A Matter of Taste
Dr. Nirupa Chaudhari has been honored with the 2025 Max Mozell Award for Outstanding Achievement in the Chemical Senses.
Tasting can both thrill and annoy, but how does it work?
For 30-plus years, Nirupa Chaudhari, Ph.D., has been looking for answers. Her efforts have earned her the coveted Max Mozell Award for Outstanding Achievement in the Chemical Senses from the Association for Chemoreception Sciences. The award honors scientists for their determined efforts to understand chemical receptors.
“This award is a welcome surprise and a tremendous honor,” said Dr. Chaudhari, professor of physiology and biophysics at the University of Miami Miller School of Medicine. “For me, chemoreception has been a fascinating field because it’s both the focus of my work and a significant part of my day-to-day experience.”
Figuring Out Taste
Taste is not one thing but many. Consider a spoonful of butter pecan ice cream. The mouth is dotted with chemical and mechanical receptors. Taste buds are only one variety. There are receptors for sweetness, saltiness and all the other components of taste, as well as the sensation of cold, the ice cream’s smooth feel and the pecans’ crunchy texture. All these receptors pass this information to neurons, which send messages to different parts of the brain.
“We have this phenomenon neuroscientists call convergence,” said Dr. Chaudhari. “I don’t know if there is a brain center for ice cream. But if there is, it receives signals from all these receptors, as well as aroma, to produce flavor. And the brain says, ‘OK, we have butter pecan.’”
But in the 1990s, almost none of this was known. Dr. Chaudhari was trained as a molecular biologist studying gene expression. But the more she learned about chemoreception, the more interested she became. Nobody seemed to know how the molecular sensors in the mouth produced taste.
“There were specific questions that were left completely unaddressed,” she said. “How do receptors bind to a sugar molecule? How do these interactions get converted into electrical signals that go to the brain?”
Dr. Chaudhari was a junior faculty member at Colorado State University when she and colleagues identified the receptors for an entirely new taste—umami. Sometimes called the fifth taste—the first four are sweet, sour, salty and bitter—umami describes savory, meaty flavors like parmesan cheese or sautéed mushrooms. Over time, the science crept into the popular culture.
“Right about the turn of the 21st century, a lot of these molecular analyses came to the forefront,” said Dr. Chaudhari. “Scientists figured out what the receptors were and how they bind to the different taste molecules to sense umami. That was a novel discovery that sort of percolated into the world.”
The Brain and Taste
Having spent decades studying how taste and other receptors operate, Dr. Chaudhari is investigating how nerves transmit that information to the brain. Are they unbiased agents or do they modify information in route?
“How precisely is that information coded and does the hardware, the nerve carrying the signal, confer any information or not?” asks Dr. Chaudhari. “These are really important neurological questions and they are also related to clinical questions about how information is coded when people develop eating or metabolic disorders. If a specific part of the circuitry stops working, would appetite change or might sugar be avoided?”
The questions are virtually endless. How do people perceive flavor? Some Asian countries have few sweets in their diets. The sweet receptors in those populations are highly sensitive. This implies that taste preference, to some degree, is learned, and animal studies back that up. Most animals don’t have much sugar in their diet.
“The first time they encounter sweet, they’re a little afraid of it,” said Dr. Chaudhari. “It tastes funny to them and they really don’t like it. But then they get that nutritional reward. The glucose gets absorbed and it has a high caloric content and the brain says, ‘This is good stuff.’ Two or three days later, they’re gulping it down to the exclusion of water. It’s a learned preference based on metabolic reward.”
Tags: Department of Physiology & Biophysics, Dr. Nirupa Chaudhari, taste, taste buds