Are you familiar with the cliché: beauty is in the eye of the beholder? When it comes to wine, beauty may lie in the aromatic and flavor perceptions of each wine lover. Much has been written about wine tasting, with a focus on the grapes, the appellation, the vintage, the winemaker, and the tasting technique itself. Given the many factors that go into crafting the finest wines, it’s easy to believe that you, as a wine consumer, are a mere passive observer of the flavors and aromas developed in wine as it ages. Think again.
Fruit-forward. Notes of dark cherry, red currant, and raspberry, plus hints of vanilla and baking spice.
Is this a description of your favorite Pinot Noir, or a holiday fruitcake? Have you ever wondered why your favorite wine reminds you of other scents derived from food morsels seldom found in your glass? Neuroscientific studies have shown that flavor is an active sense, in which your brain plays an integral role in creating the sight, smell, and taste you experience (Small, 2006). The intricacies of the combined biomechanic and brain mechanisms responsible for the taste of wine are only just being elucidated in the interdisciplinary field of neuroenology (“neuro” meaning brain, “enology” meaning the study of wine) (Shepherd, 2015).
As you watch the wine being poured into your stemmed glass, neurons, the cells that communicate messages within your brain, project to your visual cortex to create an image of the scene. Your recognition of this liquid activates brain regions responsible for memory, ushering your mental schema of wine to conscious thought. Perhaps you’re examining the hue or turbidity of the wine, forming notions of the flavor to come. A growing body of literature highlights that specific colors are associated with particular tastes, priming the palette before the wine reaches your tongue (Spence, 2015). As one neuroscientist puts it, “we eat first with our eyes” (Scalfani, 2013). Already, the tasting experience has begun.
To understand how the brain creates the taste of wine, one must appreciate both the gustatory system, responsible for taste, and the olfactory system, responsible for smell. The gustatory system is composed of taste cells in the mouth that respond to chemical compounds in the food and beverages you consume, and signal to the gustatory complex in the brain to create your perception of flavor. These taste cells are responsible for sensing all five taste modalities: salty, sweet, bitter, sour, and umami. Recent findings suggest that movement of the tongue while manipulating food in the mouth is more complex than the movements used in creating speech (Lieberman, 2011). Many are quick to credit the taste cells as the sole proprietors of flavor, without considering the role of olfaction.
Smell is a dual sense; odor stimuli can be delivered by breathing in (i.e., orthonasal olfaction) and breathing out (i.e., retronasal olfaction). Olfaction begins when odorant molecules enter the nasal cavity via inhalation through the nose or rising through the mouth from food or beverage. These molecules bind to receptors that signal to the olfactory bulb, which activates a broader cascade of neural signals responsible for smell recognition, memory, and emotion. The neural activity that represents the response of the brain to a particular odor constitutes an odor map or odor image (Shepherd, 2006). While odor patterns are highly complex and are registered unconsciously, their recognition is crucial for smell perception.
Following a brief swirl of the glass to release aromas from the wine, you lift the glass to your nose and take a deep breath in. The aromatic molecules wafting out of the wine glass enter your nose and interact with receptors in the nasal cavity that project to the olfactory bulb. When you sniff from a glass of Pinot Noir, the aromatic compounds released from the wine activate your olfactory system in a similar manner to flavor and scents you have previously and subconsciously categorized as derivatives of other everyday scents.
You lift the glass to your mouth and take a sip. The taste and touch receptors on your tongue are flooded with further sensory input as the motor systems that control the muscle movement of your tongue, cheek, and jaw activate and you develop a mouth-feel for the wine. As gustatory and olfactory cues add to your visual analysis, these sensory images condense into a central, neural representation of a wine flavor object.
As stimuli in the language of the senses are translated into the language of the brain, your sensory systems condense your sensory experience and archive the information for future reference.
Many experienced tasters will pull air through their lips while the wine is suspended in their mouth to aerate the wine. Similar to the swirling of the wine, this process further releases aromatic molecules from the wine, which are sensed by the brain as you breathe out. X-ray observation of the head and neck during liquid consumption demonstrates that the passage between the nose and mouth (i.e., nasopharynx) is open when the liquid is in the mouth, but closes when swallowing (Shepherd, 2015). Thus, with wine in your mouth, breathing in and out occurs as you sense the taste of the wine, but the flavor is muted when swallowing.
Evidently, the complex flavor of wine comes from much more than taste on your tongue. As stimuli in the language of the senses are translated into the language of the brain, your sensory systems condense your sensory experience and archive the information for future reference. Thus, it is ultimately the messages and memories about smell and taste, old and new, that converge during the tasting experience that allow us to detect flavors in food or wine.
Sclafani, A. 2013. Gut–brain nutrient signaling. Appetition vs. satiation. Appetite 71:454-458.
Shepherd, G.M. 2006. Smell images and the flavour system in the human brain. Nature 444.
Shepherd, G.M. 2015. Neuroenology: how the brain creates the taste of wine. Flavour 4:19.
Small, D.M. 2012. Flavor is in the brain. Physiol Behav 107:540-52.
Spence, C., X. Wan, A. Woods, C. Velasco, J. Deng, J. Youssef, and O. Deroy. 2015. On tasty colours and colourful tastes? Assessing, explaining, and utilizing crossmodal correspondences between colours and basic tastes. Flavour 4:23.