Lately, natural wines have received considerable attention in the wine media. For example, in February this year, Fairfax Media’s Good Food published two columns in the ‘Milkcrate’ section, one supporting natural wines (bit.ly/2K5H1iJ) and one raising a series of questions, including terminology (bit.ly/2mRnJ7n). This was followed by a two-page summary of a tasting and discussion (bit.ly/2jZpI8i), which at times generated considerable passion in the love/hate camps.

The challenge with the term ‘natural wine’ is to understand what it means to each user. Wine publication Decanter, for example, suggests the term is one of convenience ‘to describe a complex, sprawling ideology that includes organic and biodynamic viticulture, minimal intervention in the winery, and sometimes radical views on sulfur dioxide’ (bit.ly/2AnRXZs and bit.ly/2OuuMiP).

Any broad approach to ‘defining’ natural wines is fraught with difficulty. The viticulture practices of ‘organic’ and ‘biodynamic’, said to be essential in natural wine production, cannot be solely claimed or owned by supporters of natural wine. Both these approaches to vineyard management are widely practised here and in Europe, but most producers would not label their wines as ‘natural’. A good example is Henschke Hill of Grace: this vineyard is under biodynamic management and the 2012 vintage demands about $800 per bottle. Certainly, many grapegrowers aspire to developing a self-sustaining vineyard. The biodynamic approach follows the concepts proposed by Rudolf Steiner. Basing viticulture on the cycles of the moon is an approach that many of my colleagues regard as totally unscientific.

Hand-harvesting and fermentation by indigenous yeasts only are two requirements for natural wines. Indigenous (or ‘wild’) yeasts are found on the skin of the grape and on the surface of any equipment, such as picking buckets, as well as in the atmosphere in the winery environment. Hand-harvesting and fermentation by indigenous yeasts are both widely used in wine production and are not sufficient to distinguish natural wine

per se because many great wines are produced by fermentation with indigenous yeasts. Little is known about how long it takes for a vineyard to produce a stable and consistent microflora that can be reproduced vintage after vintage to give some consistency in the fermentation. Newer vineyards are likely to have an unstable, or changing, microflora population that may not always result in a totally effective fermentation from one vintage to the next.

There are, however, significant differences in production strategy once the grapes have been processed. Additives are not allowed in natural wine production, whereas in most Australian wine production it is common to add tartaric acid to adjust the acidity, because this is claimed to give a more efficient fermentation. Australia’s ancient soils produce grapes that are commonly low in yeast-available nitrogen and so diammonium phosphate may be added to supplement the amount of nitrogen, again to enhance the fermentation. Enzymes, whether pectolytic or flavour enhancing, are not used and tannin addition in red wine production is not part of the natural wine method. Settling the freshly fermented wine prior to bottling is the norm for natural wines, although some are ‘lightly’ (say, 3 µm) filtered.

Perhaps the most contentious issue is the role of sulfur dioxide. SO₂ has a dual role in winemaking – as an antimicrobial agent and as an anti-oxidant. The ‘purists’ in natural wine production will not add SO₂ because it is an ‘additive’: small amounts will be produced in the fermentation anyway, so supplementation through external addition is not performed. Jancis Robinson has noted that the lack of acid addition creates high pH conditions and so the non-use of SO₂ can lead to the growth of non-preferred yeast and bacteria (bit.ly/2NR9dIj). This results in what might be politely called ‘funky’ aromas, but many producers and consumers see this as a positive.

Of course, the non-use of SO₂ is not reserved for natural wine producers – some very expensive wines are produced to meet the demand of those who are allergic to SO₂. Drappier Brut nature sans soufre Champagne is one that comes to mind. The production of this wine actually shows some commonality with the natural wine community (see download at bit.ly/1MTw1PM), even if the term ‘natural’ is not used.

There does seem to be a move towards allowing some SO₂ addition in natural wines. Isabelle Legeron, on her Raw Wine site, includes wines with added ‘sulfites’ up to a total of 70 mg/L in the category of natural, artisan wines. The site links to a long list of wines that meet the low SO₂ requirement as well as satisfying the other requirements for natural wines discussed above.

The reasons for people’s fascination with natural wines would take another column at least to discuss. For some more background on the concept, check out an article on the Wine Australia website (bit.ly/2uXLNKg), which gives an Australian perspective.