lunes, 13 de agosto de 2012

Estudios Sobre Tratamientos Alternativos a la Bentonita en el Vino


ESTUDIOS SOBRE TRATAMIENTOS ALTERNATIVOS A LA BENTONITA EN EL VINO

La búsqueda de alternativas a la bentonita para la clarificación de los vinos ha ofrecido recientemente unos resultados muy interesantes. El AWRI (Australian Wine Research Institute) ha estudiado dos nuevas estrategias muy prometedoras para la eliminación de las proteínas de los mostos/vinos.

El AWRI ha demostrado que un polisacárido proveniente de las algas, carragenina, es capaz de eliminar de forma eficaz las proteínas del mosto/vino. Por otro lado se ha observado que la flash pasterización del mosto en combinación con un tratamiento enzimático es capaz de estabilizar los vinos. Con la aplicación de estos dos diferentes tratamientos, el AWRI ha podio obtener vinos que no necesitaban tratamiento de clarificación con bentonita, sin que se produjesen cambios importantes en las características químicas y sensoriales de los vinos tratados.

Más información acerca de estas nuevas soluciones para la prevención de la precipitación de proteínas están disponibles en los siguientes artículos:

Marangon, M., Pocock, K. F., Waters, E.J. The addition of bentonite at different stages of white winemaking and its effect on protein stability. Australian & New Zealand grapegrower & winemaker (580) : 71-73; 2012.

Marangon, M., Lucchetta, M., Duan, D., Stockdale, V.J., Hart, A., Rogers, P.J., Waters, E.J. Protein removal from a Chardonnay juice by addition of carrageenan and pectin. Australian journal of grape and wine research 18 (2) : 194-202; 2012.

Marangon, M., van Sluyter, S.C., Robinson, E.M.C., Muhlack, R., Holt, H., Haynes, P.A., Godden, P.W., Smith, P.A., Waters, E.J. Degradation of white wine haze proteins by a glutamic acid peptidase during juice flash pasteurization. Food chemistry, 42: 1-42; 2012

DEGRADATION OF WHITE WINE HAZE PROTEINS BY ASPERGILLOPEPSIN I AN II DURINT JUICE FLASH PASTEURIZATION

Bentonite is commonly used to remove grape proteins responsible for haze formation in white wines. Proteases potentially represent an alternative to bentonite, but so far none has shown satisfactory activity under winemaking conditions. A promising candidate is AGP, a mixture of Aspergillopepsins I and II.; a food grade, well characterized and inexpensive protease, active at wine pH and at high temperatures (60–80 °C). AGP was added to two clarified grape juices with and without heat treatments (75 °C, 1 min) prior to fermentation. AGP showed some activity at fermentation temperatures (≈20% total protein reduction compared to control wine) and excellent activity when combined with juice heating (≈90% total protein reduction). The more heat stable grape proteins, i.e. those not contributing to wine hazing, were not affected by the treatments and therefore accounted for the remaining 10% of protein still in solution after the treatments. The main physicochemical parameters and sensorial characteristics of wines produced with AGP were not different from controls.

- AGP does not affect the physicochemical wine profile.
- AGP very active in degrading grape proteins, in particular in combination with flash pasteurization.
- The negative perception that practitioners have about heating juice or wine is not supported by scientific data.
- AGP in combination with flash pasteurization can become a viable alternative to bentonite fining in white wines.

More information: http://www.sciencedirect.com/science/article/pii/S0308814612008680

PROTEIN REMOVAL FROM A CHARDONNAY JUICE BY ADDITION OF CARRAGEENAN AND PECTIN

- Backgrounds and Aims:  Bentonite is commonly added to white wines to remove the grape proteins responsible for haze formation. Despite being effective, this technique has drawbacks; thus, new solutions are desirable. The ability of carrageenan and pectin to remove heat-unstable grape proteins, and the impact that such addition has on the physicochemical and sensorial profile of a wine were assessed.

- Methods and Results:  Carrageenan and pectin were added separately or in combination to a Chardonnay juice prior to fermentation. Both adsorbents removed proteins (up to 75%), thus increasing wine protein stability. Carrageenan was more effective than pectin at increasing wine protein stability.

- Conclusions: Pectin and carrageenan removed protein and partially stabilized the samples of the wine.

- Significance of the Study: Pre-fermentation addition of pectin or carrageenan may provide the wine industry with an alternative protein stabilization procedure.

More information: http://onlinelibrary.wiley.com/doi/10.1111/j.1755-0238.2012.00187.x/abstract

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