Taste Buds: Small structures concentrated on the tongue, but also found regions within the mouth and throat. Each is specialized to detecting a different taste (sour, salty, sweet, bitter, umami). Saliva helps dissolve food so that it may enter into the pores. (Pictured right) Fungiform papillae contain receptors for sweet and sour tastes. The structures buds with long protrusions are known as filiform papillae. They do not contain taste receptors, but are responsible for the abrasive coating of the tongue, exemplified in cats.
Miracle Fruit: Sour receptors are activated when they detect the presence of H+ ions. However, after consuming miraculin, an extract from the berries of the plant Synespalum Dulcificum, sweet receptors temporarily (~1 hour) respond to sour flavors. This provides a fun opportunity to experiment with different foods. While the berries work well, their short shelf life limits their usefulness. For purposes of classroom demonstrations, the tablets are cost effective and easy to use.
(Note: The tablets typically contain the berry concentrate in corn starch (ask students about allergies to corn products before using).
Allow 1/2 to 1 whole tablet to slowly dissolve on each person's tongue, coating it. Avoid hot foods and drinking fluids as these will shorten the duration of the effect.
Citrus Fruits: Slices of orange, lemon, grapefruit, and lime
Other Fruits: Sample other fruits like cranberries, kiwi, pineapple, apple, blackberries, etc.
Vinegar (try balsamic or salt and vinegar chips), mustard, ketchup, hot sauce, BBQ sauce, sour cream.
Alcoholic Beverages: non-flavored vodka or tequila. Stout beers.
For a bit less tasty, but none-the-less interesting experience make tea using Gymnema sylvestre. This will temporarily block sweet taste.
Steep 1/4 cup of cut leaf in one quart of boiling water for 10 minutes. This may be done an hour or two before the class. If you do not have a tea pot, use a coffee filter to strain the leaves from the tea.
The tea may be served hot or cold and will temporarily block sweet taste for 30-60 minutes.
Try: Sugar, salt, aspartame, sucralose, chocolate, and sweet-sour candy.