“Large egg-shaped vessels have been appearing in increasing numbers at high end wineries on the West Coast, stirring a mixture of bafflement, warm, return-to-the-womb associations and fears of an alien invasion…” Field Maloney, Wine & Spirits, February 2009

Very funny intro. Alien invasion is exactly what describes the image that went through my head when I saw these egg shaped tanks for the first time. I immediately thought of the 1993 movie: Coneheads, hence the image.  From the moment I saw a picture of these tanks – and I must embarrassingly admit it was only last year – I have wanted to investigate this amusing (to me) new movement in winemaking. It looks rather funny in a cellar. It looks like a giant hatchery where large prehistoric flying reptiles are about to emerge from any second.

The tanks are made from concrete and they are in an egg shape. Why the concrete? Well apparently concrete allows for a micro oxygenation effect on the wine like barrels do, except without adding wood flavors. Why the egg shape? It apparently creates a vortex in the wine and allows for lees to stay in suspension so stirring is not necessary. Lees in suspension has various advantages, hence the practice of batonnage.

The mastermind behind these tanks is Marc Nomblot who on request of biodynamics winemaker, Michel Chapoutier, built the first one in 2001. This caught on quickly and to use the the description of Jeffrey Iverson, these egg shaped tanks are now “hatching in wineries all over the world.”

I recently visited the hatchery of Boekenhoutskloof winery in Franschhoek, South Africa (yes the eggs have reached the southern tip of Africa). They ferment Grenache blanc in their eggs. They start fermentation in stainless steel tanks on skins, so no settling, and press anywhere from 25 – 50% into the fermentation. The must is then pumped with all its lees into the eggs. Fermentation is conducted at 16 – 18°C; they use a coil for cooling (Franschhoek is a tad warmer than the Rhône). The coil only goes into the egg for about an hour at a time. These concrete eggs are great insulators, compared to stainless steel that is conductive. Fermentation is about seven to ten days with Lalvin ICV-GRE yeast (Lallemand). After fermentation the wine stays in the eggs for 10 months. To the winemaker the biggest attribute from using the eggs is the incredible mouthfeel one can obtain this way.  This Grenache blanc forms part of of a white blend called Wolftrap white. Even though Boekenhoutskloof is not a biodynamic winery they do embrace some of the principles, such as these egg tanks, and plan to expand their hatchery on an ongoing basis. They have also started to expand the usage to other grape varieties.

So certainly with “biodynamic”, “natural” and “non-interventionist” winemaking being the buzz words at the moment, I reckon these eggs are here to stay for a while. Personally I believe in interventionist winemaking, but here is a concept that even makes sense to me. I’m just not so sure about racking during certain moon cycles though. ..

Boekenhoutskloof winemaker Jean Smit and some of their eggs.

Karien O’Kennedy is the Online Communications Manager for Oenobrands and knows the odd thing or two about fermentation and winemaking.