Taste Is More Than Just Flavor
The words “flavor” and “taste” are often used interchangeably, and incorrectly. Flavor is how our brain processes the chemical compositions of food and categorizes them, such as sweet or bitter. Taste, however, is a more complex phenomenon; it includes flavor, texture, temperature, and smell of the food we consume. In determining taste (or the lack of it), simply focusing on flavor ignores the sensory nuances that determine whether a certain food item is tasty.
When all the factors that comprise taste are considered, the possibilities of how we, as humans, can create and enjoy different foods increase exponentially. Scientists say the human brain is capable of sorting and registering hundreds of thousands of tastes. But, first, we have to sort through the misinformation peddled to us in textbooks that makes realizing this process, and therefore capitalizing on the possibilities, difficult.
Textbooks will tell you the human tongue has zones where only a certain type of taste bud is located, which can register only a certain type of flavor: Sweet at the tip of the tongue, bitter at the back, and sour at the sides. This tongue map has largely been unquestioned; even though it’s false. While the scientific community is still making slow progress when it comes to figuring out how the human brain perceives flavors, we now know one thing for sure: the science of taste is way more complex.
The entire human tongue can detect the complete gamut of flavors — salty, sweet, bitter and sour. Scientists have been playing around with a fifth fundamental flavor, however, called umami; it’s a “meaty” or “savory” flavor (for example, how broth tastes) elicited from glutamate, an amino acid present in meat and fish.
These flavors are detected by taste buds present within the several kinds of papillae — rounded protuberances on the tongue’s surface that give it texture. Within the taste buds are taste receptor cells, 50 to 100 in humans, which contain essential proteins that make sense of the chemical composition, and resulting flavor, of the food being chewed. These chemicals, initially absorbed into saliva, change the electrical composition of the taste receptor cells by interacting with the proteins; for example, salty foods will change taste receptor cell composition by inserting sodium (Na+) ions into it; or acidic/sour foods insert hydrogen ions (H+) into the taste cell; scientists have found chemicals from umami-flavored foods bind to proteins in taste receptor cells in rats. This binding activates the receptor cell, prompting it to release “chemical signals called neurotransmitters, which prompt neurons connected to the taste cells to relay electrical messages” to the brain, according to the Scientific American.
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Scientists have found that the tongue map peddled to us as children is actually a brain map — neurons in the brain are hard-wired to detect certain flavors. It’s not as if individual neurons can detect only one flavor; brain neurons have stronger affinities to detect certain flavors, and lower for others — a phenomenon scientists are attempting to map in its entirety. But these neurons can still identify the gamut of flavors being transmitted to the brain, just like the tongue.
The neurons present in the taste pathway also transmit signals stemming from other senses, for example, the sense of smell — this is apparent in how it’s hard to taste things during a severe cold. These neurons also record whether the taste is pleasant or unpleasant, and the texture and temperature of the food, according to the Scientific American. For example, food is often described as hot or spicy, but these are not flavors — the chili present in foods causes the tongue’s receptor cells to feel pain and heat, which is then felt by the neurons that deliver a pain signal to the brain.
These nuances of taste have helped us evolve as humans. “Taste is responsible for evaluating the nutritious content of food, guiding essential appetitive behaviors, preventing the ingestion of toxic substances, and helping to ensure the maintenance of a healthy diet,” according to a report published in Nature. “Sweet and bitter are two of the most salient sensory percepts for humans and other animals; sweet taste allows the identification of energy-rich nutrients whereas bitter warns against the intake of potentially noxious chemicals.”
Taking into account the various factors that underlie taste, it’s important to understand the intricacies of the tasting mechanism, so we can then start manipulating it to our preferences. And then? We feast.