Sense-ational Science
understand the science behind taste by studying gustation, olfaction, and what happens when these senses are altered
We are taste of science; we bring mind-bending science out of the lab and into bars near you! When was the last time you thought about the biology of taste? Was it sixth grade, looking at an outdated diagram of sweet and salty taste bud regions on the tongue? If that’s the case, join us for a refresher course on gustation — we promise this will be a whole lot more fun! We’ll scramble your senses so you can test whether your nose or tongue contribute more towards your enjoyment of beer (or wine!), and we’ll put that old diagram to the test and find out where sweet and salty taste buds are really located on the tongue. Bon ap!
Supplies needed:
- Jelly beans
- Gymnema tea leaves
- Containers for tea
- Snickers bars
- Paper cups
- Sugar, artificial sweetener packets
- Salt packets
- Print out of powerpoint presentation
Prior to event
Read “Use of the Herb Gymnema sylvestre to Illustrate the Principles of Gustatory Sensation: An Undergraduate Neuroscience Laboratory Exercise” for background.
Review slides and basic scientific information on gustation and olfaction:
Morning of event
Put about 5 heaping tablespoon in 1 quart of boiling water and let it steep for about 5-10 min. Filter with coffee filter (wet coffee filter first)
Activity
Introduction: Begin by asking participant what they know about taste. What senses are involved? Ask about memories with taste. Do they remember the tongue map from 6th grade?
1. Hand out 1 jelly bean
Guess the flavor of the jelly bean based on color. Plug nose and start chewing jelly bean. Unplug nose after a few chews and try to guess flavor
Goal: Highlight how smell and sight affect our ability to taste. Participant will likely not be able to distinguish the flavor when their nose is plugged, but will have a rush of flavor when they unplug their nose
2. Warning: taste will be affected for 20 minutes.
Tea not suitable for individuals with diabetes (alters blood sugar levels). Give small amount of tea in paper cup. Swish tea around in mouth for ~10 seconds (try to coat all of mouth). Have them try the following items:
- Snickers bar
- Sugar vs aspartame
- Jelly bean (with and without plugged nose)
- Salt
- Beverage (beer, cocktail, wine)
Goal: Participant will no longer be able to taste sugar, and the items above will all have altered tastes. Highlight how taste buds affect our ability to taste. Have them guess which taste receptor is blocked by the tea (answer is sugar receptor). Highlight how the aromas in jelly beans give the fruity flavor, not the sugar
3. Discussion points
Taste buds consist of neurons that respond to salt, bitter, sweet, sour, or umami. The “tongue map” with distinct taste regions is incorrect, as each taste bud consists of neurons that respond to all five tastes (although there are areas where tastes are heightened).
Olfactory neurons branch down into the nasal cavity and synapse in the olfactory bulb. These neurons respond to airborne chemicals, or odors
Taste and smell neurons have chemoreceptors that respond to a particular chemical (similar to lock and key). Once a molecule binds to the neuron a signal will be sent to the brain. The brain differentiates what type of taste or odor neuron sent the signal
The sensation of flavor is a combination of gustation and olfaction. Smell is directly linked to taste through orthonasal olfaction (through the nose) and retronasal olfaction (behind the nose through the retronasal passage). Whenever we eat food the brain receives signals through the taste buds and olfactory neurons, and both are incorporated into the overall flavor of the food. This is demonstrated by diminished flavor sensing when our noses are stuffy.