WHAT IS..? native yeast
Native yeast: aka ‘indigenous’ or ‘natural’ yeast, or the somewhat prosaic ‘ambient’ yeast; then there’s the decidedly more exotic alias ‘wild’ yeast. Regardless of the moniker, the primary function of these single-cell microorganisms is the same: to transform sugar into alcohol, to make wine from grape juice. However, the actions and consequences, negatives and positives of natural yeast in comparison to those of lab-created, cultured yeast is a mightily complex, intricately threaded debate, for yeast’s role cannot be underestimated – as Andrew Jefford wrote in Decanter’s April 2023 issue: ‘...only yeast can unlock personality and even origin in [grape] must.’ Indeed, it is yeast which triggers, produces and releases much of the flavour and aroma that we associate with varietal character.
In the winery, cultured yeast (the most common species used in winemaking being Saccharomyces cerevisiae) is added straight into grape must, instigating fermentation, whereas with wild or natural ferments, the winemaker opts to wait for native, non-Saccharomyces yeasts – which are found naturally in the vineyard, on the grape and even in the winery – to begin proceedings. Native yeast is lauded for delivering complexity, texture, inherent balance and other, almost intangible site or terroir markers; not to mention, say adherents, avoiding the ‘sameness’ of wines produced on an industrial scale using cultured yeast. However, they are slow and unreliable, opening the window even wider for faults, such as brettanomyces (‘brett’), to scurry in. Inefficiency is another cross to bear, as native yeasts often become redundant above 5% alcohol and require additional cultured strains to finish the ferment – Saccharomyces cerevisiae yeasts are also found naturally on grapes, albeit in tiny quantities.
Natural versus cultured yeast is a kaleidoscopic argument, particularly when considering the perpetual development and fine-tuning of the latter. Yet, despite their undoubted, flighty flaws, the employment of natural yeast, in the right circumstance, is clearly a risk worth taking when winemakers want and are able to make their wine stand out just a shade from the line-up.
It may not deliver a true walk on the wild side, but you’ll more than likely enter a world with a bit of an edge.