Taste•o•lo•gy (n.): the science of taste

story by Karuna Meda
photos by Alice Gao, Rachel Stone, Dana Robinson, Ed Zawadzki, and David Knipp

The tongue is a multi-tasking organ, with­out which we would not have the gift of gab or the palate. For most of us, the tongue’s abil­ity to taste has been simplified to five distinct populations of taste buds: sweet, sour, bitter, salty, and the most recently discovered umami: “savory” or “meaty.” This taste system evolved so that we could differentiate between high- nutrient sources and potential toxins. Not only is the science behind tasting extremely com­plex, but it can also explain why our taste buds pucker in anticipation of some foods, while they remain apathetic about the prospect of tasting others.

You sense taste when your brain detects changes in ion concentrations in receptors on your tongue. For instance, when you’ve (acci­dentally and unfortunately) poured salt into your coffee instead of sugar, there is a sud­den increase in sodium ions flowing through channels in your taste cells; after all, salt is simply sodium chloride. This change in ion concentration is detected as a deviation from the normal balance of ions, causing an elec­tric signal to travel to the brain via gustatory neurons. Similarly, sour foods cause a change in hydrogen concentration, while umami is derived from changes in extracellular cal­cium and sodium. On the other hand, large molecules like sucrose and alkaloids bind to specific receptors and activate biochemical pathways inside taste cells to create sweet and bitter tastes, respectively.

So how do we perceive a combination of tastes, like a sweetish-sour green apple? It turns out our taste buds act as a population sending signals to our brain, so the ones with the strongest signals dominate what we finally end up tasting.

Pseudo-tastes like “spicy,” “metallic,” and “dry” are actually detected by pain or tac­tile receptors on our tongue. So after you’ve assaulted your tongue with Sriracha hot sauce, frantically gulping down cold water won’t actually wash away the “taste.” It will, however, soothe the taste buds that have been pinched by capsaicin, which causes the spici­ness in hot peppers.

Our sense of smell accounts for nearly 75% of what we taste. When you put food in your mouth, odor molecules travel through the nasal passage to olfactory receptors in your nasal cavity. If mucus builds up in the passage, odor molecules cannot reach your olfactory receptors. That’s why even the most aromatic foods are tasteless when we’re stuffed up.

Our sense of smell can explain our innate attraction to some flavors and aversions to oth­ers. Volatile oils pleasantly tickle our noses, causing favorable “tastes” like “piny,” “floral,” and “minty.” These volatile oils are released by herbs, flowers, and spices found universally; this is the basis for our love of certain flavors like strawberry, vanilla, and even chocolate. The fermentation of chemicals such as caf­feine and theophylline found in cacao beans makes the smell of chocolate very appealing.

In fact, our keen sense of smell for these vol­atile oils has medical advantages too. Common spices, herbs, chili, and garlic contain potent antimicrobial and antifungal chemicals. It makes sense, then, that these ingredients are often used in poverty-ridden countries, where foodborne diseases are rampant.