RESUMEN
BACKGROUND: Vitis vinifera L. 'Cabernet Gernischt' grapes from the Yantai wine region of China usually form dense clusters and contain low phenolic content. We applied five concentrations (ranged from 5 to 25 mg L-1 ) of gibberellic acid (GA3 ) to 'Cabernet Gernischt' before anthesis to decrease cluster compactness in two consecutive vintages. Yield indices, grape maturity, and wine phenolic compounds were determined. RESULTS: GA3 application significantly reduced cluster compactness, bunch weight, and yield per vine, but it did not significantly improve fruit ripening. The levels of total phenolics, total tannins, and total anthocyanins in wine were enhanced by GA3 application, with 10 and 15 mg L-1 GA3 treatments consistently producing a significant increase in the concentrations of mavidin, cyanidin, and their derivatives. Specifically, trans-resveratrol was consistently significantly increased by 15 mg L-1 GA3 application. Principal component analysis of phenolic compounds demonstrated the differences among wines produced from GA3 treatment groups and the control. CONCLUSION: Overall, wine phenolic profiles could be significantly modified by application of low concentrations of GA3 before anthesis. Application of high levels of GA3 is not recommended due to significant yield decrease. © 2022 Society of Chemical Industry.
Asunto(s)
Vitis , Vino , Vino/análisis , Antocianinas/análisis , Vitis/química , Fenoles/análisis , Frutas/químicaRESUMEN
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.
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Vitis , Vino , Bebidas Alcohólicas , Odorantes/análisis , Gusto , Vino/análisisRESUMEN
The primary objective of this work was to optimize red wine phenolic prediction with models built from wine ultraviolet-visible absorbance spectra. Three major obstacles were addressed to achieve this, namely algorithm selection, spectral multicollinearity, and phenolic evolution over time. For algorithm selection, support vector regression, kernel ridge regression, and kernel partial least squares regression were compared. For multicollinearity, the spectrum of malvidin chloride was used as an external standard for spectral adjustment. For phenolic evolution, spectral data were collected during fermentation as well as once a week for four weeks after fermentation had ended. Support vector regression gave the most accurate predictions among the three algorithms tested. Additionally, malvidin chloride proved a useful standard for phenolic spectral transformation and isolation. As for phenolic evolution, models needed to be calibrated and validated throughout the aging process to ensure predictive accuracy. In short, red wine phenolic prediction by the models built in this work can be realistically achieved, although periodic model re-calibration and expansion from data obtained using known phenolic assays is recommended to maintain model accuracy.
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Modelos Químicos , Fenoles/análisis , Vino/análisis , Espectrofotometría UltravioletaRESUMEN
This work describes the application of disposable screen printed carbon paste sensors for the analysis of the main white wine oxidizable compounds as well as for the rapid fingerprinting and classification of white wines from different grape varieties. The response of individual white wine antioxidants such as flavanols, flavanol derivatives, phenolic acids, SO2 and ascorbic acid was first assessed in model wine. Analysis of commercial white wines gave voltammograms featuring two unresolved anodic waves corresponding to the oxidation of different compounds, mostly phenolic antioxidants. Calculation of the first order derivative of measured current vs. applied potential allowed resolving these two waves, highlighting the occurrence of several electrode processes corresponding to the oxidation of individual wine components. Through the application of Principal Component Analysis (PCA), derivative voltammograms were used to discriminate among wines of different varieties.
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Antioxidantes/análisis , Técnicas Biosensibles/instrumentación , Técnicas Electroquímicas/instrumentación , Vitis/química , Vino/análisis , Vino/clasificación , Conductividad Eléctrica , Electrodos , Oxidación-Reducción , Análisis de Componente PrincipalRESUMEN
The effect of canopy leaf removal and ultraviolet (UV) on Pinot noir grape and wine composition was investigated in this study. Limited basal leaf removal in the fruit zone was conducted, compared to shaded bunches. The UV exposure was controlled using polycarbonate screens to block UV radiation, and acrylic screens to pass the UV. The results showed that bunch sunlight and UV exposure significantly increased the Brix and pH in the grape juice, and increased substantially wine colour density, anthocyanins, total pigment, total phenolics and tannin content. Bunch sunlight and UV exposure affected terpene alcohols, C13-norisprenoids and other volatile composition of the wine differently. Sunlight exposure and UV resulted in increase of nerol, geraniol and citronellol but not linalool. Sunlight exposure slightly increased the concentration of ß-ionone, but the increase was not statistically significant for UV treatment. Neither sunlight nor UV treatment showed any impact on the concentration of ß-damascenone.
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Frutas/química , Fenoles/análisis , Luz Solar , Rayos Ultravioleta , Vitis/crecimiento & desarrollo , Vino/análisis , Antocianinas/análisis , Color , Frutas/crecimiento & desarrollo , Frutas/efectos de la radiación , Norisoprenoides/análisis , Taninos/análisis , Compuestos Orgánicos Volátiles/análisisRESUMEN
Health benefits of wine, especially with red wine, have been linked to the presence of a wide range of phenolic antioxidants. Thus, the aim of this study was to develop a simple, high performance thin layer chromatographic (HPTLC) method combined with high resolution digital plate images to visually compare multiple wine samples simultaneously on a single chromatographic plate and to quantify levels of gallic acid, caffeic acid, resveratrol and rutin, as representatives of the four different classes of phenolics found in wines. We also wanted to investigate the contribution of the investigated phenolic compounds to the total polyphenolic content (TPC) and total antioxidant capacity (TAC) of the wine samples. The average concentrations of caffeic acid, gallic acid, resveratrol, and rutin in the red wines were 2.15, 30.17, 0.59 and 2.47 mg/L respectively with their concentration below limit of quantification in the white wine samples. The highest concentration of resveratrol and rutin is found in the Cabernet and Shiraz wine samples. The amounts of gallic acid are correlated with TPC (r=0.58). Italian wines have the highest correlation between TPC and TAC (r=0.99) although they do not contain detectable amounts of resveratrol, they contain significant amount of rutin. Therefore, antioxidant properties might be associated with the presence of flavanols in these wines.