Oak Tanks

Summerhill bought itself an early Christmas present... 90 000 L of French oak storage capacity. These nine 10 000 L tanks actually function as both fermenters and maturation barrels.

This is part of winemaker Eric von Krosigk's Biodynamic program. Wood is a natural home for yeast and malolactic bacteria, or in other words, for the micro-biology that transforms grape juice into wine. These beneficial organisms will colonize the wood, and allow us to make consistently delicious wine without relying on packages of winemaking yeasts and bacteria that are made in laboratories. Although there is nothing wrong with the store bought yeasts (in fact, they are a big reason there is so much consistently good quality wine made all over the world these days), there is something almost magical about making wine with your own colony of yeast. The tiny organisms naturalize, and mutate slowly over time, creating a unique formulation that adds complexity and depth to the resulting wine - and importantly, it helps to translate a unique sense of place.

This will also change the style of the red wines made in these tanks vs the 225 L barriques which are currently used for all of our reds. The fruit will be better expressed in these larger vats because of the smaller ratio of oak surface to wine, so that the resulting effect of passive micro-oxygenation is lessened.

Here is a little photo-journal of the process:

The wood and materials arrived on pallets, sent over from Italy. Note the dried reeds used between each plank in order to make the tanks water tight.

We unloaded dozens of huge metal bands.

When the coopers from Italy finally arrived they set right to work...

... and made quick progress.

Soon the tanks were complete and filled with wine. In this image, everything is complete except for the last step of painting the metal bands red. This is done to signify these tanks are used for red wine production. Green bands would signify white wine.

Et voila, we're up and running. Note the red hose leading to the top of the tank. There is a sprinkler up there, and this hose is used to pump the fermenting wines up over the cap of grape skins that forms during fermentation. By pumping over the young wine, we bring much needed oxygen into the fermentation, and extract colour, flavour and tannin from the grape skins.