Once the harvest starts drawing to a close, the cellar is at the point where tens of thousands of litres of juice – in various stages of fermentation and post-fermentation processing – needs to be dealt with, processed and stored to complete the journey into a bottle of Rondekop, Oldenburg Vineyards or <CL°. This month, we are taking a closer look at the different types of vessels that will be home to this precious liquid, and what each vessel brings to the process of turning juice into wine.
Most of our wines begin their journey in stainless steel tanks. Stainless steel is inert, so nothing is imparted into the wines, and no oxygen comes into contact with the wine. Importantly, the temperature can be controlled on the stainless steel tanks – Nic uses them for his cooler ferments, through the built-in cooling system (cooling jackets) which allows him to set the tank temperature down to the desired °C (normally 16°C for white wines). White wines fermented in stainless steel have a fresh, crisp character to them.
Next we have the concrete eggs – a relatively new addition to the Oldenburg Vineyards cellar. These are used both for fermentation and storage. Concrete is semi-permeable, meaning the concrete permits oxygen to permeate the vessel in tiny amounts (micro-oxygenation), which allows the wines to develop a softness but without the flavours that can be imparted by oak. Our Chenin Blanc is fermented in the concrete eggs. While the eggs are situated in one of the cooler barrel rooms (15°C), the eggs themselves have no cooling system so the fermentation runs slightly warmer, peaking at 22-23°C. Wines fermented in concrete often show a lovely minerality, and these wines are used in our <CL° White Blend, as well as our Chenin Blanc. Nic will also be using the eggs to store some Syrah in, for the micro-oxygenation effect but without the oaking effect, for a fresher and brighter component.
Our foudres (a combination of Austrian and French oak) have been used since 2020 for the fermentation of Chenin Blanc. We have four foudres, one of which is temperature controlled – used to ferment cold at 16°C. Two of the foudres are also used to age Syrah. The main characteristic of the foudre is the ratio between volume and surface area, which means you get less of an oaking effect, but with the micro-oxygenation effect. Nic prefers a light touch with wood on Syrah, so the foudres offer him the perfect balance.
Lastly we also have a number of 225 L barrels, used mainly for our Bordeaux varietals. These barrels have a smaller surface to wine ratio, and give a more pronounced oaking effect to the wines inside. Nic uses new oak, 2nd and 3rd fill for the Bordeaux varietals. Syrah is aged in older oak, 300 and 500 L barrels, with no new oak used. For Chardonnay, he uses 228 L toasted Burgundian coopers, split between one third each new oak, 2nd and 3rd fill. Chardonnay is both fermented and aged in the barrels. Some Chenin Blanc is also fermented in oak barrels, but only older 300 L ones – no new oak is applied.
Clearly, the choice of vessel has a significant impact on the type of wine being created. Nic is employing each vessel to the benefit of the wine, style and quality we are striving for.