Wild yeast fermentation is both an art and a science, and it needs an understanding of both to deliver great results.
It occurs, mostly unobserved, in nature every day (possibly in your fruit bowl) but the two areas we are most interested in are winemaking and sourdough baking.
Like moody teenagers wild yeast needs food and warmth, and a long lie-in. You can gently encourage but you can’t force. And this is where the art comes in. Working with a wild organism to make something incredible – bread; wine – becomes instinctive. How far is too far or not enough?
Oldenburg winery in South Africa’s picturesque Banhoek Valley just outside Stellenbosch, could be described as a shrine to wild yeast fermentation.
Winemaker Nic Van Aarde (whose impressive CV includes stints in Marlborough, Sonoma, Margaret River and China) describes his love affair with the little critters that help him deliver the incredible wines he makes. “With commercial yeast you pour in a packet of the stuff and off it goes. You can sleep at night but ja, it’s for lazy winemakers,” he quips.
Van Aarde’s methods are a finely tuned combination of mad professor and Da Vinci genius, that include rolling his barrels of fermenting wine out into the Banhoek sunshine to warm them up on cold days).
With wild yeast (whether baking or winemaking), time and temperature are key. Too cold and it slows down, too warm and it gobbles all the sugars too quickly with resulting indigestion.
Oldenburg has a laboratory on site – one of the benefits of being a younger estate with owners committed to building for the future – and specialists advising on vineyard solutions to problems that range from leaf-roll virus to foraging baboons and buck that are partial to young vine shoots.
The Banhoek Valley sits strategically between Stellenbosch and Franschhoek and has altitude at the core of its wine climate (around the world, as winemakers seek to mitigate climate change, the cooling effect of altitude is one of the most sought after). Banhoek doesn’t benefit from the ocean winds that cool the Stellenbosch plain and is thus described as Mediterranean, rather than Coastal, so the altitude (and shade from the Hottentots Holland mountain range) is critical. The topography also funnels cool air over the top of the mountain down into the valley at night, lowering high daytime temperatures significantly to deliver the dream of high diurnal range.
Also in its arsenal of wine-making weapons are diverse soils (from granite at the top through crumbly Table Mountain Sandstone in the middle to Alluvial nearer the bottom, with a solid seam of iron-rich ferricrete known in South Africa as coffee stone). The original owner of Oldenburg was a geologist with keen insight into the rocks, soils and minerals that make up the Banhoek terroir. This intel has been put to good use.
For me the standout white wine of the range is the Chardonnay 2022, which spent 11 months in 228-litre French oak with partial malolactic conversion. The oak delivers light seasoning without intruding, the freshness and icy minerality shine through the pale straw liquid, the result is effortless elegance and refinement, a supermodel on the Chardonnay catwalk. A standout aperitif or pair with oysters and fish courses.
The most exciting red is the Cabernet Franc 2021 – a variety Van Aarde says is not for the faint-hearted grower, as results can vary enormously according to soils and climate, but is clearly very happy at Oldenburg. Cab franc has generally been a bit-part player in Bordeaux blends with Cabernet Sauvignon and Merlot but increasingly, where conditions are right, it is gaining a following in its own right.
In a cool year with a long growing season (harvest was delayed by two weeks), the grapes were picked, chilled, sorted, destemmed and left to cold soak for 6-7 days to get the dark, rich colour without extracting too much tannin. A 2-3 week wild-ferment on the skins followed before basket pressing, with the precious free-run juice collected separately. The wine was matured for 18 months in French oak before bottling without fining or filtering. The gentle handling and maceration result in silky smooth tannins, the oak brings warm sweet spices and the result is a power punch of ripe red berry fruit with a hint of fynbos (the fragrant indigenous bush that fills the air with herbal scents and aromatic oils). It is ready to drink now but has great ageing potential.
The Rondekop Rhodium 2020, a Cab Franc-dominant Bordeaux blend with Cabernet Sauvignon and Merlot showcases the warm vintage perfectly, it is aromatic with rich ripe dark fruit and smooth, ripe tannins and hints of white pepper and green leaf. Impressive now but built for the long haul.
The Stone-Axe Syrah 2021 is whole-berry pressed by foot-treading for gentle extraction and fermented in 2nd-fill Austrian foudre and older oak barrels. Smooth, silky and aromatic with great structure and texture, this is a keeper for sure and a great match with spicy food.
With a stated mission of trying to make Cabernet Sauvignon ‘cool’ again (after the flagship South African varietal went through a painful period of heavy oak and tinkering), Van Aarde’s 2020 single-vineyard Per Se from the coffee-stone and granite slopes of Jonkershoek has bright, fresh acidity and light green notes, a food wine to please every fireside sipper.
A hundred thousand years ago Banhoek was known as a place of fear and uncertainty, a ‘scary corner’ of the world where Stone Age man carried axes for protection from predators and enemies. Now it is a peaceful place of warm days and cool nights, where science and art combine to create liquid masterpieces.
You can buy Oldenburg wines in the UK from
Jeroboams
Read more about the archaeology, oral and spatial history of the region here
© Linda Galloway 2023