Proposal of a method for fluorimetric analysis of malvin in red wines

A fluorimetric method for the quantitative determination of malvin (malvidin 3,5-diglucoside) in red wines is described. The method is based on previous fractionation of the wine in a Polyclar AT column and later formation of a fluorophore, by oxidation of the malvin. The proposed method has good precision and accuracy and when applied to hybrid red wines affords results significantly comparable with those obtained by HPLC

Color and Stability of Pigments Derived from the Acetaldehyde-Mediated Condensation between Malvidin 3-O-Glucoside and (+)-Catechin

[EN] A pigment derived from the acetaldehyde-mediated condensation between (+)-catechin and malvidin 3-O-glucoside has been prepared and isolated by semipreparative HPLC, and its characteristics of color and stability have been studied and compared with that of malvidin glucoside in aqueous solutions. When the pH was increased from 2.2 to 5.5, the solution of the pigment became progressively more violet (ìmax ) 560 nm at pH 5.5), whereas similar solutions of the anthocyanin were almost colorless at pH 4.0. This behavior indicated that the anthocyanin moiety of the pigment was more protected against water attack, and thus the formation of its quinonoidal forms was favored. The color of the pigment also showed more stability with regard to bleaching by SO2 than that of malvidin glucoside. Nevertheless, the pigment was more sensitive to degradation in aqueous solution than the anthocyanin. The cleavage of the ethyl bridge that links the anthocyanin and the catechin constituted the first step in its degradation, as demonstrated by the formation of malvidin glucoside as a major product

Color-copigmentation study by tristimulus colorimetry (CIELAB) in red wines obtained from Tempranillo and Graciano varieties

[EN] 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

Land Cover Classification of Complex Agroecosystems in the Non-Protected Highlands of the Galapagos Islands

The humid highlands of the Galapagos are the islands’ most biologically productive regions and a key habitat for endemic animal and plant species. These areas are crucial for the region’s food security and for the control of invasive plants, but little is known about the spatial distribution of its land cover. We generated a baseline high-resolution land cover map of the agricultural zones and their surrounding protected areas. We combined the high spatial resolution of PlanetScope images with the high spectral resolution of Sentinel-2 images in an object-based classification using a RandomForest algorithm. We used images collected with an unmanned aerial vehicle (UAV) to verify and validate our classified map. Despite the astounding diversity and heterogeneity of the highland landscape, our classification yielded useful results (overall Kappa: 0.7, R2: 0.69) and revealed that across all four inhabited islands, invasive plants cover the largest fraction (28.5%) of the agricultural area, followed by pastures (22.3%), native vegetation (18.6%), food crops (18.3%), and mixed forest and pioneer plants (11.6%). Our results are consistent with historical trajectories of colonization and abandonment of the highlands. The produced dataset is designed to suit the needs of practitioners of both conservation and agriculture and aims to foster collaboration between the two areas

Copigmentation of anthocyanins: estimation and influence on the Graciano`s red wine colour

Comunicación enviada al X Congreso Nacional del Color. Valencia 2013Una gran parte del color de los vinos tintos viene explicada por el fenómeno de la copigmentación, sobre todo cuando se trata de vinos jóvenes. Para su estimación el método más usado en la actualidad es el propuesto por Boulton [1], sin embargo este método sólo considera las diferencias de absorbancia a 520 nm y para cuantificar de forma más precisa las diferencias de color que implica este fenómeno se hace necesario considerar el espectro visible entero. En este trabajo se han considerado las dos formas de estimación, considerando las diferencias de absorbancia a 520 nm y las diferencias a lo largo del espectro visible entero (380-770 nm). Se ha observado una sobrestimación de la primera, sobre todo cuando el vino es joven correspondiendo con los porcentajes de copigmentación más elevados. También se ha observado que los parámetros de color están correlacionados con la copigmentación, de tal forma que una mayor copigmentación implica más croma en el vino, menos claridad y variaciones significativas en el tono. Para cada vino, las variaciones en los parámetros cuantitativos de color (claridad y croma) son más altas en la etapa de final de fermentación alcohólica (porcentaje de copigmentación más elevado) que en la etapa de embotellado (porcentaje de copigmentación más bajo). Sin embargo, este fenómeno implica cambios cualitativos (variaciones de tono) más importantes en las etapas finales (embotellado) que en etapas iniciales.It is well known that the copigmentation phenomenon has a large contribution to the red wine colour, especially when it is young. Nowadays, the most commonly used method is the proposed by Boulton which only considers the differences of absorbance at 520 nm. The approach of considering the whole visible spectrum has also been used but is not as well extended as the first one.Differences between the two forms of estimate the copigmentation effect in wines were compared in this study. Moreover, the involvement of this phenomenon in the CIELAB color parameters at two different stages of winemaking was evaluated.Results showed that the method proposed by Boulton seems to overestimate this phenomenon, above all when the wine is young.CIELAB color parameters are correlated with the copigmentation process, thus a higher value of copigmentation implies a higher chroma, a lower lightness and significant variations in the hue. In this way, the variations on the quantitative parameters are higher at the end of the alcoholic fermentation and the variations on the qualitative parameter (hue) are higher when the wine is bottling.Hernández-Hierro, JM.; Rivas-Gonzalo, J.; Heredia, FJ.; Escribano-Bailón, MT. (2013). Copigmentación de antocianos: estimación e influencia en el color de vinos tintos del cultivar Graciano. http://hdl.handle.net/10251/3029

Trying to set up the flavanolic phases during grape seed ripening: A spectral and chemical approach

[EN] Grape seeds were collected in ten different dates and classified in seven groups according to their individual hyperspectral imaging characteristics. Proanthocyanidin composition was studied using HPLC-MS for oligomers and acid catalyzed cleavage for polymers characterization. The combination of both analysis provided a complete description of the flavanols. Chemometric analysis was performed to summarize the analytical results. None of the considered variables presented statistical differences among all groups. From one to five groups were found for each variable, while three was the most frequent value, consequently three putative stages might be considered the real number of different analytical stages since it is the number of statistically significant groups for the majority of the compounds. This classification could be considered as the first step to optimize the use of seeds in winemaking to minimize the gap between sugar and phenolic maturities, consequence of the global climate change, mainly observed in warm climate

Application of differential colorimetry to evaluate anthocyanin-flavonol-flavanol ternary copigmentation interactions in model solutions

The combined effect of anthocyanin−flavanol−flavonol ternary interactions on the colorimetric and chemical stability of malvidin-3-glucoside has been studied. Model solutions with fixed malvidin-3-glucoside/(+)-catechin ratio (MC) and variable quercetin-3-β-D-glucoside concentration (MC+Q) and solutions with fixed malvidin-3-glucoside/quercetin-3-β-Dglucoside ratio (MQ) and variable (+)-catechin concentration (MQ+C) were tested at levels closer to those existing in wines. Color variations during storage were evaluated by differential colorimetry. Changes in the anthocyanin concentration were monitored by HPLC-DAD. CIELAB color-difference formulas were demonstrated to be of practical interest to assess the stronger and more stable interaction of quercetin-3-β-D-glucoside with MC binary mixture than (+)-catechin with MQ mixture. The results imply that MC+Q ternary solutions kept their intensity and bluish tonalities for a longer time in comparison to MQ+C solutions. The stability of malvidin-3-glucoside improves when the concentration of quercetin-3-β-D-glucoside increases in MC+Q mixtures, whereas the addition of (+)-catechin in MQ+C mixtures resulted in an opposite effec

Significado pronóstico y evolución a largo plazo de la frecuencia cardiaca en los pacientes con trasplante cardiaco

[Abstract] Introduction and objectives. The aim of the present study was to examine the prognostic significance of heart rate and its trend in heart transplantation. Methods. This observational study enrolled 170 patients who received a bicaval heart transplant between 1995 and 2005; all were in sinus rhythm. The resting heart rate was determined via electrocardiography at the end of the first posttransplant year and annually until the tenth year. Cox analysis was used to evaluate the incidence of adverse events with a mean (standard deviation) follow-up of 8.9 (3.1) years. The primary study end point was the composite outcome of death or graft dysfunction. Results. The resting heart rate at the end of the first posttransplant year was an independent predictor of the primary composite end point (hazard ratio = 1.054; 95% confidence interval, 1.028-1.080; P < .001) and was significantly associated with total mortality (hazard ratio = 1.058; 95% confidence interval, 1.030-1.087; P < .001) and mortality from cardiac causes (hazard ratio = 1.069; 95% confidence interval, 1.026-1.113; P = .001), but not with graft dysfunction (hazard ratio = 1.028; 95% confidence interval, 0.989-1.069; P = .161). For patients with a heart rate ≥ 105 or < 90 bpm vs those with 90-104 bpm, the hazard ratios of the primary end point were 2.233 (95% confidence interval, 1.250-3.989; P = .007) and 0.380 (95% confidence interval, 0.161-0.895; P = .027), respectively. Heart rate tended to decrease in the first 10 years after transplantation (P = .001). Patients with a net increase in heart rate during follow-up showed a higher incidence of adverse events. Conclusions. An elevated heart rate is an adverse prognostic marker after heart transplantation.[Resumen] Introducción y objetivos. Estudiar la evolución y el significado pronóstico de la frecuencia cardiaca tras el trasplante cardiaco. Métodos. Estudio observacional de 170 pacientes que recibieron un trasplante cardiaco bicavo entre 1995 y 2005; todos estaban en ritmo sinusal. La frecuencia cardiaca en reposo se determinó a partir de electrocardiogramas al final del primer año tras el trasplante y anualmente hasta el décimo año. Mediante análisis de Cox, se evaluó la incidencia de eventos adversos en un seguimiento medio de 8,9 ± 3,1 años. El evento principal del estudio fue la variable combinada muerte o disfunción del injerto. Resultados. La frecuencia cardiaca en reposo, medida al final del primer año tras el trasplante, fue un predictor independiente del evento combinado principal (hazard ratio = 1,054; intervalo de confianza del 95%, 1,028-1,080; p < 0,001). Se observó una asociación estadísticamente significativa con la mortalidad total (hazard ratio = 1,058; intervalo de confianza del 95%, 1,030-1,087; p < 0,001) y con la mortalidad por causas cardiacas (hazard ratio = 1,069; intervalo de confianza del 95%, 1,026-1,113; p = 0,001), pero no con la disfunción del injerto (hazard ratio = 1,028; intervalo de confianza del 95%, 0,989-1,069; p = 0,161). Para los pacientes con frecuencia cardiaca ≥ 105 y < 90 lpm frente a aquellos con 90-104 lpm, las hazard ratio del evento principal fueron, respectivamente, 2,233 (intervalo de confianza del 95%, 1,250-3,989, p = 0,007) y 0,380 (intervalo de confianza del 95%, 0,161-0,895; p = 0,027). Este parámetro presentó una tendencia decreciente en los primeros 10 años del trasplante (p = 0,001). Los pacientes con incremento neto de frecuencia cardiaca en el seguimiento mostraron mayor incidencia de eventos adversos. Conclusiones. La frecuencia cardiaca elevada es un marcador pronóstico adverso tras el trasplante cardiaco