Taste, at the most basic level, is the activation of receptors located on your tongue. However, these receptors, commonly known as taste buds, are also found on the soft palate, upper esophagus, cheek, and epiglottis. Most are aware from childhood that humans are sensitive to different elements of taste perception. For those a bit older, they might recall four of these elements: salty, sour, bitter, and sweet in relation to a (false) map of the tongue. In actuality, there is no regional specialization in taste perception of the tongue. The fifth, and final, taste element is referred to by the Japanese word, umami. While discovered over a century ago by Kikunae Ikeda, this “savory” flavor was not fully recognized until 2000 with the discovery of a specific taste receptor.
The discussion of taste in class provides numerous opportunities for interactive and informative demonstrations. Very few of the materials used in the described demonstrations contain common allergens. Still take care to clearly label and inform students of the items used.
Just as vision and hearing differs among individuals, certain people experience taste with much greater intensity than others. This genetic variation in taste experience was identified by Dr. Linda Bartoshuk. If you are wish to control for individual differences you can perform a "Magnitude Estimation" test using auditory tones to assess the general responsiveness of a subject.
2) Do you drink coffee? If so do you add cream and sugar?
3) Do you frequently add salt to food?
4) Do you like spicy food?
5 ) Do you enjoy green vegetables like broccoli, brussel sprouts, and kale?
6) If you drink alcoholic spirits, do you find the taste to be burning, slightly sweet, or in between.
7) Are you a picky eater?
8) Do you like cilantro on foods (typically use in Mexican and many Asian meals)?
Blue Dye: By applying food coloring to the tongue you can count the number of taste buds in a given area. There is some disagreement as to whether supertasters have a greater density of buds.
1) Dry your tongue with paper towels.
2) Use cotton swabs to apply blue dye to the tongue.
3) Keep the tongue extended to allow the dye to dry.
4) Place a cut-out with a set size (e.g. 100mm2) over each tongue and take a picture.
5) Count the number of taste buds. Wait to compare until after additional tests.
Propylthiouracil (PROP): Supertasters will find this substance incredibly bitter. Keep track of the intensity of each person's response.
While PROP is not a flavor you are likely to encounter outside of a classroom or laboratory setting, sodium benzoate (food preservative) and thiourea compounds (broccoli, brussel sprouts, and kale) are found in a variety of foods. If an individual can taste PROP, then they can taste these chemicals.
Compile all your findings. Do you see any patterns emerge as to food preference and taste sensitivity.