Good wine is made from healthy bacteria

Good wine is made from healthy bacteria

Shortly after arriving in Gevrey Chambertin, and keen to discover the wines of Burgundy, I started to ask myself the question: just how is it that the wine made from one plot of vines, can deliver a harmonious and sometimes ethereal melange of cherry and dark berry fruit flavours, with an aftertaste that seems to go on for ever, while the wine from a different winemaker, on the adjoining plot, is flat, lifeless, and lacking any discernibly positive characteristics?

The answer it turns out, is all about bugs, or to be more accurate, bacteria.

An unfortunate consequence of our desire to wage war on ‘germs’, is that the word ‘bacteria’, has come to be associated with something not very nice. Germs however, are only a minor subset, of a vast ocean of healthy and helpful bacteria, which work away 24/7 to perform functions vital to our everyday lives. And they have a determinative role to play, on the quality and taste, of the wine that we drink.

The good bug story starts in the vineyards. Bacteria naturally found in the soils, are responsible for the breakdown of inert matter: they feed on dead leaves, twigs, dead insects, and turn all this autumn detritus into nutrients, which, with the aid some ploughing, and a few friendly worms, are disseminated around the roots of the vines, and absorbed by the plant. However these friendly bacteria, essential to the wellbeing of the plant, can be inadvertently destroyed as the unfortunate side effect of the excessive use of chemicals, used to control a different set of harmful bacteria, those known as odium, and mildew, that attach to the vines, and which flourish in the mild damp conditions that often persist in Burgundy in late Winter and early Spring. When the good soil bacteria has been wiped out by the chemicals, the vines require some other form of food, which is usually provided by the use of more chemicals in the form of an artificial fertiliser. So in a vineyard that has multiple ownerships, one plot can be a natural environment, while the one next to it is an artificial one.

Chapter two of the story, moves to the winery. The grapes in the vineyard have their own set of bacteria, a sort of vineous DNA, which attach to the skin of the grape, and the stems. These bacteria are particular to the plot where the grapes were picked, and left to their own devices, once in the vat with the grapes, they will start the fermentation process, breaking down the sugars in the fruit, and converting the resultant liquid into alcohol. However the use of chemicals in the vineyards destroys not only the unwanted bacteria, but also the friendly ones which trigger the fermentation, which then have to be replaced with a foreign agent. So commercially produced bacteria are introduced to the vat to kick start the fermentation. Does this materially affect the taste of the wine? Well, it is one more step away from the precious association and attachment of the finished product to the vineyard.

And now the action moves back below ground, but this time into the cellar. Here we have yet another complex mix of bacteria, capable of having both positive and negative impacts on what goes into the bottle.

Once the alcoholic fermentation has taken place in the vat, the resultant raw wine is transferred into oak barrels, and moved into cellar storage, where another bunch of good guys trigger a second fermentation of the wine. Bacteria attack the sour tasting malic acid, which is naturally found in the wine, and convert it into the softer, milder tasting, lactic acid, which is an essential part the wines final appeal. On the other hand, some cellars experience an invasion of a wine unfriendly bacteria, called brettanomyces, and once these guys get in, it is the devils own job to get rid of them. They act on the wine in the barrel to produce acetic acid, giving the wine an unpleasant sour taste.

So for the final chapter, we will go back to where the story started, in the vines. For while the negative impact of foreign agents, disrupting what should happen naturally, is all too clear, what remains a complete mystery, is how, when nature is allowed to take its course, the characteristics of the vineyard find their way, via the plant, into the grape, the vat, the barrel, and the bottle. Everyone who has had the privilege to taste Romanee Conti is likely to agree that the wine is a majestic representation of a unique terroir. But even the combined wisdom of the winemakers at this hallowed domaine, will not be able to tell you how it happens. Perhaps it is not such a bad thing, that some bacterial mysteries still remain to be solved.

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