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Why Are Peppers Hot?

Can You Beat Jet Lag?

How Do Bees Fly?

Why Does Traffic Jam?

Sand to Nuts

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TEACHING GUIDES


Life's Little Questions:
Why Are Peppers Hot?


Chile peppers are notoriously hot. But does anyone know why? Food researchers explain it's the capsaicin in the peppers that makes them hot. Recently, scientists were surprised to discover that capsaicin is also the source of a medical breakthrough, seen here on TV for the first time. Paradoxically, what makes peppers burn can also bring relief from pain -- under the right circumstances.

Curriculum Links
National Science Education Standards
Genetics of Taste
Activity: Are You a Supertaster?
Capsaicin Pain Relief




CURRICULUM LINKS


BIOLOGY/
LIFE SCIENCE


evolution, nervous system, plants

CHEMISTRY


 

GENETICS


 

HEALTH


disease

SOCIAL
STUDIES


geography




NATIONAL SCIENCE EDUCATION STANDARDS

SCIENCE AS INQUIRY / LIFE SCIENCE
5-8: Structure and Function in Living Systems, Reproduction and Heredity, Diversity and Adaptations of Organisms
9-12: Biological Evolution, Interdependence of Organisms, Behavior of Organisms
SCIENCE IN PERSONAL AND SOCIAL PERSPECTIVES
5-8: Personal Health, Science and Technology in Society
9-12: Personal and Community Health, Science and Technology in Local, National and Global Challenges
HISTORY AND NATURE OF SCIENCE
5-8: Science as a Human Endeavor, Nature of Science
9-12: Science as a Human Endeavor, Nature of Scientific Knowledge




GENETICS OF TASTE

Does broccoli taste bitter? Is eating hot peppers intensely painful? Scientific evidence suggests a genetic basis for food preferences -- and it's all on the tip of the tongue. Infants are born with a genetically determined number of taste buds. Some have only a few hundred, while others have tens of thousands per square centimeter. The mushroom-shaped structures on the tip of your tongue are called fungiform papillae. Each contains about a half dozen taste buds. Other bumps on the tongue are different kinds of papillae that do not contain taste buds.

Linda Bartoshuk, seen on Frontiers, is professor of surgery and taste researcher at Yale University School of Medicine. She divides people into three groups: supertasters (25% of the population), medium tasters (50%) and nontasters (25%). According to her research, supertasters have many more taste buds per square centimeter, which enables them to experience the taste, temperature and texture of foods more keenly than nontasters.

Of all the senses, taste is the least understood. We do know that smell is closely associated with taste. In the 1930s, researchers accidentally discovered a chemical substance that was tasteless to about 25% of people and bitter to the other 75%. Today's genetic studies continue to provide more data about the complex sense of taste.


ACTIVITY: ARE YOU A SUPERTASTER?

Here's a simplified adaptation of Bartoshuk's taster test you could try using blue food coloring and a plastic reinforcement ring for a three-hole binder (paper reinforcement rings get mushy). Use a cotton swab to wipe some blue food coloring on the tip of your tongue. Place the ring on your tongue. If you are a medium taster, you'll see only a few little "mushrooms" inside the ring's opening. If you're a supertaster, you'll find more than 25 of them within the circle. How many do you count?

QUESTIONS

  1. What might be some evolutionary advantages to being a supertaster -- for animals and humans?

  2. What other factors might explain a person's food preferences?

  3. Supertasters find coffee and cruciferous vegetables (broccoli, cabbage) too bitter, and sugary foods sickeningly sweet. Supertasters can also detect gradations in fat; for example, they can taste the difference between skim and whole milk. Using these findings, design a taste-testing experiment to identify supertasters.

  4. Columbus and other explorers introduced peppers to the rest of the world, along with other New World foods like potatoes and tomatoes. Research different kinds of peppers used in cuisines throughout the U.S. and the world. What peppers are grown in your area or available at local markets?

  5. All peppers are rated on a heat scale (bell peppers are zero). Look up the ratings at: www.wiw.org/~corey/chile/scoville.html



CAPSAICIN PAIN RELIEF

hot pepper Taste researchers have recently discovered that capsaicin, the component that gives peppers their heat, can also be used as an anesthetic and pain reliever. The foot treatment demonstrated on Frontiers is in an experimental stage of testing and not available to the public. (Over-the-counter gels and ointments contain a weaker solution of the chemical.)

Hot pepper candy made with chiles and taffy relieves mouth sores of people undergoing chemotherapy. Researchers believe capsaicin reduces substance P, a neurotransmitter that carries pain messages to the brain. To learn more, visit oncolink.upenn.edu/cancer_news/1994/hot_candy.html.

Remember, when handling hot chiles, wear rubber gloves and do not touch your lips or eyes.





 

Scientific American Frontiers
Fall 1990 to Spring 2000
Sponsored by GTE Corporation,
now a part of Verizon Communications Inc.