Taste and Aroma

Activity 1: How does taste work?

Questions:

1. What different tastes can you determine? Is the tongue map from your handout correct? Map each taste as best you can on your tongue.
a. I found the taste map provided to be quite accurate to what I actually tasted. Since I cannot draw out the diagram of the tongue and the location of taste for each food item, I will simply describe where each taste was located on my tongue.

2. Orange Juice:

a. When my nose was plugged I did not really detect any taste. It tasted slightly acidic, but no significant taste was detected. However, without my nose plugged, I could definitely taste the orange juice. It tasted significantly bitter on the back of my tongue, near my throat. Also, it was very sour on the sides of my tongue near the back. There was a tinge of sweetness on the very tip of my tongue.

3. Soy Sauce:
a. When my nose was plugged I could not taste much of anything on my tongue. It was a little salty, but I could not really specify a taste. However, when I unplugged my nose the soy sauce tasted slightly bitter on the very back portion of my tongue. There was also a significant salty taste on the sides of my tongue, near the front portion of my mouth.

4. Lemon:
a. When my nose was plugged I was able to taste an extremely bitter taste which covered the entire back area of my tongue. The taste was almost worse than expected and very bitter. When I unplugged my nose it was bitter on that same portion of my tongue, but not as bad as when my nose was plugged. I was also able to taste a significantly sour taste on the sides of my tongue, near the bitter area.

5. Coffee:
a. This was the final item I tasted at this station. When my nose was plugged, there was a very large, bitter taste. This bitter taste covered the entire back portion of my tongue and even seemed to travel to the sides a bit. However, when my nose was plugged there was no flavor apparent. However, when I unplugged my nose, there was still that same bitter taste but there was the slight flavor of the coffee. The bitter portion continued to cover the back section of my tongue.

6. How many different types of bitter have I tasted? Do you think they all bind to identical taste receptors?

a. I felt that I tasted a different kind of bitter for each item. With the orange juice it was a more acidic bitter taste. The soy sauce seemed to have more of a salty kick to the bitter. The lemon was also more acidic in its taste. The coffee seemed to have a different bitter taste entirely that was unlike any of the others. From this I can conclude that they do not all bind to identical taste receptors. Although they may bind to some of the same receptors, they do not all bind to identical receptors because of the quite noticeable difference in bitter taste.

After brushing my teeth: What tasted the same, what tasted different?

1. Orange Juice:
a. After brushing my teeth, the orange juice tasted sourer than before. The sour taste was still on the back, side-portions of the tongue but slightly more intense than before. I could not really taste the bitter or sweet tastes this time.

2. Soy Sauce:
a. I could really only taste the salty tastes this time. This was also in the same location, however the salty taste seemed more “tame” than before. I could not taste the bitter flavor at all this time around.

3. Lemon:
a. Tasting this a second time was far more intense than previously. The bitter taste at the back of the tongue was a lot more significant. The sour taste was also in the same location on my tongue but was significantly intensified. The bitter and sour tastes almost took my breath away and was quite unpleasant.

4. Coffee
a. The coffee taste was significantly more bitter than before. The bitter taste was still located on the back portion of my tongue, but the taste was intensified. The taste was extremely unpleasant after brushing my teeth.

Figure 4 question:

1. Which type(s) of receptors do you predict would be most affected by your toothpaste? Is this what you experienced?
a. I predicted that the sweet taste would be most affected by my toothpaste. This proved to be my experience. I could still taste the bitter and sour tastes of the food after brushing my teeth. However, after brushing I was unable to taste any of the sweet tastes and the sweet taste did not seem to linger on my tongue after brushing, as the sour and bitter tastes did.

Activity 2: What else is involved in taste?

The taste tester in our group was able to identify all of the items when her nose was unplugged. However, when her nose was plugged she was able to feel the texture and a bit of the sweetness, but could not differentiate between the various foods.

Questions:

1. What happened to your taste perception when you plugged your nose? What does this tell you about taste?
a. When I plugged my nose the taste sensation went away almost completely. The taste that made each food unique went away and made it nearly impossible to tell which food was being tasted. This tells me that smell and taste are very closely connected. If something is wrong in the nose it is going to directly influence taste. This explains why when I have a stuffed nose during a cold; I have difficulty tasting my food.

2. Did the blindfold affect your ability to “accurately” taste the food? What can you determine from this?

a. The blindfold did affect the taste-testers’ ability to taste the food. It made it a little more difficult to specify the exact jam she tasted. For instance, when she was given the passion-mango jam spread she said it was simply a fruity, sweet jam. She did not say that it specifically tasted like mangos. However, when she found out what it was she said it tasted like mangos. From this we can determine that seeing your foods can inform your taste. When you see that a food is supposed to taste a certain way you may taste it simply out of the power of suggestion, rather than it actually tasting that way.

Activity 3:

How is the aroma involved in our sense of taste?

When I first ate the three types of potato chips I had no trouble differentiating between the different types. When I breathed in a BBQ chip while eating a plain potato chip I did not feel like I tasted BBQ. However, the aroma of the BBQ was quite overpowering. I felt like I was breathing in that aroma, but it did not really change the taste of the potato chip. In this case, aroma did not seem to be involved in my sense of taste. Although I believe them to be connected, it did not alter the taste of my food.

Activity 4: Desensitization

What does the taster observe?

The taster yelled out “Whoa that’s garlicy!” after tasting the garlic pita chips and hummus. She said that the garlic was very potent, but also delicious!
What do the non-tasters observe?
We were definitely able to smell the garlic not only on her breath but also just standing near the taster. It was quite a noticeable smell.

Can you still smell the garlic after everyone has some?

After we ate the garlic also we did not notice the smell on the original taster. We really did not seem to notice it anymore. We can conclude that by eating the garlic ourselves we had become desensitized the potent smell.

Activity 5: How does olfaction (smell) work?

Two of us smelled a variety of different smells while blindfolded. We both guessed the majority of the smells right or were at least in the ballpark of what the scents actually were. We also held two different solutions up to our noses at once: cloves and cinnamon. We noticed that the mixture was a very potent smell. The cinnamon, however, really seemed to overpower the cloves and smelled extremely strong. Both of the smells seemed to blend together into one strong scent that reminded me of Christmas!

Do any of these molecules have any similarity to the structure of the isoprene unit shown below?
I found three molecules that had this structure as a component of their overall structure:
- Vanillin, cinnamaldehyde, and benzaldehyde

Smelling the carvone solutions:
These were both extremely strong scents! The tube labeled (-) smelled like very strong spearmint. The (+) tube was also spearmint smelling but not as strong. The smells were extremely similar and made it difficult to differentiate between the two.

Why do the carvones have different smells?
These have different smells because they have slightly different molecular structures. Up above they are the same, however down below their hydrogens are facing different directions. Thus if they have different molecular structures, they are not going to give off the exact same smell.

Did you notice anything unusual? Are you satisfied with the explanation? Were the smells similar?

I noticed that both really smelled like spearmint and was perplexed as to why they could smell so similar, but not be exactly the same. We later found out that one was the scent Carroway and the other was Spearmint. However, they were so similar. This can only be explained by combinatorial chemistry.

How does combinatorial chemistry explain this?

This explains it because even though their structures may look similar our bodies can tell the difference between these two scents. These molecules may activate 5-10 receptors and many of them may be the same ones. However, down below, where their structures differ, that means they are going to activate some different sets of receptors. Thus, they are similar but not exactly the same in the scent that our brain perceives.

Other Questions:

Why are compounds with at phenyl ring more aromatic?

This is because of the alternating double bonds that these rings posses. This means that they have a lot of electrons freely moving about. This free moving gives rise to color and aroma.
Do you thing olfactory fatigue occurs more rapidly for good or bad aromas? Why is this good for you?
I think that olfactory fatigue occurs more rapidly for good smells. It seems to me that I smell bad smells for much longer than that of good smells. This could be a protective measure that our bodies take. This is because our bodies need to remember those bad odors as they may indicate toxic things to the body. So, the smell doesn’t phase out as quickly so our bodies are constantly reminded to stay away from the harmful substance.

What would it be like to lack the ability to smell? What would it change?

I think that it would make life rather drab and uninteresting. It would erase a lot of memories that familiar smells often bring. Smell is often a comfort measure that would also be lost. I would always feel like I was missing out on something or that things were not quite complete. It would change taste significantly. Without the ability to smell foods would taste drab and uninteresting. It could also change our ability to sense sour foods or harmful chemicals. We would not have that initial alert of smell to safeguard our bodies. Anosmia would be an awful condition to have that would affect more things than simply losing your sniffer!!!