jueves, 12 de julio de 2012

Relación entre los cambios en el contenido de rotundone durante la maduración de la uva y la vinificación para manipular el aroma "a pimienta" del vino


RELACIÓN ENTRE LOS CAMBIOS EN EL CONTENIDO DE ROTUNDONE DURANTE LA MADURACIÓN DE LA UVA Y LA VINIFICACIÓN PARA MANIPULAR EL AROMA "A PIMIENTA" DEL VINO

Caputi, L.; Carlin, S.; Ghiglieno, I.; Stefanini, M.; Valenti, L.; Vrhovsek, U.; Mattivi, F.; Journal of Agricultural and Food Chemistry, 2011, 59 (10) 5565–5571

Se estudió la biosíntesis del sesquiterpeno rotundone en uvas Vespolina durante la maduración durante dos temporadas consecutivas, lo que permitió evidenciar que el compuesto, desde el envero a la vendimia, se acumula y alcanza unas concentraciones bastante altas (de hasta 5.44 µg/kg).

También se observaron unos niveles de rotundone de hasta 1.91 µg/kg en clones Gruener Veltliner, una variedad de uva blanca conocida por dar lugar a vinos con aromas a pimienta. Estas concentraciones son más altas que las encontradas en las uvas Syrah y son parecidas a los niveles que se encuentran en algunas plantas.

Se demostró que el rotundone se acumula casi exclusivamente en el exocarpio de las bayas, lo que indica que la maceración con los hollejos durante la vinificación podría ser utilizada para modular el aroma a pimienta de los vinos tintos.

Sin embargo, el rendimiento en rotundone tras el proceso de vinificación era relativamente bajo. En efecto, sólo el 10% del rotundone presente en las uvas era extraído durante la fermentación, y sólo el 6% se encontraba en el vino en botella.

Los resultados presentados en este trabajo ofrecen conocimientos fundamentales para la manipulación de la nota de pimienta de los vinos con el fin de optimizar la intensidad de este característico aroma.

RELATIONSHIPO OF CHANGES IN ROTUNDONE CONTENT DURING GRAPE RIPENING AND WINEMAKING TO MANIPULATION OF THE "PEPPERY" CHARACTER OF WINE

Biosynthesis of the sesquiterpene rotundone in Vespolina grapes during berry ripening was investigated over two consecutive seasons, revealing that the compound accumulates from veraison to harvest and reaches relatively high concentrations (up to 5.44 μg/kg).

Rotundone levels up to 1.91 μg/kg were also found in clones of Gruener Veltliner, a white grape variety known to give ‘peppery’ wines. These concentrations are higher than those reported for Syrah grapes and are similar to the levels found in some plants.

Rotundone was shown to accumulate almost exclusively in berry exocarp, suggesting that skin contact during winemaking could be used to modulate the peppery character of red wine. However, rotundone yield after the winemaking process was relatively low. Indeed, only 10% of the rotundone present in grapes was extracted during fermentation, and only 6% was recovered in bottled wine.

The results presented in this work provide key knowledge for manipulation of the peppery character of wine in order to optimize the intensity of this characteristic wine aroma.

The sesquiterpene rotundone gives pepper its distinctive aroma. Previously, the aroma of black pepper was attributed to complex interactions of many chemical components, including piperine and related alkaloids that produce a spicy heat sensation in the mouth.

The researchers, led by Alan P. Pollnitz of the Australian Wine Research Institute, in Adelaide, found rotundone not only in white and black pepper but also in marjoram, oregano, rosemary, basil, thyme, and geranium. In addition, they identified the compound as the source of a peppery or spicy aroma in some shiraz wines.

Some aroma testers were able to sniff out the sesquiterpene at concentrations as low as 0.4 ng/L in water and in wine, making rotundone one of the most powerful aroma compounds known. Others were unable to detect the compound even at high concentrations, suggesting that flavor perceptions of wine or ground pepper in food may vary widely among consumers.

More information: http://pubs.acs.org/doi/abs/10.1021/jf200786u

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