Natural Fermentation Explained!

Natural Fermentation Explained!

When was the natural wine movement born?

The origins of the movement probably go back to the experiences in the early 1980s of some Beaujolais winemakers who "could no longer drink their own wine." Bored with a taste built for the market, they began to search for more authentic aromas.

Not many people know that a central figure in the birth of the natural wine movement was not a poet but a scientist named Jules Chauvet (1907 - 1989), a fourth-generation winemaker with solid knowledge in chemistry, an expert taster and teacher. He not only talked about natural wine but taught his students how to make wine and left many writings on the subject. The evolution of the movement led to the birth in 2001 of the French association Renaissance des Appellations, then of its Italian branch and later of other groups of winemakers with different rules but accumulated by the same principle: to make wines not homologated by excessive interventions in the vineyard and cellar.

What are just the elements that define a natural wine?

There is no European regulation for natural wines like there is for organic wine, and this determines the fact that there is no clear and unambiguous definition of the term.

For a winemaker to be recognized as a natural wine producer almost always the starting point is his or her organic certification. Subsequently, the producer may decide to join associations of natural winemakers and thus comply with their rules, which may be more or less restrictive. Being part of an association is an easy way to communicate to the public why one has decided to produce different wines. Fairs and events are organized that allow producers to more effectively find new markets.

To identify the basic characteristics of a natural wine, we reviewed the specifications, manifestos and charters of intent of many winemakers' associations5,6,7 and identified the following key points:

The producer's organic certification: while sometimes self-certification is sufficient, others require compliance with limits even lower than organic in the use of copper and sulfur

The absence of any pesticide residue in the finished wine
The sourcing of the majority of grapes from estate vineyards
No mechanical harvesting
Lower maximum limit of sulfur dioxide than in organic wine (sometimes less than half), with the assumption of using it only when necessary
Spontaneous fermentation
Few cellar practices: some associations leave freedom of action to the producer, others even prohibit any kind of filtration and temperature control of tanks. A real challenge for the winemaker! VANs have long been proposing a transparent label, that is, one that shows the full list of a wine's ingredients6.

In Italy, official certification has long been considered, but producers are still very divided on the tools to adopted. In March last year, once again in France, the Syndicat de défense du vin naturel succeeded in obtaining the first recognized certification for natural method wine, defined by a 12-point charter: organic grapes harvested by hand, spontaneously fermented, no additives, no brutal corrective oenological techniques, and no or limited (30 mg/l) sulfur dioxide. Jacques Carroget, spokesperson for about fifty winemakers, explained that the need to establish a clear definition has become increasingly pressing since many producers began calling themselves natural only as a matter of marketing.

The reasons related to the need to reduce the amount of sulfur dioxide in a wine we have already explained here while the benefits of organic vineyard management are clarified in this article. All that remains, then, is to delve into the issue of spontaneous fermentation.

What does spontaneous fermentation mean?

Wine is the product of the microbiological transformation of must by, primarily, yeasts. Needless to say, therefore, the microbial community active during fermentation is primarily responsible for many of its chemical and organoleptic characteristics.

Spontaneous fermentation is the first method of winemaking that has ever been used. It is a low-intervention technique in which yeasts selected for their characteristics (mainly Saccharomyces cerevisiae) are not purchased but those naturally present in the vineyard and winery (Saccharomyces and non-Saccharomyces) are used.

Most non-Saccharomyces cannot withstand the conditions present in the must at late fermentation (presence of alcohol and low levels of oxygen and nitrogen) and are therefore unable to produce an acceptable amount of alcohol10. Consequently, the presence of Saccharomyces yeasts is critical for successful alcoholic fermentation

What are the pros and cons of spontaneous fermentation?

In contrast to fermentation with selected yeasts, the dynamics of a spontaneous fermentation are not easily predictable or reproducible because they are influenced by many variables: weather conditions of the vintage, geographic area, grape variety, harvest and winemaking. The winemaker risks stoppages or stunted fermentations. In addition, the values of some wine parameters (especially volatile acidity, alcohol, and color) may disagree with production specifications.

Nevertheless, the great inter- and intraspecific variety of indigenous microbiological flora results in greater complexity of the final product and yeasts, adapted to specific winemaking conditions, give a distinctive character to wine from spontaneous fermentation. In particular, it seems precisely that the presence of non-Saccharomyces introduces a broader spectrum of aromas and flavors into the wine. Numerous studies have compared the chemical composition of wines from indigenous yeasts and from fermentation with selected yeasts, observing substantial differences. The most significant ones have involved the following descriptors: odor complexity, ripe fruit, herbs and expression of terroir.

Spontaneous fermentation, if accompanied correctly, can enhance the peculiarities of the grape variety, the impact of the terroir and the personality of the producer. Like all other minimally invasive agronomic and oenological methods that characterize the production of natural wines, it can be a difficult choice because intervening less does not always mean doing less.

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