Although wine is made by winemakers, in fact, what really turns grapes into wine is the tiny saccharomyces cerevisiae , which are the most critical microorganisms in winemaking, which can be the selective yeast added by the winemaker into the wine tank, but also the native yeast that is originally attached to the grape skin.
Potential Saccharomyces cerevisiae species in the natural environment are so diverse, with their own specialties and characteristics, that natural winemakers often choose to compete with each other and relay alcohol fermentation.
It seems natural and natural, and it takes no effort to obtain it, but the existence of microorganisms in the environment is not for the purpose of winemaking, grapes as food, wine is actually a by-product of the survival and metabolism of microorganisms in large quantities. Life always has its own process and way out, to accompany hundreds of millions of microorganisms to dance together, to make delicious wine, not only is it not easy, in fact, it is full of many unknowns and dangers.
Brettanomyces bacteria (often referred to as brett), which makes winemakers nervous, is also a kind of yeast, and it is not known as wine yeast for irony, which often makes the wine produce a rustic smell, such as the smell of walking into a horse cellar. Some may like it, but for winemakers, it's a source of pollution that must be removed.
Maintaining the hygienic environment of the wine cellar and minimizing the old wooden barrels that allow bacteria to hide in these containers can indeed be improved, but these yeasts are also stored on the grape skin, and the use of sulfur dioxide to suppress the wine yeast is a method that many winemakers will adopt, in addition to bacteriostatic, sulfur dioxide can also be antioxidant, is a fairly versatile winemaking additive.
However, after addition, it will also affect the vitality of many microorganisms, including native yeast, and even reduce the tolerance of wine to oxygen in the future.
Adding or not adding, how much to add, when to add, whether it is natural or not, is an important decision when brewing wine, because it is difficult to have a standard answer when it is involved with a large number of microorganisms. Adding may solve problems temporarily, but it may also create more new problems.
Before talking about the naturalistic rat-smell crisis, this is the premise that needs to be understood most. If you don't care much about the development of naturalism, you can ignore this article, although it is not completely guaranteed, but usually adding enough sulfur dioxide inhibits the vitality of microorganisms, and it is easy to avoid the taste of rats.
The greatest fear is not brewing failure, but the unpredictable unknown. The biggest concern of natural winemakers in recent years is not oxidation, not volatile acids, not bouquet yeast infections, but unpredictable, unpredictable rodent smells.
The rat smell in the wine sounds sensational and unappetizing, but in fact, like the smell of sauvignon blanc's cat urine, the source is completely unrelated to animals, and it is not necessarily completely annoying.
When I was a student in France 26 years ago, this smell was named after peanuts in class, which is actually similar to the aroma of popcorn or cornflakes, which is more commonly used in English, and some people think that it is the aroma of basmati rice or cheese crackers.
Although wine fans don't necessarily hate it, and even some people prefer it, winemakers mostly don't want to appear in their own wines, because when it is serious, it may really turn into a strange smell reminiscent of a rat cage, and now goût de souris (rat taste) has become an official tasting term.
Even though winemakers already know that the source of these odors is produced by certain microorganisms in wine during metabolism, such as the lactic acid bacteria lactobacillus hilgardii, and even know that four molecules such as 2-acetyl-3, 4, 5, 6-tetrahydropyridine are the main sources of these odors, what really worries winemakers is that these tiny molecules, although already present in wine, are not necessarily detectable most of the time.
First, because these molecules are not volatile in the acidic environment of the wine, it is completely insensible to smell with the nose alone, and the wine must be swallowed, so that the acid value is close to the neutral saliva in the diluted mouth after the residual wine is diluted, so that the sour taste is reduced, and it is possible to perceive. But at the same time, it also depends on the temperature and oxidation of the wine, as well as other reasons that are still unknown.
This means that it may not be discovered until some time after the bottling is on the market, and even the same batch of wine may appear in only a part of the bottle; it often disappears after months of cellaring; and it is often opened for several hours before it can be drunk. But to complicate matters further, about 30 percent of people don't perceive these aromas, and if the winemaker happens to be the lucky 30 percent, it's even harder to control these annoying smells.
Even though this smell has been experienced in some aged spirits, in recent years it has almost only been drunk in natural wines. The absence or addition of very small amounts of sulfur dioxide is the most critical reason why murine aromas are becoming more common. But even so, there are a lot of wines that are unprotected by added sulfur dioxide and are completely uncontaminated by the smell of rats.
In the last four years, hundreds to thousands of naturalistic wines have been intensively tasted each year, and about 10% of the wines have suspected odors, of which less than half are serious enough to affect the tasting, and most of them are encountered during barrel-side tastings.
In addition to relying on good luck, natural wines with high acidity and particularly low acidity can often avoid such troubles, and natural winemakers who strive to maintain a clean cellar and strict selection are also less likely to have this problem.
Many wine critics cannot understand, knowing that there is a risk but insisting on not adding it, questioning whether it is the dogmatism of anti-sulfur dioxide. As an advocate and enthusiast of naturalism, I also dislike the scent of rats that remains deep in my throat, and my tolerance is even much lower than that of oxidation, volatile acids, and the smell of brett bacteria infection, and I am obviously not in that lucky 30%.
But I think the problem of rat smell can only be solved with sulfur dioxide is also another kind of dogmatism, although this may be the most convenient and simple solution.
As mentioned at the beginning, the addition or absence of sulfur dioxide may be important, but for some natural winemakers, how to view peaceful coexistence with microorganisms and find ecological balance in the wine tank may be even more critical.
Habitual reliance on protective nets is a safe guarantee, but it can also be a barrier closer to the real world, and the rat smell in the wine is one of the possible costs of trying to get out of the protective net. As for drinking or not drinking, it depends on whether it is the 10% evil or 90% good.
About the columnist
Lin Yusen
(Wine and Food Writer)
Lin Yusen graduated from the Department of Philosophy of Tunghai University and the Master of Wine Economics and Management in Paris. Recognized as the best wine writer in the Chinese-speaking world.
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