Baie Dynamic: The ferment over yeast

Monday, 18 May, 2015
Graham Howe
Yeast is the least discussed aspect of winemaking - yet without it, all we’d have is grape juice. Graham Howe discusses the new ferment about yeast and terroir.

Yeast is bubbling to the surface as the hot new issue in wine tastings. At a tasting of new releases by Avondale, one of South Africa’s leading organic and biodynamic wine farms, owner-viticulturist Jonathan Grieve focused on the virtues of natural fermentation - also known as wild or native yeast - as a key aspect of natural winemaking using no enzymes, commercial yeasts, catalyzing agents or softeners.

Corné Marais, winemaker at Avondale, takes up the story: “We harvest a pioneer yeast culture from every block - and handle every block separately. We want to get the expression of Avondale soil into the bottle with minimal intervention. Wild yeast produces great esters - and help to create a more unique, flavourful wine with a good mouth feel. There are hundreds of wild yeasts - whereas commercial yeasts have a singular flavour. We also whole bunch press the wines to preserve natural acidity, use warmer ferments to retain upfront fruit - and age wines on skins in amphorae made from the farm’s clay to develop long tannins.”

Grieve, a passionate advocate of biodynamic viticulture, likes to talk about working with the energy of the land - the natural cosmic rhythms and the microbial life of the soil. Over a tasting of distinctive wines like Anima, Cyclus, La Luna and Samsara, he demonstrates his fervent belief in Avondale’s mantra Terra est Vita (Soil is Life). The stylish labels convey the natural imagery of biodynamic winemaking from whorls, spirals and vortexes to the tree of life. Unlocking the secrets of the soil, “the lively minerals of the land”, the wine tasting is tangible proof of the advantages of organic viticulture. Even if we were tasting on a root day - not the flower (when the wine shows best), fruit or root day.

Yeast was also a talking point at the annual release of new vintage wines by De Krans at the Mount Nelson in early May - which underlined the fact that the Klein Karoo cellar is a producer of top-quality wines as well as ports. Introducing their new “Wild Ferment Chardonnay” 2014 label, winemaker Louis van der Riet - a finalist in the Diner’s Club Young Winemaker of the Year 2014 - commented, “I promised myself ‘If I ever make a Chardonnay again I’m going to do it out of the box. The use of different wild yeasts every year makes each vintage more interesting - the tank tastes different every day. You get more roundness, fullness and flavour in the wine.” 

He laughs about the risks associated with using wild yeast, that fermentation will be incomplete, leaving sugar. “I sat on my knees before the tank and prayed! The Chardonnay is bone-dry and unwooded. We kept it on lees for eight months to add complexity and mouth-feel. Chardonnay is a winemaker’s grape - it’s what you make of it. I’d never try wild yeast on Sauvignon Blanc.” De Krans also launched a maiden MCC - made from Chardonnay (Calitzdorp and Outeniqua grapes), Chenin Blanc and Tinta Barocca, as well as a new Free Run Chenin Blanc 2015. The cellar is renowned for its innovations - a single varietal Tinta Barocca in 1979, SA’s first Touriga Nacional in 2000, Tinta Roriz (aka Tempranillo) the first Moscato and Tritonia, a Calitzdorp blend made from 100% Portuguese varieties. “Honest wines from classic varieties - and no new oak” is Boets Nel’s credo, who exports 70% of his unfortified Portuguese varietal wines grown in the Karoo to enthusiastic markets in Scandinavia.

Abrie Bruwer, the mercurial winemaker at Springfield in the Robertson Wine Valley, was a pioneer of natural ferment with the release of his Wild Yeast Chardonnay in South Africa - earning his new label a cult following since the late 1990s - along with wines such as Méthode Ancienne Chardonnay and Life from Stone Sauvignon Blanc. I recently tasted wines made by Lourens van der Westhuizen of Arendsig, one of the valley’s new generation of winemakers - who specialises in expressing the site-specific terroir of single vineyards in his inspirational batch series. He is another advocate of natural fermentation at Arendsig - and expresses his philosophy widely in the valley as consultant for boutique cellars Mimosa, Sumsaré, Tanagra and Esona.  

Keeping yeast in the spotlight, Peacock Wild Ferment is another new label and logo from Waterkloof, another leading biodynamic wine farm, in Somerset West. Whereas many wines in its Circle of Life and Circumstance range are already fermented without inoculation (or added acid), its new Peacock Wild Ferment Chardonnay, Chenin Blanc, Merlot and Cabernet Sauvignon “advocate the use of ambient yeasts to bring out the natural terroir characteristics in each wine” says winemaker Nadia Barnard. She adds Waterkloof relies only on naturally present wild yeasts during fermentation to allow for the flavours in the vineyard to be expressed in the finished wine.

And at a benchmark vertical tasting of Graham Beck Méthode Cap Classique, Pieter “Bubbles” Ferreira spoke about an ongoing research project which has identified 64 yeast strains in vineyards - to isolate wild yeast strains in a new data base. “Time on the lees is where the real magic lies” he says, “It’s all about the linear development of the yeast. The longer the time on lees, the more reduced the sugar in the dosage”. In a MCC tasting in situ at Beck’s Robertson cellar, winemaker Pierre de Klerk also emphasised how yeast helps to release the secondary flavours in the base wine during bottle fermentation - developing those rich, biscuity, brioche characteristics in bubbly.

“Not too much yeast autolysis is the key to making artisanal, terroir-expressive sparkling wine” added Matthew Copeland - at the launch of Vondeling’s maiden Rural Méthode Ancestral wine, a single-fermented wine made using wild yeast. He commented on “the delicate pearl thread” of this sparkling Chardonnay picked three weeks riper than the usual base wine - “to get a degree of physiological ripeness you can’t get with MCC”, and spent sixteen months on its lees, with zero dosage added.

Last but not least, at a tasting of recent vintages of Nativo’s iconic White and Red Blends, Billy Hughes of Hughes Family Wines, a biodynamic producer in the Swartland, spoke about the use of natural yeast in wine made without the use of pesticides or additives. Ten vintages after his first bottling, Nativo has increased production from 2000 to 20 000 bottles. Hughes spoke about the holistic pyramid of organic, biodynamic and the ideal. His philosophy is “To put the flavour of the farm in the bottle - not the variety”. He concludes, “The organic movement is very dynamic. You can’t necessarily taste the difference in the wine - but you do know that the wines were produced without pesticides or additives. 90% of the work is in the vineyard.”

Yeast was also a talking point at a tasting I attended of award-winning Chardonnay and Pinot Noir at Moorilla winery in Tasmania. Winemaker Conor van der Reest concluded, “We’re moving to wild yeast. Using a proportion of wild yeast is increasingly important - to get more mouth feel and less alcohol conversion.”

Graham Howe

Graham Howe is a well-known gourmet travel writer based in Cape Town. One of South Africa's most experienced lifestyle journalists, he has contributed hundreds of food, wine and travel features to South African and British publications over the last 25 years.

He is a wine and food contributor for wine.co.za, which is likely the longest continuous wine column in the world, having published over 500 articles on this extensive South African wine portal. Graham also writes a popular monthly print column for WineLand called Howe-zat.

When not exploring the Cape Winelands, this adventurous globetrotter reports on exotic destinations around the world as a travel correspondent for a wide variety of print media, online, and radio.

Over the last decade, he has visited over seventy countries on travel assignments from the Aran Islands and the Arctic to Borneo and Tristan da Cunha - and entertained readers with his adventures through the winelands of the world from the Mosel to the Yarra.

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Louis van der Riet, De Krans
Louis van der Riet, De Krans

Avondale
Avondale

Nadia, Waterkloof
Nadia, Waterkloof

Graham Beck
Graham Beck

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