The Somm Journal

Dec 2015-Jan 2016

Issue link:

Contents of this Issue


Page 105 of 124

{ }  105 How We Taste To begin even a cursory study of wine quality, it's essential that we understand our own physiology and the types of sensory information that we're processing. We also need an analytical method for recording our observations and perceptions. With as much as 80% of our perception of flavor attributed to aroma or smell, the olfactory system is doing most of the heavy lifting when we're evaluating wine. Professional tasters including winemakers and trained wine judges can reliably evaluate dozens of wines and, in some cases, may taste in excess of 150 wines that are in various stages of fermentation or development on any given day. Evaluating that number of wines takes practice and the skill could be considered the Olympic weight-lifting of wine tasting. It's entirely possible because we can quickly refresh our sense of smell—raising your heart rate is one way—and because olfactory receptor cells have the ability to regenerate. There aren't many specialized cells in the human anatomy that can regenerate, and that includes our taste receptors. The number of taste buds we're born with varies by individual and, on average, we lose half of our taste receptors by the time we're 20 years old. When we're smelling and tast- ing wine, we're using our chemosensory senses, and both the olfactory and gustatory sensory systems work in tandem. Aroma and flavor molecules undergo an exchange known as transduction, by which they become electromagnetic signals that travel to the olfactory and gustatory cor texes for processing by higher areas of the brain. But aroma and taste aren't the only components of flavor. There's temperature and texture to account for as well. Both are sensed by the trigeminal nerve, which also enervates the taste buds and sends signals to be processed in the somatosensory cortex. All three sensory systems—the olfactory, gustatory and trigemi- nal—operate within the limbic system and process sensory information to complete the perception of flavor. Mastering Aroma Molecules However resilient, your sense of smell can still fatigue; you experi- ence this when your olfactory receptor cells are filled up with aroma molecules. Of the several hundred volatile aroma com- pounds found in wine, cork taint caused by 2,4, 6-trichloroanisole (TCA) is a particularly fatiguing as it distorts the perception of smell. The molecule partially blocks olfactory signal transduction allowing only a few aroma molecules to pass through the cell wall as electrochemical signals. That's why the fruit and positive aromas of corked wines are suppressed. We're not smelling the TCA; it's blocking us from smell- ing the wine's dominant aromas. What we do smell are the truly unpleasant aromas that are found in all wines but are normally masked by aroma molecules that are easier to detect. Whether it's perceived as a flaw or fault, TCA has one of the lowest detection thresholds of all the off-putting molecules that taint wine.* Our ability to detect odors is one of our superhuman pow- ers. Odors are created by a family of molecules, some of which are more dominant and, as such, are easier to detect. Vanilla, for example, is a common aroma and flavor in wine that's composed of 170 different volatile aroma compounds with vanillin being the most dominant. Vanilla is one of the few low threshold aromas that can be enjoyed at a very high concentration without losing its appeal. These unique characteristics are what make it such a popular aroma and flavor. Until recently scientists thought that humans could only detect about 10,000 odors but new research has demonstrated that the number is far greater. The average person can detect upwards of one trillion odors but even the most highly-trained sensory expert can only identify a few thousand. Detecting off odors is just the beginning. To reliably identify flaws and faults in wine, we're sifting through a family of volatile molecules dominated by one that smells the strongest. A taster has to be able to recognize and identify the dominant molecules responsible for the defect. The recognition threshold is the lowest concentration of an odor that can be identified by a taster. When 50% of tasters can identify an odor, it's said to be at the perception threshold. Most of the compounds with low odor thresholds that are found in wine including pyrazines, thiols and various mercaptans are pungent and negative at high concentrations. They're among the many culprits that detract from wine quality. Said one wine writer when confronted with an unrecognizable fault, "The big- gest problem with wine faults is that there are so many." One of the easiest way to get up to speed in identifying garden- variety and less common wine faults is to spend a day judging a home winemaking competition. All you need is a basic understand- ing of what can go wrong in the vineyard, tank, barrel or bottle to result in a wine that's out of condition and to recommend the most likely remedies. Typically your tasting notes will be anonymously returned to the winemakers and you'll be indirectly improving wine quality while you master the offending molecules. *Much of this research is summarized in Wine Faults: Causes, Effects, Cures, by John Hudelson, Ph.D. (Board and Bench Publishing, 2010). ILLUSTRATION ILBUSCA VIA ISTOCK

Articles in this issue

Links on this page

Archives of this issue

view archives of The Somm Journal - Dec 2015-Jan 2016