In addition, with the aging in bottle, M wines had more stable color and more different color than W wines.
Colorimetric characteristics of the phenolic fractions obtained from Tempranillo and Graciano wines through the use of different instrumental techniques
(Elsevier, 2012-06-30) García Marino, Matilde; Escudero Gilete, María Luisa; Escribano Bailón, M. Teresa; González-Miret Martín, María Lourdes; Rivas Gonzalo, Julián Carlos; Heredia Mira, Francisco José; Universidad de Sevilla. Departamento de Nutrición y Bromatología, Toxicología y Medicina Legal; Comisión Interministerial de Ciencia y Tecnología (CICYT). España
The aim of the present work was to determine whether there is any relationship between measurement by transmission and reflection (in the latter case, with and without contact with the sample). We also evaluated which methodology used would offer a better interpretation of the results in visual terms. For this purpose, different colorimetric techniques such as transmission spectrophotometry, diffuse reflectance spectrophotometry and spectroradiometry were applied. The samples consisted of increasing dilutions (0, 20, 40, 60, 80 and 100%) of the phenolic fractions obtained from 4 wines: Tempranillo (T) and Graciano (G) monovarietal wines, and two 80:20 mixtures: M (wine elaborated by blending grapes) and W (a blend of the T and G wines) (9 fractions per wine). Fractionation was performed using gel permeation chromatography with a Toyopearl HW-40S column, and the dilutions of the fractions were performed with synthetic wine (pH=3.6). The spectroradiometric measurements permitted the differences due to the dilution effect on the fractions to be established more clearly than with the results obtained using diffuse reflectance and spectrophotometry. Thus, this technology is very suitable for use in comparative interpretations by the human eye. In turn, we assessed the changes in colour due to the effect of dilution on the fractions, observing that the effect of dilution led to an increase in the values of lightness (L *), while the chroma values (C * ab) followed the opposite trend, in agreement with its role as a variable related to chromatic intensity or vividness of the sample. In contrast, hue (h ab) did not seem to be affected by dilution of the fractions, in consonance with the qualitative nature of this parameter.
Colorimetric study of the interactions between different families of red wine pigments using transmittance and reflectance measurements
(Elsevier, 2013-01) García Marino, Matilde; Escudero Gilete, María Luisa; Escribano Bailón, María Teresa; González-Miret Martín, María Lourdes; Rivas Gonzalo, Julián Carlos; Heredia Mira, Francisco José; Universidad de Sevilla. Departamento de Nutrición y Bromatología, Toxicología y Medicina Legal; Comisión Interministerial de Ciencia y Tecnología (CICYT). España
The aim of this work was to conduct a detailed colorimetric study, using transmittance and reflectance measurements, to evaluate the possible interactions occurring among the different families of pigments comprising to colour matter of red wines and their contribution to the colour in aged red wines.To accomplish this, the phenolic material of monovarietal red wines obtained from Tempranillo and Graciano varieties, and their blends, were fractionated by gel permeation chromatography in order to separate the coloured fractions with different chemical compositions. The binary blends at different concentrations of the fractions having higher anthocyanin monoglucoside proportions with fractions having higher pyranoanthocyanin derivative contents and direct flavanol-anthocyanin condensation products were carried out in order to determine the effect of adding these derivatives on the colour of the anthocyanin monoglucosides, the major wine pigments. It was observed that the addition of derived pigments to the anthocyanin monoglucosides fraction resulted in colour differences perceptible by the human eye. These variations were mainly quantitative (changes in chroma and lightness), and were also qualitative (changes in hue) in monovarietal wines.Studying the phenolic fractions of wines implies an approach to the chemical reality of the wines, more than the studies on model solutions, since they can lead to the knowledge of those components having more influence on the final colour of the wine. With these results the wineries could conduct the vinifications towards a higher extraction of the components or families of components more important for the intensity and stability of colour.

Examinar

Examinando Artículos (Nutrición y Bromatología, Toxicología y Medicina Legal) por Agencia financiadora "Comisión Interministerial de Ciencia y Tecnología (CICYT). España"