The Individuality of Taste: Bacteria in Your Mouth Affect the Aroma of Wine, Study Says

aroma of wine

A new study has found that bacteria in the mouth can impact the aroma of wine on first taste. Photo Credit: Wikimedia Commons user William Lawrence


In a wine tasting, your nose isn’t the only tool you have to test a wine’s aromatics. A small study sponsored by Spain’s Institute for Scientific Research found that the bacteria in your mouth actually has a huge impact on the aroma of wine. Researchers discovered that when bacteria in our mouths comes into contact with chemical compounds in wine, gas molecules are produced and detected in the olfactory center near the back of our throats. As wine drinkers taste the wine on their tongues, they also smell new aromatics in the wine that were produced when the wine came into contact with common mouth bacteria. The study suggests that bacteria plays a central role in wine tastings, and that it can mean the difference between hating and loving a wine on first taste.

How the Mouth “Smells” Wine

A common misconception is that taste buds in the mouth are solely responsible for our sense of taste, while our nasal passages are solely responsible for our sense of smell. In fact, our bodies are equipped with a third perception tool: the retronasal passages. This is the dime-sized patch of nerves in the back of the throat that combine taste with smell to produce entirely new flavors and sensations. To test the theory that retronasal passages rely on bacteria to chemically alter the scent of wine in the back of the throat, Spain’s researchers isolated common types of mouth bacteria like Staphylococcus aureus, Enterococcus faecalis, and Streptococcus oralis. When these bacteria mix with the chemicals in wine from the Spanish Verdejo grape, new compounds are produced that change the way tasters perceive the wine in the back of the throat; when the bacteria is altered in any way, the chemical process is interrupted and the aromatics change.

The study was very small, using just 22 volunteers, but researchers were able to measure differences between the control group (which consisted of eight people) and the test group (of 14 people). After taking bacterial samples from the mouths of the volunteers, the researchers added Verdejo grape extract to the samples, noting that in the test group, different gas molecules were released depending on the type and number of bacteria in the test sample. In other words, when researchers altered the bacteria, the aromatics released by the wine extract physically changed. Spain’s institute is currently working on further studies to prove this observation.

Personal Taste Really Is Everything  

The number and type of chemical compounds released when bacteria came into contact with wine varied greatly depending on the volunteer’s natural bacteria. Like fingerprints, our bacteria levels depend on a host of genetic factors. As one of the study’s researchers, Maria Victoria Moreno-Arribas, observed, “This was the most interesting conclusion of our study — the fact that there is a huge individual component to all of this, that each individual’s oral microbiota is as unique as human gut microbiota.” Researchers also point out that wine drinkers can change their natural bacteria depending on what they eat and whether they have brushed their teeth recently.

This lends validity to the idea that every wine critic experiences taste differently, explaining why two wine critics can have such vastly differing opinions on the same wine. For example, Wine Advocate’s Jay Miller described the nose of the 2004 Pingus as heavy in cedar, charcoal, and blackberry with an overall smokiness. International Wine Cellar’s Josh Raynolds also found notes of dark berries and smoke in the nose, but he smelled more subtle aromas of vanilla, sandalwood, and minerals. In another example, Wine Advocate’s Robert Parker went toe-to-toe with International Wine Cellar’s Josh Raynolds on a classic Rhône blend known for having a strong bouquet. In the 2005 Chapoutier Chateauneuf du Pape Barbe, Parker found “huge aromatics” of pepper, lavender, and red berries. By contrast, Raynolds found gamey aromas that were strong in dark red berries, but made no mention of pepper or flowers. What these examples tell us is that even professional wine critics have unique opinions on the taste and aroma of wine that may very well stem from differences in the bacterial makeup of their mouths.

Jancis Robinson has long supported individualism in wine tastings. She once said, “Almost anyone can be a wine taster; all it takes is a will and a nose.” She goes on to explain that genetics aren’t the only factor in a person’s tasting ability; certain foods or even late life injuries can impact the way someone tastes a wine. Especially as people age, the olfactory senses in the back of the throat becomes more dull, meaning that some older tasters can no longer pick out subtle aromas in wine. According to her observations and this new study, the slightest change in a person’s sense of taste or smell can mean the difference between rating a wine 90 points and rating it 95 points.

Refine Your Palate

Now that you know how easy it is for your sense of taste to fade or change, what can you do to protect your senses? Hawk Haven Vineyard suggests starting with a clean workspace, meaning no added smells. Wine tasters should avoid wearing perfume or cologne before a tasting. Even cooking an aromatic meal right before a tasting can alter the aroma of wine up to an hour later. In addition, collectors should avoid eating anything spicy, strong in aromatic flavors (like garlic or onions) or that contains mint, as these foods can destroy a palate. Researchers in the study found that when bacteria was removed from the mouth, such as happens when tasters brush their teeth, the full aromatics of the wine do not come through. Not only does minty toothpaste alter a wine’s taste, but the removal of oral bacteria prevents the wine from releasing some of its essential aromatic compounds.

Jancis Robinson has similar tips for protecting a wine palate, adding that the age in which we are most attuned to our senses is between 30 and 60 years old. This means that collectors who are under 30 or over 60 might find it beneficial to get a second opinion on a wine to make sure that their natural palates aren’t fooling them. Because taste is so personal, and because it is so sensitive to change, it’s always a good idea to hold tastings with more than one person to receive additional opinions. This tip applies to those who want to buy or sell wines that they think others will enjoy, rather than those who simply want to drink the wines that they personally think taste the best.

For Rhône wine in particular, having a second opinion is important because many of these red blends have a gamey, animal-like aroma that comes from Brett. This bouquet can overpower palates that are not used to tasting this style of wine, and has led some critics to label Brett as a fatal wine flaw. Generally, the stronger a wine’s natural bouquet, the greater care a collector should take with a wine tasting because strong scents and flavors can overpower more subtle components that are present. The bacteria in your mouth might even exacerbate the already-strong bouquet once additional gas molecules are released on the first taste. To invest in wine that you want others to enjoy, Jancis Robinson says it helps to imagine the wine’s taste and aromas if they were made either stronger or more dull. For example, when she had to select wines for British Airways, Robinson said she had to alter the way she rated each wine she tasted, imagining what the wine would taste like if all of her senses were dulled. This is because the altitude of the airplane and the dry, pressurized air would make subtle wines virtually tasteless, even if they were delicious on the ground.

The best way to keep your natural palate from working against you is to list out the ways in which your palate might be biased. When selecting wines for other people, recognize these biases and try to account for them in wines. For example, if you hate the barnyard taste of Brett, but want to buy Rhône bottles for investment purposes, it helps to admit your bias against gamey tastes first. Knowing this, you can either go with your personal preference, or look beyond this component to find other qualities you like in the wine.

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