Sensory Science: Testing Taste Thresholds
During the holidays, we often find ourselves surrounded by a wide variety of taste sensations. Have you ever wondered how well we sense different tastes? People are generally able to discern five basic tastes: sweet, umami (also known as savory), salty, sour and bitter. Is it easier to detect some of these flavors at low concentrations compared to others? In this science activity, you (and possibly your friends and/or family) will find out by exploring your taste thresholds for sweetness, saltiness and sourness. Get ready to find out how low you can go!
This activity is not appropriate for use as a science fair project. Good science fair projects have a stronger focus on controlling variables, taking accurate measurements, and analyzing data. To find a science fair project that is just right for you, browse our library of over 1,200 Science Fair Project Ideas or use the Topic Selection Wizard to get a personalized project recommendation.
Our sensory system for taste is remarkably sensitive. Not only can we detect substances at extremely low concentrations, we can also differentiate between molecular compounds that are closely related. For example, for some molecules we can distinguish between different stereoisomers, which are molecules that are made of exactly the same components, but are mirror images of one another. The artificial sweetener aspartame is an example of this – it tastes sweet to us, but its stereoisomer does not.
This amazing sensitivity is made possible by our taste buds. Taste buds, located on small bumps on the tongue called fungiform papillae, are each made up of about 50 to 150 taste receptor cells. On the surface of these cells are receptors that bind to small molecules related to flavor. Through sensory nerves, the receptors relay the taste sensation information to the brain. This entire process allows us to discern five basic tastes.
Extra: Try repeating this activity using several volunteers. Compare your results. Do some people generally have lower thresholds than other people? Is there variation in which taste has the lowest threshold for people in the group?
Extra: Recruit several volunteers in different age groups to take this threshold of taste test. Does taste threshold change predictably with age?
Extra: In this activity you used 10-fold serial dilutions to roughly establish your threshold of taste. Design a test to determine your threshold with higher precision. What exactly is your taste threshold for sugar, salt and vinegar?
Observations and Results
Could you taste all of the 10% solutions, but none of the 0.01% solutions? Did the sugar solutions have the highest threshold, meaning you could only taste it in the more concentrated solutions, compared to the salt and vinegar solutions, which had lower thresholds?
For the sugar, salt and vinegar solutions, the 10% solutions should be detectable by nearly everyone who tries the test, while almost no one should be able to detect the 0.01% solutions because the concentrations are too low. The different basic tastes (sweet, salty and sour) have different thresholds, or concentration levels, at which they can be detected. In other words, it’s easier to detect some flavors at low concentrations compared to others flavors. Taste thresholds can vary from person to person. You may have seen that the sugar solutions were harder to taste at lower concentrations compared to the salt and vinegar solutions. In other words, the sugar solutions may have had a relatively high taste threshold compared to the salt and vinegar solutions. You may have also seen that the vinegar solutions had a lower threshold compared to the salt solutions (meaning the vinegar was easier to taste at lower concentrations), but this difference can be minor and may require testing many individuals to see a clear trend.
More to Explore
Teisha Rowland, PhD, Science Buddies
Science Buddies |
Taste, perception, senses, food, the brain
Explore Our Science Videos
Slow Motion Craters - STEM Activity
DIY Toy Sailboat
Why Won't it Mix? Discover the Brazil Nut Effect