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Phenolic composition of young red wines has been shown to play an important role in their ageing potential. Therefore, the modulation of phenolic extraction during maceration may influence the subsequent phenolic evolution of these wines. The present work aimed to evaluate the impact of three different maceration times on the phenolic levels and evolution observed over time, using spectrophotometric and chromatography methods, and the effect on the aroma, taste, and mouthfeel sensory properties using Projective Mapping. Additionally, grape cell wall deconstruction was monitored during the extended maceration phase by GC-MS and Comprehensive Comprehensive Microarray Polymer Profiling (CoMPP). Our findings demonstrated that longer maceration times did not always correspond to an increase in wine phenolic concentration, although the level of complexity of these molecules seemed to be higher. Additionally, continuous depectination and possible solubilisation of the pectin is observed during the extended maceration which may be influencing the sensory perception of these wines. Maceration time was also shown to influence the evolution of the polymeric fraction and sensory perception of the wines.

[EN] The impact of pre-fermentative cold soak, alone or in combination with dry ice addition, on colour, phenolic and volatile composition of Tempranillo wines at 12 months after bottling was studied. A control wine without cold soak was also evaluated. A sample set consisting of 66 wines was investigated. The results from ANOVA and PCA analysis showed significant treatment-related differences for a number of chemical measurements, as well as overlapping effects. Orthogonal projections to latent structures discriminant analysis (OPLS-DA) of the data showed that the dry ice addition treatment had a major effect on the anthocyanin fraction and on the levels of ethyl decanoate, 2-phenylethyl acetate and decanoic acid. In comparison, the cold soak treatment only had a slight effect on the bisulphite bleaching anthocyanins and volatile composition.

[EN] Background and Aims: The introduction of controlled amounts of oxygen into red wines influences the composition of the phenolic substances and volatiles, and therefore the sensory properties of the wines. The main aim of this study was to evaluate the impact of a simulation of the micro-oxygenation technique through acetaldehyde addition, on colour, and on the composition of phenolic substances and volatiles of Tempranillo wines after 12 months of bottle storage. Methods and Results: The analytical and sensory data were subjected to ANOVA, principal component analysis and orthogonal projection in latent structures discriminant analysis. Addition of acetaldehyde led to an increase in the anthocyanin fraction in coloured form, thus increasing wine colour, together with a change in the composition of the volatiles. Acetaldehyde addition appeared to strongly impact wine ester composition, along with fatty acids and volatile phenols; furthermore, acetaldehyde addition positively influenced the concentration of volatiles. Conclusions: Acetaldehyde addition to red wine caused an increase in the polymeric fraction of the phenolic substances with its corresponding effect on wine colour density and astringency index. Moreover, the volatiles fraction has been better protected during ageing in wines to which acetaldehyde has been added. The acetaldehyde treatment therefore led to a clear difference in the chemical composition of the wines. Significance of the Study: An increase in acetaldehyde in red wines can lead to profound changes in the composition of phenolic substances and volatiles of the wines and may serve as an alternative to oxygen addition in red wines where oxidation is studied., [ES] Se presenta en este trabajo el efecto de la introducción de cantidades controladas de oxígeno en la composición de las sustancias fenólicas y volátiles y, por tanto, en las propiedades sensoriales de los vinos. El objetivo principal de este estudio fue evaluar el impacto de una simulación de la técnica de micro-oxigenación mediante adición de acetaldehído, después de 12 meses de almacenamiento en botella. Se ha podido comprobar que la adición de acetaldehído al vino tinto provocó un aumento de la fracción polimérica de las sustancias fenólicas con su correspondiente efecto sobre la estabilidad del color del vino y sobre la astringencia de los vinos. La adición de acetaldehído afectó también a la composición de los vinos en ésteres, ácidos grasos y fenoles volátiles, estando la fracción volátil mejor protegida durante el envejecimiento en los vinos a los que se ha añadido acetaldehído. Guardar / Salir Siguiente >

[EN] The validation of ultraviolet-visible (UV-vis) spectroscopy combined with partial least-squares (PLS) regression to quantify red wine tannins is reported. The methylcellulose precipitable (MCP) tannin assay and the bovine serum albumin (BSA) tannin assay were used as reference methods. To take the high variability of wine tannins into account when the calibration models were built, a diverse data set was collected from samples of South African red wines that consisted of 18 different cultivars, from regions spanning the wine grape-growing areas of South Africa with their various sites, climates, and soils, ranging in vintage from 2000 to 2012. A total of 240 wine samples were analyzed, and these were divided into a calibration set (n = 120) and a validation set (n = 120) to evaluate the predictive ability of the models. To test the robustness of the PLS calibration models, the predictive ability of the classifying variables cultivar, vintage year, and experimental versus commercial wines was also tested. In general, the statistics obtained when BSA was used as a reference method were slightly better than those obtained with MCP. Despite this, the MCP tannin assay should also be considered as a valid reference method for developing PLS calibrations. The best calibration statistics for the prediction of new samples were coefficient of correlation (R(2)val) = 0.89, root mean standard error of prediction (RMSEP) = 0.16, and residual predictive deviation (RPD) = 3.49 for MCP and R(2)val = 0.93, RMSEP = 0.08, and RPD = 4.07 for BSA, when only the UV region (260-310 nm) was selected, which also led to a faster analysis time. In addition, a difference in the results obtained when the predictive ability of the classifying variables vintage, cultivar, or commercial versus experimental wines was studied suggests that tannin composition is highly affected by many factors. This study also discusses the correlations in tannin values between the methylcellulose and protein pr

[EN] The effect of prefermentative and postfermentative caffeic acid (CFA) addition, prefermentative cold maceration, and a simulation of the micro-oxygenation technique through acetaldehyde addition on the phenolic and color composition of Tempranillo wines was investigated. Cold soaking and dry ice addition were performed as prefermentative techniques. Wines were analyzed after the end of the malolactic fermentation and after 6 and 12 months storage. The results showed an important effect in wines to which CFA had been added, suggesting intramolecular copigmentation reactions through direct interaction between anthocyanins and free phenolic acids, thereby increasing the acylated anthocyanin fraction with an increase in color stability. The higher concentration of total phenols and lower hue values in CFA-added wines also contributed to the stability of these compounds during storage. Prefermentative cold maceration was shown to be influenced by the vintage. Phenolic acids, the acylated anthocyanin fraction, and total phenolics showed higher values in CFA-added and acetaldehyde-added wines. No differences were found in color density between the control wines and both the prefermentative and postfermentative CFAadded wines. However, a higher anthocyanin polymeric fraction and higher acylated anthocyanins, phenolic acids, and total phenols were observed in the CFA-added wines. The implications of this for the color stability of Tempranillo are also discussed.