Olfaction Pre-class

1. A taste map of the tongue has appeared in countless books:

	http://www.understandingfoodadditives.org/pages/Ch2p3-1.htm

In your experience, is this map correct? Taste a few things if you need to.

No, this does not seem correct, although the front of my tongue seems more sensitive.

2. During your next meal, after eating a few items, try them again with your nose plugged. Record your observations.

With my nose plugged the flavors were much less enjoyable. With my apple juice, for example, I could still detect sweetness, but that full-bodied apple ‘flavor’ was missing. Again with my cereal, sweetness was still obvious with my nose plugged. The flavor was again less enjoyable, and I found myself more focused on the actual texture of the flakes.

3. Read “More than meets the mouth” by Michael Eisenstein (posted on Moodle).

· What are the 5 tastes (according to current thought) and 2 tastes for which the jury is still out?

o Sweet, sour, bitter, salty, and umami are the five main tastes, with fatty acids, calcium, and carbonation all potentially tastes as well.

· Eisenstein suggests that “the wisdom of the body” leads people to prefer foods that contain the most nutrients. Consider things with a pleasant taste vs. those with a bitter taste--how might this wisdom also lead us eat things with calories and avoid those with poisons?

o Poisonous foods are generally associated with a bitter taste, thus, we seek out sweet foods. Furthermore, our bodies innately prefer sweet foods – this is a handy ability when fruits are the sweetest food around, but is unhealthy given the modern food industry.

· Broccoli is well known to be rich in bitter compounds. Use what you learned in this paper to explain why people could have such opposing reactions to broccoli, as demonstrated by this quote from President George H. W. Bush: “I do not like broccoli and I haven’t liked it since I was a little kid and my mother made me eat it. And I’m President of the United States and I’m not going to eat any more broccoli…My family is divided. For the broccoli vote out there: Barbara loves broccoli. She has tried to make me eat it. She eats it all the time herself.”

So far, 25 bitter taste receptors have been identified, and the sensors all detect different bitter compounds. Genetic factors have been linked to malfunctioning bitter receptors, and geographic and ethnic factors have been shown to change the distribution of bitter receptors. These differences explain why people can have opposing reactions to the same food – one may not taste the bitter compound, and therefore enjoy the food, while the bitter-taster may not like the food at all.

4. Consider vision, gustation, and olfaction. Which two systems are the most alike? Why?

Vision and olfaction are most similar. In these systems, different receptors work together to create a particular color or scent. A unique combination of ligands binding to the receptors causes a unique response. With taste, there are only several possible catagories that a flavor can fall under.

5. Describe an analogy that you could use to explain olfaction to someone outside of this class.

Olfaction is like a protein. In a protein, many different atoms combine in a very particular way to assemble into one unique protein. With olfaction, many molecules, in combination with one another, bind to a particular set of receptors, generating a unique smell.